UNIT 6/11 + OPTION D - Human Physiology

Question 1

Define nutrition

Answer 1

the process by which an organism acquires the matter and energy it requires from its environment

Question 2

State and define two types of nutrition

Answer 2

autotrophic nutrition - synthesis of organic molecules from simple inorganic substances

heterotrophic nutrition - obtaining organic molecules from other organisms

Question 3

List the types of heterotrophic nutrition

Answer 3

saprotrophic nutrition - feeding on dead organic matter

parasitic nutrition - feeding on the host’s tissues

holozoic nutrition - the ingestion of liquid or solid organic material from the bodies of other organisms, digestion in the alimentary canal or gut and then absorption and assimilation of it

Question 4

List the types of animals performing holozoic nutrition

Answer 4

herbivores - animals feeding directly and exclusively on plants

omnivores - animals eating both animal and plant material

carnivores - animals eating other animals

Question 5

List and define the five steps of holozoic nutrition

Answer 5

1. ingestion - food taken into mouth for processing in the gut
2. digestion - mechanical digestion by the action of teeth and the muscular walls of the gut & chemical digestion by enzymes, mainly in the stomach and intestine
3. absorption - soluble products of digestion absorbed from blood circulation system (lymphatic system if fat droplets)
4. assimilation - products of digestion absorbed from blood into body cells (liver and muscle cells) and used or stored
5. egestion - undigested food and dead cells from the lining of the gut, together with bacteria from the gut flora, expelled from the body as feces

Question 6

State the reason for digestion

Answer 6

food taken in consists of insoluble molecules that are too large to cross the gut wall themselves and enter the blood stream

by breaking down the food the body can obtain the subunits it needs to builds up its own macromolecules

Question 7

Describe the process of mechanical digestion

Answer 7

mastication (chewing) of food by teeth to break the ingested food into smaller pieces that are more readily digested through chemical digestion

peristalsis and segmentation

Question 8

Define peristalsis and segmentation

Answer 8

involuntary contraction of circular and longitudinal muscle layers of gastro intestinal tract mixes the food with enzymes and moves it along the gut

Question 9

Describe the process of chemical digestion

Answer 9

breakdown of complex molecules (fats, proteins, carbohydrates) into smaller molecules through water and digestive enzymes

Question 10

List the 3 most popular human digestive enzymes and what they digest, the products of this reaction and their optimum pH and where they are produced

Answer 10

• amylase - carbohydrates - ex. salivary amylase - substrate: starch -> product: maltose - source: salivary glands - pH: 7-7.8
• protease - proteins - ex. trypsin - substrate: polypeptides -> product: amino acids - source: duodenum glands - pH: 8
• lipase - lipids - ex. pancreatic lipase - substrate: triglycerides -> product: fatty acids & glycerol - source: pancreas - pH: 7.2-7.5

Question 11

Describe the process of carbohydrate digestion.

Answer 11

…

Question 12

Describe the process of lipid digestion.

Answer 12

lipids (fat and oils) (usually triglycerides) are emuslificated through bile salts into smaller droplets of triglycerides and then broken down by lipases into fatty acids and glycerol

Question 13

Why do triglycerides need emulsification

Answer 13

lipase is water-soluble but its substrates aren’t and so the enzymes can only attack the fat molecules at the surface of a mass of fat

emulsification increases the surface area of fat exposed to the action of pancreatic lipase and so increase the rate of lipid digestion

Question 14

Describe and distinguish between the two types of enzymes digesting proteins

Answer 14

endopeptidases (e.g. pepsin, trypsin) - hydrolyze bonds in polypeptide chains and so it breaks down large polypeptides into smaller ones increasing surface area for action of exopeptidases

exopeptidases (e.g. dipeptidase) - remove terminal amino acids which are then available for absorption

Question 15

Label the parts of digestive system.

Answer 15

• mouth
• salivary glands
• esophagus
• liver
• gallbladder
• stomach
• pancreas
• large intestine
• duodenum
• ileum
• rectum
• anus

Question 16

List the places with the processes where digestion happens in human body in the correct sequence

Answer 16

1. Mouth - mechanical digestion (chewing) and chemical digestion of starch (salivary amylase)
2. Esophagus - peristalsis
3. Stomach - mechanical digestion - muscular contractions (acid kills bacteria, pepsin digests proteins).
4. duodenum - bile from the liver and gall bladder neutralizes acid and emulsifies fats (pancreatic amylase and lipase digests carbohydrates and fats, trypsin digests polypeptides)
5. ileum - absorbs nutrients into the blood via the villi.
6. large intestine - water is reclaimed and returned to the blood leaving feces.
7. egestion - feces is forced out of the anus

Question 17

Label the structure of the stomach

Answer 17

• duodenum
• pyloric sphincter
• pyloric canal
• cardia
• esophagus
• muscularis externa ( longitudinal, circular and oblique layers)
• lumen
• body
• rugae of mucosa
• fundus
• serosa

Question 18

Describe and list the functions of the stomach

Answer 18

• killing bacteria and denaturing - proteins through hydrochloric acid (pH 2)
• protein digestion commencement - pepsin
• mechanical digestion - muscular actions
• food storage in the lumen
• control of entry of food and exit of chyme with muscular sphincters
• mixing enzymes with food through muscular wall contractions

Question 19

How does the stomach trigger the release of enzymes

Answer 19

stretch receptors in the muscular wall

Question 20

List the components and their function of the gastric juice

Answer 20

hydrochloric acid - creates an acid environment of pH 1.5-2 which is optimum for protein digestion by the protease enzymes, activates inactive enzymes, kills many bacteria present in the food
protease enzymes - secreted in inactive state, begin the digestion of proteins

Question 21

State the function of gastric glands

Answer 21

present in the wall of the stomach and secrete the components of gastric juice

Question 22

Define goblet cells

Answer 22

cells present in the stomach lining and secrete mucus

Question 23

State the function of mucus

Answer 23

bathing of the interior lining of the stomach, forming an effective barrier to both hydrochloric acid and the protease, preventing autolysis of the stomach wall

Question 24

Define chyme

Answer 24

semi-liquid resulting from the squeezing of the food and mixing it with the gastric juice

Question 25

State the two main functions of the small intestine

Answer 25

digestion of carbohydrates, lipids and proteins the absorption of useful products of digestion

Question 26

Describe the processes occurring in the small intestine

Answer 26

1. chyme enters the duodenum bile from the gallbladder and liver is emptied into the duodenum, neutralizing the acid and emulsifying fats 2. pancreatic enzymes are released and further released into the jejunum 4. the ileum conducts the absorption of digested food molecules through villi 5. a wave of muscle contractions (peristalsis) keeps the mixture of digested and undigested food moving through the intestine

Question 27

State the function of the bile and where it is produced and stored

Answer 27

produced: liver cells stored: gall bladder is strongly alkaline and neutralizes the acidity of the chyme also emulsifies lipids

Question 28

State what forms pancreas

Answer 28

acini - large number of lobules with central lumen (pancreatic capillary)

Question 29

Define absorption in the small intestine

Answer 29

uptake into the body (blood circulation or lacteals) of the useful products of digestion, from the gut lumen

Question 30

State the adaptation of villi to its function

Answer 30

single layer of epithelial cells - short diffusion path rich blood supply - maintains a concentration gradient down which nutrients can diffuse across the membranes lymph vessels (lacteals) close to the surface - allows lipids to be easily absorbed mucus from goblet cells in epithelium - lubricates the movement of digested food among the villi and protects plasma membrane of epithelial cells epithelium cells packed with mitochondria - source of ATP for active uptake across the plasma membrane

Question 31

Describe the process of absorption of fats

Answer 31

1. triglycerides in the lumen are exposed to enzymatic hydrolysis by lipase breaking down the triglycerides into fatty acids and monoglycerides. 2. those products diffuse into epithelial cells, the monoglycerides and fatty acids are reformed into triglycerides (some of them) 3. triglycerides are incorporated into water-soluble globules - chylomicrons. 4. chylomicrons leave epithelial cells by exocytosis and enter lacteals where they are carried away by the lymph and later pass into large veins

Question 32

Describe the process and state the name of absorption mechanism of glucose through the epithelium

Answer 32

in the kidney or intestine (only) the sodium-glucose symporter binds both glucose and Na+ (the coupling with Na+ relies on it and allows to get glucose out of the lumen even at very low concentrations, and the gradient of Na+ is maintained constantly because of the sodium potassium pump) and because of that it is passive facilitated diffusion

Question 33

Describe the process or amino acid and short chain polypeptides uptake into the bloodstream

Answer 33

1. proteins and their fragments are digested to amino acids by pancreatic proteases (trypsin, chymotrypsin and carboxypeptidase) along with the brush border enzymes of mucosal cells (carboxypeptidase, aminopeptidase and dipeptidase) 2. the amino acids are absorbed by primary active transport to the absorptive cells and moved toward its opposite side 3. the amino acids leave the villus epithelial cell by facilitated diffusion and enter the capillary via intercellular clefts

Question 34

List the pancreatic proteases

Answer 34

- trypsin - chymotrypsin - carboxypeptidase

Question 35

Define assimilation

Answer 35

uptake of nutrients into cells and tissues

Question 36

Describe the steps of assimilation

Answer 36

absorbed nutrients are transported from the intestine into the villi: 1. sugars into capillary network and from them into the liver. 2. amino acids too are transported into the capillary network and transported into the liver. 3. the lipids are absorbed as fatty acids and glycerol and are largely absorbed into the lacteal vessels then carried by the lymphatic system to blood

Question 37

State the role of the large intestine

Answer 37

- walt and mineral salts are absorbed - undigested and undigestible food (e.g. cellulose), bacteria, dead cells, mucus, bile pigments form the feces which is stored and consolidated in the rectum and then passed out periodically by the anus controlled by anal sphincters

Question 38

List the general functions of the liver

Answer 38

- secretes bile - important in mechanical digestion of fats - helps maintain homeostasis by regulating nutrient concentration in the blood - converts excess glucose to glycogen and stores it - converts excess amino acids to fatty acids and urea - stores iron and certain vitamins - detoxifies alcohol and other drugs and poisons

Question 39

Label the tissue map of a section through the stomach wall

Answer 39

- serosa - longitudinal muscle - circular muscle - oblique muscle - submucosa - glandular epithelium - connective tissue with gastric glands - muscle

Question 40

Label the section of the villus

Answer 40

- lacteal - capillary network - epithelial cell - arteriole - lymphatic vessel - venule

Question 41

List the digestive exocrine glands present in human digestive system

Answer 41

- salivary glands - pyloric glands (stomach) - exocrine pancreas - goblet cells (small intestine)

Question 42

List the contents of saliva with their corresponding functions

Answer 42

- amylase - starch digestion - lingual lipase - breaks triglycerides into fatty acids - water and electrolytes - moistens and lubricates - mucus - lubricates food bolus - antibacterial compounds and bacteria

Question 43

List the contents of the gastric juice with their functions

Answer 43

contents: - hydrochloric acid - begins protein digestion and activates pepsin - mucus - protects the stomach lining - enzymes - pepsin and rennin - digest

Question 44

State where is the gastric juice produced by and when

Answer 44

where: by the parietal cells in the stomach wall when: when polypeptides are detected

Question 45

List the cell types present in the stomach and the substance secreted by them and their function

Answer 45

- goblet cells - mucus - protects stomach lining - parietal cells - gastric acid - chief cells - pepsinogen - D cells - somatostatin - inhibits acid secretion - G cells - gastrin - stimulates acid secretion

Question 46

List the contents of the pancreatic juice and its pH

Answer 46

basic pH because the bicarbonate ions neutralize acidic gastric products contains many different enzymes: pancreatic lipase and amylase, endopeptidases (trypsin and chymotrypsin) and exopeptidases (carboxypeptidase and elastase)

Question 47

Determine why the enzymes are excreted in a different form (name it)

Answer 47

secretion as active enzymes would cause damage to the exocrine cells - autodigestion thus they are excreted as inactive precursors which are harmless and become activated under the right conditions

Question 48

State the name and describe how the enzyme acidifying the stomach works

Answer 48

hydrogen potassium (H+/K+) ATPase exchanges potassium from the intestinal lumen with cytoplasmic hydronium and thus creates acidic environment in the stomach contents allowing for pepsin activation

Question 49

State the purpose of using PPIs and their mechanism of functioning

Answer 49

Proton Pump Inhibitors irreversibly bind to the proton pumps and prevent H+ ion secretion which is sometimes increased by certain medications or diseases they raise the pH of the stomach consequently and thus prevent gastric discomfort (acid reflux f. e.) caused by high acidity

Question 50

Discuss the roles of gastric acid and Heliobacter pylori in the development of stomach cancers

Answer 50

..

Question 51

State the stages of control of gastric juice secretion with the nerves and hormones involved

Answer 51

Cephalic phase - reflex response to visual, smell or thought stimulus via the vagus nerve causing gastric juices to be released. Gastric phase - in response to mechano- (stretch) and chemo- (protein) receptor stimuli the medulla oblongata sends a signal to the gastric pit to start secreting digestive juices. Intestinal phase - reduces secretions: low pH or arrival of lipids in the small intestines is detected by the medulla oblongata and thus secretes a hormone stopping the production of gastric juices and moves food to the small intestine.

Question 52

Describe how the acidic chyme from the stomach is neutralized when it moves to small intestine

Answer 52

duodenum responds to amino acids and fatty acids in the chyme by releasing the digestive hormones cholecystokinin and secretin CKK stimulates the release of digestive enzymes from the pancreas and of bile from the gallbladder secretin stimulates the pancreas to release bicarbonate (HCO3-) which neutralizes chyme

Question 53

Describe the nervous mechanism triggered by food

Answer 53

the sight and smell of food triggers an immediate response by which gastric juice is secreted by the stomach pre-ingestion and when food enters the stomach it causes distension which is recognized by the stretch receptors in the stomach lining which send signals to the medulla oblongata in the brain which triggers the release of digestive hormones sustaining gastric stimulation

Question 54

Describe and define the mechanism of action of cholera toxin

Answer 54

Vibrio cholerae is a bacterial pathogen infecting the intestines and causing acute diarrhea and dehydration - cholera - it can kill within hours unless treated with oral rehydration therapies 1. V. cholerae releases a toxin that binds to ganglioside receptors on the surface of intestinal epithelium cells which is then internalized by endocytosis and triggers the production of cyclic AMP within the cell 2. cAMP activates specific ion channels within the cell membrane, causing an efflux of ions from the cell and thus the build up of ions in the intestinal lumen which draws water from the cells and tissues via osmosis (causing diarrhea) 3. water being removed from the body tissues and thus causes severe dehydration

Question 55

State the role of tight junctions in the epithelial cells of the small intestine

Answer 55

prevents the movement of molecules between neighboring cells

Question 56

State the role of fiber in the digestive process

Answer 56

helps move food along the alimentary canal especially cellulose fiber

Question 57

List the functions of the large intestine

Answer 57

- recovery of water and electrolytes from ingesta - formation and storage of feces - as ingesta is moved through the large intestine it is dehydrated, mixed with bacteria and mucus and formed into feces - microbial fermentation - microbes in feces produce enzymes capable of digesting many molecules that to vertebrates are indigestible (cellulose for example)

Question 58

List materials not absorbed and thus egested by feces

Answer 58

- lignin and cellulose from plant foods - dead cells from the intestine - bacteria - bile pigments

Question 59

Describe the unique blood supply of the liver

Answer 59

- receives oxygenated blood via the hepatic artery which is used to sustain liver cells - receives nutrient rich blood from the gut via the portal vein - deoxygenated blood is transported form the liver via the hepatic vein

Question 60

List the functions of the liver

Answer 60

many others, its the most complex organ in the body - secretes bile - important for mechanical digestion of fats (emulsification) - helps maintain homeostasis by regulating nutrient content in the blood - converts excess glucose to glycogen and stores it - synthetizes glucose from non-carbohydrate sources (gluconeogenesis) - converts excess amino acids to fatty acids and urea - manufactures heparin and plasma proteins f. e. albumin stores iron and certain vitamins (A, D, E, K, B12) - detoxifies alcohol and other drugs and poisons that enter the body - synthetizes cholesterol from acetyl CoA

Question 61

State the name of the structural and functional units of liver and their cell composition and structure

Answer 61

liver lobules - hexagonal in structure consists of plates of hepatocytes radiating outwards from the central vein at each six corners of a lobules there is the portal triad (portal tract region)

Question 62

List the structures and their functions that the portal triad consists of

Answer 62

- branch of hepatic artery - supplies oxygen-rich arterial blood to the liver - hepatic portal vein - carries venous blood laden with nutrients from the digestive viscera - bile duct

Question 63

Define a sinusoid

Answer 63

small blood vessel found in the liver perfoming a similar function to capillaries - material exchange

Question 64

State and describe the adaptation of sinusoid

Answer 64

increased permeability allowing larger molecules for example: plasma protein to enter and leave the bloodstream structurally: surrounding diaphragm (basement membrane) is incomplete or discontinuous in sinusoids (but not in capillaries ) endothelial layer contains large intercellular gaps and fewer tight junctions

Question 65

State the main difference between the sinusoids in the liver and capillaries in most organs

Answer 65

in capillaries because they do not have walls separating blood from the liver cells the two are in direct contact

Question 66

State how the blood is transported in hepatocytes from the hepatic portal vein

Answer 66

from hepatic portal vein and the hepatic artery percolates from the triad regions through these sinusoids and empties in the central vein from where it eventually enters the hepatic veins (draining the liver) and empties into the inferior vena cava

Question 67

List the adaptations of liver sinusoids to detoxify the blood

Answer 67

- hepatocytes in general - Kupffer cells - engulfing microbes and breaking down RBC - Stellate cells - forming a scar tissue in response to liver damage

Question 68

State the names of two circulating hormones regulating glucose related metabolic activities in the liver

Answer 68

- insulin - glucagon

Question 69

Define gluconeogenesis

Answer 69

synthesis of glucose from other compounds

Question 70

Describe the process of glucose regulation by negative feedback

Question 71

List and state the function of the nutrients stored in the hepatocytes

Answer 71

- calciferol (vit D) - helps uptake of calcium - retinol (vit A, from carotene) - used to make other vitamins - iron - used to make hemoglobin

Question 72

Describe how the liver metabolizes the stored fats

Answer 72

they are broken down into smaller compounds and combined with coenzyme A to form molecules (through B-oxidation) of acetyl coenzyme A which will enter the citric acid cycle

Question 73

List the contents of bile

Answer 73

- hydrogen carbonate ions - bile pigment - bile salts - cholesterol

Question 74

Describe how bile is released

Answer 74

1. produced by hepatocytes and secreted into narrow bile canaliculi. 2. it is carried in larger ducts to the gall bladder where it is stored and the water is re-absorbed. 3. bile is released into the duodenum via the bile duct.

Question 75

State the function of bile

Answer 75

- elimination of cholesterol because it makes it soluble by bile acids and lipids - emulsification of lipid aggregates through the bile acids - solubilization and transport of lipids in an aqueous environment - bile acids are lipid carriers and so able to solubilize many lipids forming micelles - transport and absorption of fat-soluble vitamins

Question 76

State how gallstones form

Answer 76

result from processes that allow cholesterol to precipitate from solution in bile

Question 77

Describe the breakdown of red blood cells

Answer 77

1. phagocytosis by Kupffer cells in the liver. 2. hemoglobin is converted to a yellow pigment - bilirubin - and transferred to the bile. 3. iron is transferred to the blood through binding to transferrin protein - stored as ferritin or incorporated into the heme molecule. 4. protein is broken down to amino acids which are released into the blood. 5. bilirubin is converted to a yellow pigment in the intestine which gives feces the characteristic yellow colour.

Question 78

Define Jaundice

Answer 78

term used to describe a yellowish tinge to the skin and sclerae and body fluids that is caused by hyperbilirubinemia

Question 79

Define hyperbilirubinemia

Answer 79

excess of bilirubin in the blood

Question 80

Define bilirubin

Answer 80

waste product remaining in the bloodstream after the iron is removed from the hemoglobin during the degradation of erythrocytes

Question 81

List the causes of jaundice

Answer 81

- acute inflammation of the liver - impairs the ability to conjugate and secrete bilirubin resulting in its buildup. - inflammation of the bile duct - prevents the secretion of bile and removal of bilirubin. - obstruction of the bile duct - prevents the liver from disposing of bilirubin. - hemolytic anemia - large quantities of erythrocytes are broken down and thus the production of bilirubin increases.

Question 82

Label the structures of the circulation system.

Answer 82

- head and upper limb capillaries - superior vena cava - inferior vena cava - aorta - hepatic artery - hepatic portal vein - splenic artery - mesenteric artery - renal afferent arterioles - common iliac artery - common iliac vein - trunk capillaries - lower limb capillaries - renal efferent arterioles

Question 83

Label the diagram of the upper abdomen

Answer 83

- inferior vena cava - right lobe of liver - right hepatic duct - common bile duct - gallbladder - stomach - pancreas - hepatic portal vein -duodenum

Question 84

Label the diagram of a hepatocyte

Answer 84

- interlobular veins - central vein - bile canaliculi - bile duct - fenestrated lining - portal venule - portal arteriole - stellate macrophages in sinusoid walls - portal vein - sinusoids - plates of hepatocytes

Question 85

Label the diagram of sinusoid and hepatocyte

Answer 85

- hepatic artery - hepatic vein - bile duct - sinusoid blood-filled channel - phagocytic cells

Question 86

Differentiate between the needs of small and larger organisms for a transport system

Answer 86

small - simple diffusion across body surface or active transport larger - require a circulatory system to transport materials because diffusion is too inefficient and slow to supply all the cells of the body

Question 93

State the reason for the name double circulation in mammalian circulation

Answer 93

blood passes twice through the heart in every single circulation of the body

Question 93

List the components of mammalian blood with their abbreviated functions

Answer 93

- water - solvent - ions (blood electrolytes) - osmotic balance, pH buffering, regulation of membrane permeability - plasma proteins - albumin - pH Buffering and osmotic balance, immunoglobulins - defense, fibrinogen - clotting etc. - substances transported by blood such as nutrients, respiratory gases, hormones or waste products of metabolism - leukocytes - defense and immunity - platelets - blood clotting - erythrocytes - transport of O2 and some CO2

Question 93

State two advantages of mammalian circulation

Answer 93

simultaneous high-pressure delivery of oxygenated blood to all regions of the body oxygenated blood reaches the respiring tissues, undiluted by deoxygenated blood

Question 93

Define blood

Answer 93

specialized tissue consisting of liquid medium - plasma - and blood cells

Question 93

Distinguish the types of leukocytes

Answer 93

phagocytes - granulocytes (basophil, neutrophil, eosinophil) - monocytes -> macrophages lymphocytes (T or B)

Question 94

State the shape of erythrocytes

Answer 94

biconcave

Question 95

List the components of hemoglobin

Answer 95

- 2x beta globin chain - 2x alpha globin chain - iron-containing heme group

Question 96

List the functions of blood plasma

Answer 96

transport of: - nutrients from gut or liver to all cells - excretory products (for example - urea) from the liver to the kidneys - hormones from the endocrine glands to all tissues and organs - dissolved proteins - osmotic concentration regulation - antibodies - heat distribution to all tissues

Question 97

List the functions of blood erythrocytes

Answer 97

transport of: - oxygen from lungs to respiring tissues - carbon dioxide from respiring cells to lungs

Question 98

List the function of blood lymphocytes

Answer 98

forming antibodies

Question 99

List the functions of blood phagocytes

Answer 99

ingestion of bacteria or other cell fragments

Question 100

List the functions of blood platelets

Answer 100

play a part in the blood clotting mechanism

Question 101

List and briefly define the types of vessels in the mammalian circulation system

Answer 101

- arteries - carry blood away from the heart - veins - carry blood back to the heart - capillaries - fine networks of tiny tubes linking arteries and veins

Question 102

List the structural differences between arteries, veins and capillaries

Answer 102

CAPILLARY - site of exchange between blood and body tissues - outer layer (collagen fibres) = absent - middle layer (elastic fibres and involuntary muscle fibres) = absent - inner layer or endothelium (pavement epithelium) = present - valves = absent ARTERY - carries blood under high pressure away from the heart - outer layer (collagen fibres) = present - middle layer (elastic fibres and involuntary muscle fibres) = thick layer - inner layer or endothelium (pavement epithelium) = present - valves = absent VEIN - carries blood under low pressure back to the heart - outer layer (collagen fibres) = present - middle layer (elastic fibres and involuntary muscle fibres) = thin layer - inner layer or endothelium (pavement epithelium) = present - valves = present

Question 103

State the function and list the adaptations of arteries

Answer 103

to convey blood at high pressure from the heart ventricles to the tissues of the body and lungs - narrow lumen (relatively to the wall thickness)- maintaining high blood pressure - thick wall (outer collagen layer) - prevention of rupturing under the high pressure - inner layer of muscle and elastic fibers - help maintain pulse flow (can contract and stretch)

Question 104

State the function and list the adaptations of capillaries

Answer 104

to exchange materials between the cells in tissues and blood travelling at low pressure - splitting of arteries -> arterioles -> capillaries - decreasing arterial pressure and increasing the total vessel volume, ensuring thorough blood supply to all cells - capillaries pool into venules and then larger veins after the material exchange occurred - very small diameter - passage of only one single blood cell at the time - wall made of a single cell layer - minimizing diffusion distance for permeable materials - basement membrane - permeable to necessary materials - contain pores - aid the transport of materials between the tissue fluid and blood

Question 105

List the types of capillary wall possible and its location in the body

Answer 105

- continuous (endothelial cells held by tight junctions to limit permeability) - fenestrated (with pores) - in tissues specialized for absorption (e.g. intestines, kidneys) - sinusoidal (have open spaces between cells) - permeable to large molecules and cells - e. g. liver

Question 106

Compare the three blood vessel types under the following categories: function, pressure, lumen diameter, wall thickness, wall layers, muscle & elastic fibers, valves

Answer 106

ARTERY function = send blood from heart Pressure = high Lumen diameter = narrow Wall thickness = thick Wall layers = 3 (tunica adventitia, media, intima) Muscle and elastic fibres = large amounts Valves = no VEIN function = send blood to heart Pressure = low Lumen diameter = wide Wall thickness = thin Wall layers = 3 (tunica adventitia, media, intima) Muscle and elastic fibres = small amounts Valves = yes CAPILLARY function = material exchange with tissues Pressure = low Lumen diameter = very narrow (1 cell wide) Wall thickness = very thin Wall layers = 1 (tunica intima) Muscle and elastic fibres = none Valves = no

Question 107

State to common placement of valves in veins and their function there

Answer 107

veins of the limbs prevents reversed blood flow caused by the pressure from movements of the surrounding tissues including the contractions of the muscles, which compress the vein valve is closed by blood pressure from in front and opened by that from behind

Question 108

State and briefly distinguish the two types of circulation present in double circulation

Answer 108

pulmonary circulation - to and from lungs systemic circulation - to and from all other organs including the wall of the heart

Question 109

Briefly describe the process of pulmonary circulation

Answer 109

right side of the heart (right ventricle) pumps deoxygenated blood through pulmonary artery to the lungs where it is oxygenated then the blood flows in pulmonary veins to the left side of the heart (left atrium)

Question 110

Briefly describe the process of systemic circulation

Answer 110

organs are supplied with blood through and artery branching from the main aorta. within organs the artery branches into numerous arterioles and the smallest arterioles supply the capillary networks which allow the efficient exchange of nutrients, oxygen and wastes between the blood and tissues. capillaries drain into venules and venules join to form veins which consequently join the vena cava carrying blood back to the right atrium.

Question 111

State the branching sequence in the circulation

Answer 111

aorta -> artery -> arteriole -> capillary -> venule -> vein -> vena cava

Question 112

State the names of the blood vessels supplying the liver and what they carry

Answer 112

- hepatic artery - hepatic portal vein - products of digestion after they have been absorbed into the capillaries of the villi

Question 113

State the location of the human heart

Answer 113

in the thorax between the lungs and beneath the sternum (breast bone)

Question 114

State the general structure of the human heart

Answer 114

- surrounded by the pericardium - divided into four chambers (two upper atria and two lower ventricles) - muscular wall of the left ventricle is much thicker than the right ventricle though volumes of both ventricles are identical

Question 115

Define pericardium

Answer 115

strong, non-elastic sac anchoring the heart within the thorax

Question 116

State the function and types of valves present in the human heart, distinguish them

Answer 116

prevent the backflow of blood, maintaining the direction of flow through the heart - atrio-ventricular valves - larger valves preventing backflow from ventricles to atria while the ventricles contract, their edges are supported by tendons - semilunar valves - separation of the ventricles from the pulmonary artery (right) and aorta (left), cut out the backflow from aorta and pulmonary artery into the ventricles as the ventricles relax between heartbeats

Question 117

State the reason for the atrio-ventricular valves to be supported by tendons

Answer 117

prevention of the folding back of the valves due to huge pressure developing with each heart beat

Question 118

State an alternative name for the heart muscle

Answer 118

myocardium

Question 119

Define coronary circulation

Answer 119

circulation of blood in the blood vessels of the heart muscle

Question 120

State and distinguish between the types of vessels present in the coronary circulation

Answer 120

- coronary arteries - deliver oxygen-rich blood o the myocardium - cardiac veins - remove the deoxygenated blood from the cardiac muscle - coronary sinus - returns the collected deoxygenated blood from the cardiac veins to the right atrium

Question 121

List the general steps of the cardiac cycle

Answer 121

1. atrium muscles contract pushing blood past the bicuspid valve into the ventricles. 2. atrium muscles relax 3. ventricle muscles contract causing the blood pressure to close the bicuspid valve and open the semilunar valve forcing blood into the aorta. 4. ventricle and atrium muscles relax while the pressure of blood in the aorta causes the semilunar valves to shut. 5. blood flows into the atrium and opens the bicuspid valve as it starts to flow into the ventricle.

Question 122

Define the cardiac cycle and its two phases

Answer 122

one complete sequence of pumping the blood and filling the chambers systole - contraction phase of the cycle diastole - relaxation phase

Question 123

List and describe the cardiac cycle in three steps

Answer 123

1. atrial and ventricular diastole (0.4 s) - relaxation phase where blood returning from large veins flows into the atria and then into the ventricles through the AV valves. 2. atrial systole and ventricular diastole (0.1 s) - atrial contraction forcing all blood remaining in the atria into the ventricles. 3. ventricular systole and atrial diastole (0.3 s) - ventricular contraction pumps blood into the large arteries through the semilunar valves.

Question 124

State the duration of a complete cardiac cycle in an adult human and the bpm

Answer 124

72 beats per minute 0.8 s of the cycle

Question 125

Describe in detail the process of atrio-ventricular and semilunar valve functioning

Answer 125

1. blood returning to the heart fills atria pressing against the AV vales which pressure caused them to open. 2. as the ventricles fill up the AV valve flaps hang limply into ventricles. 3. atria contract forcing additional blood into the ventricle. 4. ventricles contract forcing blood against the AV valve cusps and thus to close the AV valves. 5. papillary muscles contract and chordae tendinea tighten preventing valve flaps from everting into atria. 6. as the ventricles contract and intraventricular pressure rises the blood is pushed up against the semilunar valves forcing them to open. 7. as the ventricles relax blood flows back from arteries filling the cusps of semilunar valves and forcing them to close.

Question 126

Compare the diastole, atrial systole and ventricular systole phases of the cardiac cycle taking into account: the state of atria and ventricles, blood positioning, AV and SL valves state

Answer 126

DIASTOLE - atria and ventricles relaxed - blood flows into heart from veins - AV valves open - SL valves closed (heart sound 2) ATRIAL SYSTOLE - atria contract - ventricles relaxed - blood pushed into atria - AV valves open - SL valves closed VENTRICULAR SYSTOLE - atria relaxed - ventricles contract - blood pushed into arteries - AV valves closed (heart sound 1) - SL valves open

Question 127

State and define the characteristic of the heart beat

Answer 127

myogenic in origin origin of each beat is within the heart itself

Question 128

State the component of the intrinsic cardiac conduction system

Answer 128

noncontractile cardiac cells specialized to initiate and distribute impulses throughout the heart so that it depolarizes and contracts in an orderly, sequential manner

Question 129

State and describe the sequence of electrical excitation in the human heart

Answer 129

1. sinoatrial node (pacemaker) generates impulses. 2. the impulses pause (0.1 s) at the atrioventricular node. 3. the atrioventricular bundle connects the atria to the ventricles. 4. the bundle branches conduct the impulses through the interventricular septum. 5. subendocardial conducting network (Purkinje fibers) depolarizes the contractile cells of both ventricles.

Question 130

Define an ECG

Answer 130

electrocardiogram graphic record of heart activity

Question 131

State the function of the delay of the electrical impulse before spreading to the heart apex.

Answer 131

allows the atria to empty completely before the ventricles contract

Question 132

Relate the stages of the electrical excitation of the heart with the waves on the electrocardiogram.

Answer 132

1. atrial depolarization initiated by the SA node - P wave. 2. impulse delayed at the AV node - space between finish of the P wave and Q dip. 3. ventricular depolarization being at apex along with atrial repolarization - QRS complex. 4. ventricular depolarization - space between QRS and T wave. 5.ventricular repolarization begins - T wave 6.ventricular repolarization is complete - end.

Question 133

Give examples of heart conditions

Answer 133

- tachycardia - elevated resting heart rate >120 bpm - bradycardia - depressed resting heart rate <40 bpm - arrhythmias - irregular heartbeats (very common in young people) - fibrillations - unsynchronized contractions of either atria or ventricles leading to dangerously spasmodic heart activity

Question 134

State the location and distinguish between the two types of the human heart cardiovascular center

Answer 134

located in the medulla oblongata cardioacceleratory center - projects to sympathetic neurons via the spinal cord which in turn synapse with neurons in the sympathetic trunk, from there the fibers run to the heart where they innervate the SA and AV nodes, heart muscle and coronary arteries. cardioinhibitory center - sends impulses to the parasympathetic dorsal vagus nucleus in the medulla oblongata which in turn sends inhibitory impulses to the heart via branches of the vagus nerves

Question 135

List the parts of the nerve signaling controlling the human heart activity

Answer 135

- medulla oblongata involuntarily controls the pacemaker - sympathetic nerve releasing noradrenaline (norepinephrine) increases the heart rate - parasympathetic nerve (vagus nerve) releases the neurotransmitter acetylcholine to decrease heart rate

Question 136

List the parts of the hormone signaling controlling the human heart activity

Answer 136

release of the adrenaline hormone (epinephrine) from the adrenal glands (above the kidneys) and thus increasing heart rate by activating the same chemical pathways as the neurotransmitter noradrenaline can happen in order to prepare for vigorous physical activity

Question 137

Distinguish between the short-term and long-term response to stress of the adrenal glands

Answer 137

..

Question 138

List the short-term (epinephrine and norepinephrine) and long-term (mineralocorticoids, glucocorticoids) effects of stress

Answer 138

epinephrine & norepinephrine: - glycogen broken down to glucose, increased blood glucose level - increased blood pressure - increased breathing rate - increased metabolic rate - change in blood flow patterns -> increased alertness and decreased digestive, excretory and reproductive system activity mineralocorticoids: - retention of sodium ions and water by kidneys - increased blood volume and pressure glucocorticoids: - proteins and fats broken down and converted to glucose, increased blood glucose - partial suppression of the immune system

Question 139

Describe the disease of atherosclerosis: its cause and effects

Answer 139

degenerative disease where areas of the artery wall become damaged the macrophages will release growth factors encouraging the growth of fibrous tissue while the cholesterol builds up in the damaged areas eventually forming plaques and the arterial wall loses elasticity plaques restrict blood flow and as the plaque ruptures blood clotting is triggered (coronary thrombosis)

Question 140

State alternative name and define a heart attack

Answer 140

myocardial infraction the coronary arteries become completely blocked leading to death of the coronary muscle tissue as a result of a lack of blood and oxygen

Question 141

List the risk factors in coronary heart disease

Answer 141

- genetic predisposition for high cholesterol levels/blood pressure - age - sex - males at greater risk - smoking - constricts blood vessels, increases blood pressure, decreases oxygenation of the heart muscle, increased clotting though increased fibrogen and platelets - diet - increased fat/cholesterol/LDL in blood leads to plaque formation in arteries - exercise and obesity - weakened circulation, increase in blood pressure, formation of plaques - stress - increased cortisol causing increased atherosclerosis

Question 142

State the types of leukocytes

Answer 142

GRANULOCYTES - neutrophil: multilobed nucleus, pale red and blue cytoplasmic granules. - eosinophil: bilobed nucleus, red cytoplasmic granules. - basophil: bilobed nucleus, purplish-black, cytoplasmic granules. AGRANULOCYTES - lymphocytes: large spherical nucleus, thin rim of pale blue cytoplasm - monocyte: kidney-shaped nucleus, abundant pale blue cytoplasm.

Question 143

Label the structures of the blood vessels

Answer 143

Capillary - endothelium Artery + vein - outer layer - middle layer - the hollow centre of a tube is the lumen - endothelium

Question 144

Label the structure of the heart.

Answer 144

- superior vena cava - inferior vena cava - right pulmonary trunk - right atrium - right pulmonary veins - tricuspid valve - right ventricle - aorta - left pulmonary artery - left atrium - left pulmonary veins - mitral (bicuspid) valve - aortic valve - pulmonary valve - left ventricle - papillary muscle - interventricular septum - epicardium - myocardium - endocardium

Question 145

Label the cardiac conduction system

Answer 145

- Sino-atrial node (SA) - AV bundle - atrio-ventricular node (AV) - Purkinje fibres - right and left bundle branches

Question 146

List the ECG cardiac rhythms

Answer 146

- normal sinus rhythm - arrhythmia - bradycardia - tachycardia - atrial fibrillation - ventricular fibrillation

Question 147

State the reason for heart sounds

Answer 147

1st - closing of the AV valves at ventricular contraction 2nd - closing of SL valves after systole (pressure in the ventricle is lower than in aorta - backflow of blood closes valve)

Question 148

Describe the meaning of A, B, #, *, +, x, y, z

Answer 148

A - atrial contraction B - ventricular contraction # - increase in atrial pressure due to atrial contraction * - increase in ventricular pressure as ventricle contracts forcing blood into the aorta and increasing aortic pressure + - increase in atrial pressure due to the inflow of blood returning to heart from the veins following systole ventricular volume: x - increases as atrial contraction forces blood into the ventricle y - decreases as ventricular contraction forces blood into the aorta z - increases as blood returns to the heart following systole

Question 149

Define ventilation

Answer 149

movement of air into and out of the lungs in two stages: inspiration and expiration, controlled by a movement of the diaphragm and ribcage

Question 150

Define gas exchange

Answer 150

diffusion of oxygen and carbon dioxide to and from the blood at the alveoli and the respiring tissues

Question 151

List the factors affecting diffusion

Answer 151

- size of the surface area available for gaseous exchange (respiratory surface) - concentration gradient - length of the diffusion path

Question 152

State the factor necessary for the gas exchange to be efficient and what is it achieved by

Answer 152

high concentration gradients maintained in the alveoli breathing in increases concentration gradients of oxygen between the alveoli and blood so that it diffuses into the blood while breathing out removes CO2 increasing the concentration gradients of CO2 between the blood and the alveolus so that CO2 will diffuse out

Question 153

State the two factors that improve the condition for diffusion in mammals

Answer 153

a blood circulation system which transports oxygen into the body cells a respiratory pigment (hemoglobin) which increases the oxygen carrying ability of the blood

Question 154

Define human thorax

Answer 154

airtight chamber formed by the rib-cage and its muscles (intercostal muscles) and the diaphragm

Question 155

Define a diaphragm

Answer 155

a sheet of muscles attached to the body wall separating thorax from abdomen

Question 156

State the name and function for the membrane lining up the internal surface of the thorax

Answer 156

pleural membrane secretes and maintains pleural fluid

Question 157

Define pleural fluid

Answer 157

lubricating liquid that protects the lungs from friction during breathing movements

Question 158

State the function of glottis and epiglottis

Answer 158

prevention of the entry of food into the trachea

Question 159

State the function of incomplete rings of cartilage in the trachea

Answer 159

prevention of the collapse under pressure from the large boles of food passing down the esophagus

Question 160

State the adaptation of bronchi and larger bronchioles to the pressure of a powerful inspiration of air

Answer 160

smooth muscles lining the walls and rings or tiny plates of cartilage

Question 161

State the reason why lungs have a very large surface area

Answer 161

to increase the overall rate of gas exchange

Question 162

State the structure of a bronchiole

Answer 162

a cluster of alveoli with a capillary system wrapped around the cluster and connected to a branch of the pulmonary artery and drained by a branch of the pulmonary veins

Question 163

Define type I pneumocytes

Answer 163

extremely thin alveolar cells adapted to carry out gas exchange

Question 164

State the adaptation of the alveolar cell wall to gas exchange

Answer 164

wall of alveoli consist of a single layer of flattened cells (pavement epithelium) with extremely narrow capillaries so that the distance over which oxygen and carbon dioxide has to diffuse is very small

Question 165

Define the function of type II pneumocyte

Answer 165

secrete a solution containing surfactant reducing the surface tension and preventing the water from causing the sides of alveoli to adhere when air is exhaled from the lungs which helps prevent the collapse of the lung

Question 166

State the structural adaptations of alveoli to their role

Answer 166

- very thin epithelial layer - minimize diffusion distance for respiratory gases - rich capillary network - increased capacity for gas exchange with the blood - spherical in shape - maximize the available surface area for gas exchange - layer of fluid internally - facilitation of the diffusion of the dissolved gases into the bloodstream

Question 167

State the mechanism of gas exchange by diffusion in the alveoli

Answer 167

oxygen dissolved in the surface film of water, diffuses across into the blood plasma and into red cells where it combines with haemoglobin to form oxyhaemoglobin simultaneously carbon dioxide diffuses from blood into the alveoli

Question 168

Describe the principle behind negative pressure breathing and its effect on human respiration

Answer 168

gases will move from a region of high pressure to a region of lower pressure and thus when the pressure in the chest is less than the atmospheric pressure the air will move into the lungs - inspiration when the pressure in the chest is greater than the atmospheric pressure, air will move out of the lungs - expiration

Question 169

List the human respiratory muscles

Answer 169

muscles of inspiration core muscles: - external intercostals (contracts to elevate ribs) - diaphragm (contracts to expand thoracic cavity) accessory muscles: - sternocleidomastoid (contracts to elevate sternum) - pectorialis minor (contracts to pull the ribs outwards)

Question 170

Describe the ventilation mechanism of the lungs

Answer 170

INSPIRATION 1. external intercostal muscles contract. 2. internal intercostal muscles relax. 3. thus the ribs are moved upwards and outwards and the diaphragm down. 4. diaphragm muscles contract. 5. diaphragm descends and thus the rib cage rises. 6.thoracid cavity and intrapulmonary volume increases and so the pressure is reduced below atmospheric pressure and air flows in. EXPIRATION 1. external intercostal muscles relax. 2. internal intercostal muscles contract. 3. thus the ribs are moved downwards and inwards and the diaphragm up and the rib cage descends due to recoil of costal cartilages. 4. diaphragm muscles relax. 5. the volume of thorax and thus lungs decreases (elastic lungs recoil passively) and so the pressure is increased above atmospheric pressure and air flows out.

Question 171

Define and describe the symptoms, causes and consequence of emphysema

Answer 171

lung condition whereby the walls of the alveoli lose their elasticity due to damage to the alveolar walls symptoms: - loss of elasticity results in the abnormal enlargement of the alveoli leading to lower total surface area for gas exchange - degradation of the alveolar walls can cause holes to develop and alveoli to merge into huge air spaces (pulmonary bullae) cause: - major cause is smoking as the chemical irritants in cigarette smoke damage the alveolar walls - small proportion due to a hereditary deficiency of the elastase enzyme which breaks down the elastic fibers in the alveolar wall consequence: - shortness of breath - phlegm production - expansion of the ribcage - cyanosis - increased susceptibility to chest infections

Question 172

State the reason for human ventilation system

Answer 172

- as large organisms oxygen cannot diffuse into all the cells directly from the air - as land-borne organisms the gases need moist surfaces (membranes) to diffuse - to maintain a large concentration gradient between the alveoli and the blood

Question 173

State the reason for hemoglobin in the human respiratory system and its structure

Answer 173

because of the low solubility of O2 in water (and thus blood) it has difficulty with transport itself in animals relying on the circulatory system to deliver O2 has four polypeptide subunit chains each with cofacyor called a haeme group with an iron atom at its center each iron atom binds one molecule of O2 so one hemoglobin can carry four total

Question 174

Define the partial pressure of oxygen

Answer 174

pressure exerted by oxygen in a mixture of gases at low p02 hemoglobin is not fully saturated with O2 but at high full saturation occurs at high p02 it is easier to attach oxygen molecules to hemoglobin

Question 175

State the partial pressure of alveolar air and interpret it

Answer 175

about 100mmHg most of the hemoglobin molecules are bound to four O2

Question 176

Describe with reason the binding of O2 molecules to hemoglobin molecule

Answer 176

after the first O2 molecule binds to iron the hemoglobin molecule changes shape and thus more readily takes up two more molecules

Question 177

State when is the O2 separated from the hemoglobin molecules

Answer 177

when the oxygenated blood encounters a region where the PO2 in the interstitial fluid and body cells is lower than that in blood and thus it will diffuse from the blood plasma into the interstitial fluid and then into body cells

Question 178

State, name and explain the factor contributing to the release of O2 from hemoglobin

Answer 178

increased acidity in active tissues caused by oxidative reaction releasing CO2 which combines with water to form carbonic acid causing the Bhor effect - alteration of the hemoglobin conformation which will reduce the affinity for O2

Question 179

State the adaptation of the fetal hemoglobin

Answer 179

fetal hemoglobin is able to take up oxygen at lower partial pressures than adult hemoglobin because of its higher affinity for oxygen especially as the fetus obtains oxygen through the placenta as the oxygen dissociates from the mothers hemoglobin and is attached to the fetal hemoglobin

Question 180

State the function and adaptation of myoglobin

Answer 180

storage of oxygen in muscle tissues and its release when needed in respiration (gives also the muscle tissues its characteristic red colour) releases a lot of oxygen over a narrow range of low partial pressures in the tissues as it is more sensitive to a change in pO2 (higher affinity for oxygen at low pO2) and thus releases the oxygen into the tissues rapidly

Question 181

Describe the ways of carbon dioxide transport in the blood

Answer 181

1. dissolved in plasma (just 7-10%) 2. chemically bound to hemoglobin (just over 20%) - carries in the erythrocytes as carbaminohemoglobin (bound directly to the amino acids of globin not to the haeme) - CO2+Hb->HbCO2 3. bicarbonate ions in plasma (about 70%) - when dissolved CO2 diffuses into erythrocytes it combines with water forming carbonic acid (H2CO3) which as an unstable molecules dissociates into hydrogen ions and bicarbonate ions (carbonic anhydrase) CO2 + H20 -> H2CO3 -> H+ + HCO3- (arrows going both ways for both)

Question 182

Describe the export of hydrogen carbonate (and thus CO2) out of the red blood cell

Answer 182

hydrogen carbonate diffuses out through a carrier while chloride ions diffuse in (chloride shift) which maintains a balance of charges across the membrane the hydrogen ions attach to Hb which maintains pH and is know as buffering (additionally helped by the plasma proteins)

Question 183

State the importance of maintaining the blood pH and how that is achieved

Answer 183

pH 7.35-7.45 to avoid the onset of disease maintained by plasma proteins acting as buffers as they resist changes to pH by removing excess H+ ions or OH- ions through a) amino acids which are zwitterions - may have both a positive and negative charge and hence can buffer changes in pH b) the amine group may take H+ ions while carboxyl group can release H+ ions

Question 184

Describe the mechanism of homeostatic control of breathing

Answer 184

1. raise in the [CO2] in the blood and cerebrospinal fluid because of the increased metabolism. 2. increase in the [H+] lowering pH of the blood. 3. medulla oblongata detects the change in pH. 4. increase in the depth and rate of breathing through medulla's control circuits and its control of the rib muscles and diaphragm. 5. remain high until excess CO2 is eliminated in exhaled air and pH return to normal.

Question 185

State and name the effect of altitude on gas exchange

Answer 185

hypoxia thinner air at higher altitudes has a reduced pO2 and thus the uptake of oxygen will be reduced by normal ventilation since the hemoglobin cannot reach 100% saturation compensation by increased heart and breathing rate symptoms: headache, nausea, vomiting, dizziness, loss of consciousness, muscle weakness, rapid pulse

Question 186

State the remedy for altitude sickness

Answer 186

cclimatisation which helps the body produce more erythrocytes , myoglobin and mitochondra and a more adequate circulation around the muscles ventilation rate increases people living there have bigger chests, more dense alveoli, more red blood cells and higher affinity for oxygen

Question 187

Define an asthma attack

Answer 187

smooth muscle walls of the bronchi contract blocking air flow into the lungs is an allergic response to dust, pollen or house mites inhalers help through acting as bronchodilators

Question 188

Define a lung cancer and its effects

Answer 188

abnormal cell growth in the lung tissues caused by among else inhaling carcinogens (e.g. asbestos or radioactive ores) effects: - reduced surface for gas exchange - pressure on blood vessels and impeded transport - damage to pleural membranes, diaphragm or intercostal muscles

Question 189

Define sexual reproduction

Answer 189

process that creates a new organism by combining the genetic material of two organisms

Question 190

List and define the two main processes during sexual reproduction in eukaryotes

Answer 190

meiosis - number of chromosomes reduced from diploid 2n to haploid n fertilization - involves the fusion of two gametes to form a diploid zygote and the restoration of 2n chromosomes

Question 191

Define fertilization in animals

Answer 191

fusion of gametes to produce a new organism involves the fusion of an ovum (oocyte) with a sperm which leads to a development of an embryo

Question 192

State where are the gametes formed with distinction on testis and ovaries

Answer 192

gametes in general - gonads sperms in testis oocytes in ovaries

Question 193

Distinguish how the female vs male sexual characteristics (ovary and testis) are formed

Answer 193

female: 1. TDF is not produced in the absence of Y chromosome, which allows the cortex of the embryonic gonads to develop into ovaries 2. in the absence of testosterone the embryo develops female characteristics male: 1. the TDF (testis-determining factor) is produced by a gene on the Y chromosome which induced the medulla of the embryonic gonads to develop into testes 2. the testes produce testosterone which initiates the development of male sexual characteristics

Question 194

Define and list the three phases of gametogenesis and list its two "types"

Answer 194

the production of gametes 1. multiplication phase 2. growth phase 3. maturation phase spermatogenesis oogenesis

Question 195

Describe the process of spermatogenesis

Answer 195

1. the primordial germ cell in embryo divides mitotically to produce spermatogonia 2. some spermatogonia return to basement membrane and some grow to become primary spermatocytes. 3. FSH stimulates meiosis and thus primary spermatocytes divide into secondary spermatocytes. 4. LH stimulates testosterone production which induces meiosis II which produces 4 haploid spermatids. 5. testosterone stimulates differentiation of early spermatids into sperm cells

Question 196

List the processes counting as the differentiation of spermatids into sperm cells

Answer 196

- tail development - midsection with mitochondria - nourishment from Sertoli cells - storage and motility development in the epididymis

Question 197

Define ejaculation

Answer 197

passing of the sperm through the ejaculatory ducts and mixing of it with fluids from the seminal vesicles, the prostate and the bulbourethral glands to form semen

Question 198

State the components of semen with their places of origin

Answer 198

- seminal vesicles - yellowish viscous fluid rich in fructose (70% of semen) - prostatic secretion - whitish (clear sometimes), thin fluid containing proteolytic enzymes, citric acid, acid phosphate and lipids - bulbourethral glands - clear lubricating secretion into the lumen of the urethrae

Question 199

Describe the structure of the testis tissue

Answer 199

- testes composed of seminiferous tubules producing sperm. - each tubule surrounded by a basement membrane lined with germline epithelium cells. - germline epithelium will divide by mitosis to make spermatogonia. - developing spermatozoa are nourished by Sertoli cells - outside tubules the blood capillaries and interstitial cells (Leydig cells) produce testosterone.

Question 200

List the components of a single sperm cell

Answer 200

- head: acrosome with hydrolytic enzymes, DNA in nucleus - middle piece: helical mitochondria - tail

Question 201

Describe the process of oogenesis

Answer 201

1. primordial germ cell differentiates into oogonium through mitotic divisions. 2. oogonium undergoes mitosis to form a primary oocyte arrested in prophase of meiosis I until puberty (the ovary is functionally inactive). 3. the completion of meiosis I and onset of meiosis II creates a secondary oocyte arrested at metaphase of meiosis II and a polar body. 4. meiosis II is completed only if sperm penetrates the oocyte.

Question 202

List the phases of the menstrual cycle

Answer 202

- follicular phase - ovulation - luteal phase

Question 203

List the processes occurring during the follicular phase of the menstrual cycle

Answer 203

- stimulation of follicle growth by FSH - secretion of estrogen by the dominant follicle - inhibition of growth of other follicles by estrogen - stimulation of the endometrium development by estrogen

Question 204

List the processes occurring during the ovulatory phase of the menstrual cycle

Answer 204

- release of an egg through a surge of LH - creation of corpus luteum through rupture of the follicle

Question 205

List the processes occurring during the luteal phase of the menstrual cycle

Answer 205

- secretion of progesterone and estrogen by corpus luteum - stimulation of endometrium development by progesterone - inhibition of FSH and LH production by estrogen and progesterone - degradation of corpus luteum over time and dropping of progesterone alongside it - endometrium shedding in menstruation because of the lack of progesterone - as the FSH is no longer inhibited the cycle can start again

Question 206

State what hormone is released if a fertilization of an egg occurs in the menstrual cycle

Answer 206

release of HCG hormone by a zygote which maintains the corpus luteum

Question 207

Define and list an example of negative feedback

Answer 207

control process where the response to a stimulus reduced such stimulus e.g. LH is produced by pituitary (the stimulus) which promotes the formation of the corpus luteum which the produces progesterone (response) progesterone will inhibit LH secretion

Question 208

State the origin of the FSH hormone and its general function

Answer 208

o: pituitary gland promotes the development of follicles in the ovary and thus estrogen secretion by the follicle cells

Question 209

State the origin of the LH hormone and its general function

Answer 209

pituitary gland promotes ovulation and the formation of corpus luteum and thus estrogen secretion by the developing follicle

Question 210

State the origin of the estrogen hormone and its general function

Answer 210

o: developing follicle and corpus luteum in the ovary promotes thickening of the uterus lining inhibits secretion of FSH stimulates pituitary to secrete LH

Question 211

State the origin of the progesterone hormone and its general function

Answer 211

o: corpus luteum maintaining the thickened uterus lining inhibits secretion of both LH & FSH

Question 212

Distinguish the time of occurrence of spermatogenesis and oogenesis

Answer 212

spermatogonia are formed from the time of puberty throughout adult life oogonia formed in the embryonic ovaries long before birth

Question 213

Distinguish the time of formation of sperms and primary oocytes

Answer 213

sperms: daily primary oocytes: from puberty a few undergo meiosis II to become secondary oocytes each month but only one of them will become the ovulatory follicle the rest will degenerate

Question 214

Distinguish the number of sperms and ovum's formed in spermatogenesis and oogenesis

Answer 214

from 1 spermatogonium 4 sperms from 1 oogonium 1 ovum

Question 215

Distinguish the time of meiosis II completion in spermatogenesis and oogenesis

Answer 215

meiosis I and II go to completion during sperm production meiosis II reaches prophase and then stops until a male nucleus enters the secondary oocyte, triggering completion of meiosis II

Question 216

Distinguish the consequence for the egg if or if not fertilized

Answer 216

if: zygote begins to divide as it travels through oviduct to implant into lining of uterus if not: egg travels through oviduct to uterus and will exit body with blood and tissues during menstruation

Question 217

List the stages in the fertilization of a human egg

Answer 217

1. arrival of the sperm 2. binding 3. acrosome reaction

Question 218

Describe the stages of the fertilization of human egg

Answer 218

1. Arrival of sperm chemoattracted sperm swims up the oviduct to the egg. 2. Binding binding to the zona pellucida by the first sperm to break through the layers of follicle cells triggers acrosome reaction. 3.Acrosome reaction release of the contents of the acrosome through separation of the acrosomal cap from the sperm the proteases from the acrosome digest the route through the zona pellucida allowing the sperm to reach the plasma membrane of the egg 4. Fusion fusion of the plasma membranes of the egg and sperm and thus the nuclei of the egg and the sperm joins trigger of the cortical reaction 5. Cortical reaction exocytotic release of the contents of cortical granules as they move to the plasma membrane of the egg and fuse with it enzymes contained in them cause cross-linking of glycoproteins in the zona pellucida and thus making it hard (fertilization envelope forms) and preventing the entry of any more sperm - block to polyspermy 6. Mitosis a two cell embryo is produced through the sperate mitosis of both nuclei from the sperm and egg using the same centrioles and microtubular spindles

Question 219

Define polyspermy

Answer 219

condition in which multiple sperm nuclei enter the egg and fatally disrupt development

Question 220

Describe the process of early embryo development and implantation (until day 8-9)

Answer 220

1. zygote produced by fertilization in the oviduct starts to divide by mitosis. 2. formation of morula by several divisions. 3. simultaneous transport into the uterus by the oviduct. 4. morula develops into the blastocyst (hollow ball of cells). 5. implantation of the embryo into the endometrium

Question 221

Define morula

Answer 221

embryonic stage consisting of a solid, compact mass of 16 or more cells

Question 222

Distinguish between an early blastocyst and an implanting blastocyst

Answer 222

at 4 days the early blastocyst is basically a morula hollowed out and filled with fluid and hatches from the zona pellucida at 7 days the implanting blastocyst consists of a sphere of trophoblast cells (no zona pellucida) and an eccentric cell cluster called the inner cell mass

Question 223

Define a cleavage

Answer 223

process of the division of the zygote into a mass of daughter cells increasing the number of cells but not the size of the zygote

Question 224

Define a blastocyst

Answer 224

a hollow ball of cells developed from the morula

Question 225

Define implantation of an embryo

Answer 225

7 days after fertilization the embryo starts to become embedded in the endometrium

Question 226

State how the blastocyst embeds into the uterine wall

Answer 226

using enzymes to digest and penetrate the lining which will provide nourishment for the embryo until placenta develops

Question 227

State when and list and state the function of the two types of embryonic membranes formed

Answer 227

five weeks after fertilisation the amnion - encloses the embryo in a fluid - filled space the allantochorion - forms the fetal portion of the placenta

Question 228

State what happens with the 7,5 day blastocyst

Answer 228

the syncytiotophoblast is eroding the endometrium cells from the embryonic disc are now separated from the amnion by a fluid-filled space

Question 229

State what happens with the 12 day blastocyst

Answer 229

implantation is complete extraembryonic mesoderm is forming a discrete layer beneath the cytotrophoblast

Question 230

State what happens with the 16 day embryo

Answer 230

cytotrophoblast and associated mesoderm have become the chorion, the chorionic villi are elaborating embryo exhibits all three germ layers, a yolk sac, and an allantois (forms the basis of the umbilical cord)

Question 231

State what happens with the 4,5 week embryo

Answer 231

decidua capsularis, decidua basalis, amnion and yolk sac are well formed chorionic villi lie in blood-filled intervillous spaces within the endometrium embryo nourished via the umbilical vessels that connect it through the umbilical cord to the placenta

Question 232

Define the placenta

Answer 232

disc-shaped structure composed of maternal (endometrium) and fetal membrane tissues which form placental villi embedded in the uterus wall

Question 233

State how the blood flows in the placenta (and thus its functioning)

Answer 233

blood of the fetus flows close to the blood of the mother but they do not mix the umbilical cords conect the fetus to the placenta and maternal blood pools via open ended arterioles into intervillous spaces (lacunae) the chorionic villi extend into these spaces and facilitate the exchange of materials between the maternal; blood and fetal capillaries -> nutrients, oxygen and antibodies will be taken up by the fetus while carbon dioxide and waste products will be removed

Question 234

State the adaptations of placenta for diffusion

Answer 234

- huge surface area (lots of villi-like projections) - only a few cells thick - blood supplies keep the concentration gradients high - counter-current system

Question 235

Describe the placental circulation

Answer 235

maternal blood enters the placenta in the arteries, flows through blood, pools in the endometrium leaves via veins the embryonic blood remains which in vessels, enters the placenta through arteries, passes through capillaries in finger-like chorionic villi where it acquires oxygen and nutrients leaves the placenta through veins back to the fetus

Question 236

State how are materials exchanged between maternal and fetal blood

Answer 236

diffusion, active transport and selective absorption between the fetal capillary bed and the maternal blood pools

Question 237

List the placental structural adaptations to aid in its function

Answer 237

- rich blood supply (in fetus's blood vessels) - mothers arteries deliver blood into the intervillous space, bathing the villi of the placenta for maximal exchange of materials - few, thin membranes give a short diffusion path - villi increasing the surface for exchange - placenta equipped with a large surface area and many RER and vesicles for production of hormones - placenta secretes anti-immune substances to avoid attack by the immune system

Question 238

List the movements across the placenta

Answer 238

- respiratory gases (diffusion) - water (osmosis) - glucose (facilitated diffusion) - excretory products like urea - antibodies

Question 239

Define the placental barrier

Answer 239

cells separating maternal and fetal blood (selective and permeable)

Question 240

Define HCG and state its role

Answer 240

human chorionic gonadotropin a sex hormne which is intially secreted by the cells of the plastocyst and later from placenta maintaining the corpus luteum as an endocrine gland (secreting estrogen and progesterone) for the first 16 weeks of pregnancy later placenta takes its role as the estrogen and progesterone maintain the endometrium

Question 241

State the function progesterone and oxytocin during gestation

Answer 241

progesterone - inhibits secretion of oxytocin by the pituitary gland and inhibits contraction of the muscular outer wall of the uterus oxytocin - stimulates contraction of the muscular fibres in the myometrium

Question 242

State the mechanism of the role of hormones in parturition and the type of feedback it represents

Answer 242

positive feedback 1. towards the end of pregnancy there is a fall in progesterone level. 2. progesterone-driven inhibition of the uterus wall is removed & posterior pituitary releases oxytocin. 3. muscle in the uterus wall contract (directed by stretch receptors and signal to the pituitary gland to increase oxytocin secretion). 4. uterine contraction stimulate the secretion of more oxytocin. 5. uterine contractions become stronger and stronger. 6. cervix relaxes and becomes wider & amniotic sac bursts and the amniotic fluid is released. 7. fetus is pushed out through the cervix and vagina.

Question 243

List the steps of IVF

Answer 243

1. induced stop of the normal menstrual cycle. 2. hormone treatment to develop follicles (FSH to stimulate follicle growth and HCG for follicle maturation). 3. extract multiple eggs from ovaries 4. select the sperm and prepare (capacitate) and inject into egg via intra-cytoplasmic sperm injection 5. fertilization occurs under controlled conditions in vitro. 6. implantation of multiple embryos into uterus 7. test for pregnancy

Question 244

State the mechanism of pregnancy test functioning

Answer 244

a urine sample is applied -> hCG in the urine binds to the mouse antibodies and starts to travel up the paper into the test region. Antibodies that do not bind to hCG (there are always more antibodies than there is hCG) also move into and through the test region, where they serve as a positive control.​ In the Test Region, a second antibody to hCH (fixed to the paper so that it cannot move), stops the hCG and the original antibody bound to it. This is in the first window of the pregnancy test. Any antibodies that are not bound to hCH ('unbound' antibodies) continue to move up the test strip into the Control Region.​ In the Control Region, (the second window of the pregnancy test) the third antibody is encountered. The 'unbound' mouse antibodies are recognized by the goat antibodies fixed in the paper, and they stop moving at the second window

Question 245

Label the diagram of a male reproductive system.

Answer 245

- sperm duct - urethra - testis - penis - ureter - seminal vesicle - prostate gland - rectum - coiled tubes - scrotum - glans - foreskin - spermatic cord - bladder

Question 246

Label the diagram of a female reproductive system.

Answer 246

- right/left oviduct - ovary - uterus - vagina - bladder - urethra - clitoris - labia - vulva - rectum - vagina - cervix

Question 247

Explain what happens during spermatogenesis.

Answer 247

..

Question 248

Explain what happens during oogensis.

Answer 248

..

Question 249

Label the diagram of a sperm cell.

Answer 249

- acrosome - plasma membrane - haploid nucleus - helical mitochondria - microtubules in a 9+2 arrangement - protein fibres to strengthen the tail - tail

Question 250

Explain what happens during follicular phase, ovulation, luteal phase and menses.

Answer 250

..

Question 251

Label the structure of a female gamete.

Answer 251

- two centrioles - haploid nucleus - cytoplasm (or yolk) containing droplets of fat - first polar cell - plasma membrane - layer of follicle cells (corona radiata) - layer of gel composed of glycoproteins (zona pellucida) - cortical granules

Question 252

Label the diagram of fertilization and implantation process

Answer 252

- zygote - 4-cell stage - morula - early blastocyst - implanting blastocyst - ovulation - oocyte - fertilization

Question 253

Label the diagram of the uterus and placenta.

Answer 253

- uterus - placenta - umbilical cord - maternal blood pool - chorionic villus containing fetal capillaries - maternal arteries - maternal veins - maternal portion of placenta - fetal portion of placenta - umbilical arteries - umbilical vein - fetal arteriole - fetal venule

Question 254

State the homeostatic level in the human body and the factors responsible for maintaining it

Answer 254

- blood glucose concentration - 80 mg/dl - 110 mg/dl - pancreas and liver: insulin and glucagon - blood pH - 7.35-7.45 pH - buffering agents, kidneys through excretion and circulation breath and heart rate - 90% of blood volume is water - kidneys and hormones (excretion) - CO2 concentration 10-13 kPa - kidneys (excretion) & circulation - body temperature - 36-38 degrees - vasodilation and sweating for hot or vasoconstriction and shivering for cold

Question 255

State the general definition of the endocrine system

Answer 255

control system of ductless glands that secrete chemical messengers called hormones, which circulate within the body via the bloodstream to affect specific target cells at distant organs (does not include exocrine glands, which are ducted and secrete substances for release into cavities, either inside the body or onto its outer surface)

Question 256

State the three major chemical classes of hormones

Answer 256

- polypeptides - steroids - lipids that contain four fused carbon rings (all derived from the steroid cholesterol) - amines - synthesized from a single amino acid (tyrosine or tryptophan)

Question 257

Distinguish the hormone classes taking into account their philic properties

Answer 257

steroid - lipophilic - can cross membrane - constitutive secretion peptide and amine - hydrophilic - cannot cross the membrane - regulatory secretion

Question 258

Define regulatory secretion of hormones

Answer 258

cell stores hormone in secretory granules and releases them in "bursts" when stimulated

Question 259

Define constitutive secretion of human hormones

Answer 259

cell does not store hormone but secretes it from secretory vesicles as it is synthesized

Question 260

Distinguish the water-soluble hormone secretion and absorption into the cell from the lipid-soluble hormones

Answer 260

water-soluble 1. secreted by exocytosis and travel freely in the bloodstream. 2. cannot diffuse through the plasma membrane of target cells and thus they bind to cell-surface receptors to alter gene transcription. lipid-soluble hormones 1. diffuses out across the membranes of endocrine cells. 2. binds to transport proteins to keep them soluble in aqueous environment of the blood. 3. diffuses into target cells and typically binds to receptors in the cytoplasm or nucleus which will trigger a change in gene transcription.

Question 261

State the mechanism of functioning of steroids

Answer 261

1. steroid hormone diffuses through the plasma membrane and binds an intracellular receptor. 2. the receptor-hormone complex enters the nucleus. 3. the receptor-hormone complex binds a specific DNA region. 4. binding initiates transcription of the gene to mRNA. 5. the mRNA directs protein synthesis

Question 262

Describe the cyclic AMP second-messenger mechanism of water soluble hormones

Answer 262

1. hormone (1st messenger) binds receptor 2. receptor activates G protein (Gs) 3. G protein activates adenylate cyclase which converts ATP to cAMP (2nd messenger) 4. cAMP activates protein kinases which will trigger responses of target cells

Question 263

State the possible consequence of binding of the water-soluble hormone to a receptor protein

Answer 263

triggering the events at the plasma membrane that results in a cellular response such as: - the activation of an enzyme - a change in the uptake/secretion of specific molecules - rearrangement of the cytoskeleton - alteration of transcription of particular genes

Question 264

State the absorption pathway of the protein hormones

Answer 264

1. (are lipophobic) binds to receptors on the surface of the plasma membrane. 2. activates second messengers within the cell. 3. acts indirectly to change cellular activity via signal transduction pathways.

Question 265

State the main difference in the mode of hormone action

Answer 265

steroid hormones: cross the plasma membrane of their target cells and cause activation of a specific gene on a chromosome in the nucleus protein/peptide hormones: bind to a receptor in the plasma membrane of the target cell and thus activated receptor causes the release of a secondary messenger on the inside of the plasma membrane but the type of hormone remains outside the cell

Question 266

State the function of the neurosecretory cells of the hypothalamus

Answer 266

synthesis of the two posterior pituitary hormones: antidiuretic hormone (ADH) and oxytocin

Question 267

Define the posterior pituitary gland

Answer 267

an extension of the hypothalamus

Question 268

State an alternative name and general function of the antidiuretic hormone (ADH)

Answer 268

vasopressin regulates kidney function through increasing water retention in the kidneys, helping maintaining of normal blood osmolarity

Question 269

Describe the mechanism of osmoregulation of vasopressin

Answer 269

1. osmoreceptors in the hypothalamus monitor blood osmolarity via its effect on the net diffusion of water into/out of receptor cells. 2. blood osmolarity increases (after sweating for example) -> signals from the osmoreceptors -> release of ADH from the posterior pituitary (& thirst). 3. drinking water reduces blood osmolarity 4. inhibits also ADH secretion

Question 270

State the consequence of the failure in release of the sufficient ADH

Answer 270

condition: diabetes insipidus in which large quantities of dilute urine are produced

Question 271

Describe the consequence of ADH receptor binding to receptor molecules

Answer 271

increase in the number of aquaporin proteins inserted in the membranes of collecting duct cells and aquaporin channels recapture more water, reducing urine volume

Question 272

State the origin of secretion and function of oxytocin in female mammals

Answer 272

mammary glands regulates uterine contractions during birth stimulates the ejection of milk from the mammary glands of a nursing mother

Question 273

Describe the mechanism behind the regulation of milk ejection in a nursing mother

Answer 273

1. stimulation of nipples in suckling sends neuronal signals to the hypothalamus. 2. release of oxytocin from the posterior pituitary. 3. through positive feedback oxytocin stimulates more oxytocin secretion. 4. oxytocin stimulates the contraction of the smooth muscle cells surrounding individual alveoli of the mammary glands to contract and thus forcibly expels the milk through the nipples.

Question 274

State the factors controlling the release of anterior pituitary hormones and distinguish their types

Answer 274

hormones secreted by hypothalamus hypothalamic hormones can either be: - releasing hormone - inhibiting hormone depending on their role

Question 275

State the location of the pituitary gland relative to the hypothalamus and its main structural division

Answer 275

below the hypothalamus but connected to it two parts: anterior pituitary and the posterior pituitary lobe

Question 276

State what and how controls the activity of the pituitary gland and an alternative name for it

Answer 276

master hormone gland hypothalamus controls the endocrine activity of the pituitary gland through: releasing a number of hormones from neurosecretory cells into the portal vein running between the hypothalamus and anterior lobe releasing nerve impulses via neurons

Question 277

Distinguish the posterior pituitary from the anterior pituitary naming them, by which hormones they produce (list an example) and why are they released

Answer 277

posterior pituitary lobe - neurohypophysis - releases hormones produced by neurosecretory cells of the hypothalamus - released in response to nerve signals - examples: ADH anterior pituitary lobe - adenohypophysis - synthesizes hormones called releasing factors which will cause endocrine cells to release specific hormones into the bloodstream - are released into the portal vein extending to the anterior lobe - GnRH - triggers release of LH and FSH

Question 278

Describe the hormonal regulation of growth taking into account its hypo and hypersecretion

Answer 278

the growth hormone GH is secreted by the anterior pituitary and stimulates growth in humans through targeting the liver which responds through releasing insulin-like growth factors (IGFs), which circulate in the blood and directly stimulate bone and cartilage growth as well as increase in muscle mass hyposecretion: absence of GH the skeleton of an immature animal stops growing hypersecretion: during childhood can lead to gigantism (unusually tall person but retaining relatively normal body proportions)

Question 279

State the responsible agent for the release of melatonin and its control method

Answer 279

released by the pineal gland control of the release by a group of neurons in the hypothalamus called the suprachiasmatic nucleus (SCN)

Question 280

Describe the control of melatonin secretion by the SCN

Answer 280

1. photons stimulate the retina of the eyes 2. nerve impulse sent to SCN 3. nerve signal from SCN carried to the spinal cord and eventually to the pineal gland 4. inhibition of melatonin production 5. blood levels of melatonin fall, promoting wakefulness contrary if light levels decline melatonin production increases

Question 281

State the primary function of the thyroid hormones

Answer 281

increase in the metabolic rate control of the body temperature

Question 282

State the location of the thyroid gland

Answer 282

neck region, in front of trachea, below the larynx

Question 283

State the two hormones secreted by the thyroid gland and the amino acids they are synthesized from

Answer 283

thyroxine - T4 triiodothyronine - T3 synthesized from tyrosine and iodine

Question 284

Describe the role of thyroid hormones in vertebrates

Answer 284

- essential for normal growth and development - increase the rate of metabolism in the body tissues - generation of body heat - help regulate the synthesis of proteins necessary for cellular differentiation : 1. T3 binds with its receptor in the nucleus of target cell 2. T3-receptor complex induces or suppresses synthesis of specific enzymes and proteins

Question 285

Describe how the thyroid hormones regulate the temperature in the human body

Answer 285

HOTTER temperatures cause hypothalamus to inhibit thyroxin release (from thyroid), which decreases the metabolic rate of the body to reduce heat production (lower body temperature). COLDER temperatures causes hypothalamus to stimulate thyroxin release (from thyroid) which increases metabolic rate of the body to generate heat (raising body temperature).

Question 286

Define and describe the effects of hypothyroidism

Answer 286

thyroxin deficiency during infancy and childhood results in low metabolic rate leading to cretinism in adults drowsiness and sleepiness, mentally slow, little energy

Question 287

Define cretinism

Answer 287

a condition of retarred mental and physical development especially in children with hypothyroidism diagnosed early enough and treated with thyroid hormones can prevent the effects

Question 288

Define myxedema

Answer 288

condition of slowing down of physical and mental activity caused by almost no thyroid function and thus a drop in the basal metabolic rate by about 40% treated by oral administration of the hormone

Question 289

Define hyperthyroidism and state its consequence

Answer 289

excessive production of thyroid hormone by the thyroid gland consequence: Graves' disease an autoimmune disorder usually with symptomatic protruding eyes caused by fluid accumulation behind the eyes the body produces antibodies that bind to and activate the receptor for TSH causing sustained thyroid hormone production

Question 290

State the consequence of iodine deficiency

Answer 290

inability to synthesize adequate amounts of thyroid hormone thus insufficient to provide the usual negative feedback on the hypothalamus and anterior pituitary to inhibit TSH elevated TSH causes an enlargement of thyroid gland and thus neck swelling known as goitre

Question 291

Define leptin and its place of origin

Answer 291

hormone produced by the fat tissue throughout the body and regulating appetite

Question 292

Describe the leptin feedback control system

Answer 292

amount of leptin is proportional to the fat tissue reduced caloric intake -> decrease in fat tissue -> leptin signal decrease -> hypothalamus -> increased desire to eat

Question 293

State the organs and their corresponding actions regulating the appetite control center

Answer 293

pancreas -> carbohydrate/protein intake -> insulin released -> appetite inhibitory center activated adipose tissue -> lipids stored in fat cells -> leptin released -> block of stimulatory centre stomach -> empty -> release ghrelin -> stimulatory centre intestine -> food arrival -> PYY3-36 hormone -> inhibitory centre

Question 294

State the mechanism describing how resistance to insulin is related to obesity

Answer 294

type II diabetes could reduce the activity of the inhibitory neuron and reduce the amount of leptin released as such also resistance to leptin can develop and thus the blocking of the stimulatory neuron may fail to work leading to overeating and weight gain

Question 295

State how the hormones regulate the functioning of testes in males

Answer 295

FSH - initiates sperm production at puberty LH - stimulates the endocrine cells secreting testosterone

Question 296

State the normal blood glucose level in humans and how and why it can vary

Answer 296

90 mg/100 cm3 of blood - fasting or physical activity - drop to 70 mg - meal rich in carbohydrates - rise to 150 mg

Question 297

Describe the mechanism for regulation of blood glucose

Answer 297

digestion of carbohydrates -> glucose absorbed across the epithelial cells of the villi -> hepatic portal vein -> liver if too high levels -> withdrawn from the blood -> stored as glycogen

Question 298

Define hypoglycemia

Answer 298

blood glucose levels falling below 60 mg per 100 cm3 possible fainting if body and brain continue to be deprived of glucose -> convulsions and coma

Question 299

Define and describe hyperglycemia

Answer 299

an abnormally high concentration of blood glucose high concentration of blood glucose -> water potential of the blood plasma decreases -> water drawn from the cells and tissues by osmosis back to the blood -> volume of blood decreases -> water excreted by the kidney -> circulatory system deprived of fluid

Question 300

State and define the detection mechanism for excess blood glucose in the pancreas

Answer 300

the islets of Langerhans (alpha and beta) which are hormone secreting glands (endocrine glands) with rich capillary network but no ducts that would carry secretions away and thus their hormones are transported all over the blood by the body

Question 301

State the cells in the pancreas secreting insulin into the blood

Answer 301

beta islets of Langerhans

Question 302

State the cells in the pancreas secreting glucagon into the blood

Answer 302

alpha islets of Langerhans

Question 303

State the basic role of insulin

Answer 303

enhancing the transport of glucose into body cells stimulation of the liver to store glucose as glycogen (glucose levels falls)

Question 304

State the basic role of glycogen

Answer 304

promotes the breakdown of glycogen in the liver and thus the release of glucose into the blood

Question 305

List the sites of blood glucose regulation

Answer 305

- liver (storage as glycogen) - pancreas (insulin & glucagon) - muscles (can import glucose but nor export) - brain cells (import and use of glucose) - small intestine (glucose absorption) - most tissues

Question 306

State the molecular reason for type I diabetes

Answer 306

insulin is not produced by beta cells in the pancreas and hence glucose is not removed from the bloodstream causing diabetes

Question 307

State the molecular reason for type II diabetes

Answer 307

prolonged overproduction of insulin leads to desensitization of the insulin receptors and hence glucose is not removed from the bloodstream, causing diabetes (defect in signaling between the insulin receptor and the glucose transporter Glut-4)

Question 308

State the normal molecular physiology of glucose removal from the bloodstream

Answer 308

insulin bind to insulin receptors and triggers the opening of glucose transporters in fat and muscle cells glucose removal from the bloodstream

Question 309

Define diabetes in general

Answer 309

name for the group of diseases in which the body fails to regulate blood glucose levels carries an increased risk of circulatory disorders, renal failure, blindness, strokes and heat attacks

Question 310

Distinguish type I diabetes from type II in terms of onset of disease and treatment type

Answer 310

type I: onset during childhood type II: onset after childhood type I: insulin injections to control glucose levels, diet is not enough type II: insulin injections are not needed, low carbohydrate diet

Question 311

Define an endotherm and list the two animal categories being such

Answer 311

organism producing heat through internal means such as muscle shivering or increasing its metabolism and controlling heat loss through the skin mammals and birds opposite of endothermy is exothermy.

Question 312

How does the hypothalamus gather the signals from the body

Answer 312

constant monitoring of blood composition circulating through the capillary networks of the hypothalamus sensory receptors located in key organs in the body sensory neurons via the spinal cord

Question 313

State the origin of heat production in the human body

Answer 313

biochemical reactions of metabolism generating heat as waste product and distributing it by the blood circulation over 70% comes from the core organs (kidneys and heart) also lungs and brain during physical activity the skeletal muscles also do a good job

Question 314

List the factors controlling the body temperature in humans

Answer 314

- transfer of heat in the blood - role of the hypothalamus - role of sweat glands - role of skin arterioles - shivering

Question 315

State the body part responsible for thermoregulation

Answer 315

hypothalamus

Question 316

List the actions of the hypothalamus relating to the heat conversion and loss centre

Answer 316

CORE TEMPERATURE IN BLOOD DECREASE hypothalamus - heat conversion centre - vasoconstriction - increased metabolic rate - shivering - hair raised INCREASE hypothalamus - heat loss centre - vasodilation - decreased metabolic rate - sweating - hair lowered

Question 317

State the role of the thyroid hormone

Answer 317

regulation of bioenergetics; maintaining normal blood pressure, heart rate and muscle tone, regulation of digestive and reproductive functions

Question 318

Describe the hormone cascade pathway of thyroid regulation

Answer 318

1. thyroid hormone levels drop below the normal range. 2. hypothalamus secretes TRH (thyrotropin releasing hormone) into the blood. 3. portal vessels carry TRH to the anterior pituitary. 4. TRH causes anterior pituitary to secrete TSH (thyroid-stimulating hormone) into the circulatory system. 5. TSH stimulates endocrine cells in the thyroid glands to secrete thyroid hormones (T3 and T4). 6.thyroid hormone levels increase in the blood returning to normal range. 7. acts on target cells throughout the body to control bioenergetics. 8. thyroid hormone blocks TRG release - negative feedback loop

Question 319

List the main functions the nervous system

Answer 319

- coordination of information from the senses as well responses to the sensory information - coordination of muscle activity - monitoring of the functioning of the other organ systems

Question 320

State the organization of neurons

Answer 320

into central nervous system and peripheral nerves linking sense organs, muscles and glands with the brain or spinal cord

Question 321

State the specialization of neuron cells

Answer 321

for the transmission of information in the form of impulses

Question 322

List the ways of conducting nerve impulses

Answer 322

- from receptors to the CNS by sensory neurons - within the CNS by relay neurons - from the CNS to effectors by motor neurons

Question 323

State the overall structural components of each neuron

Answer 323

a cell body - with nucleus and most organelles variable number of nerve fibres: - dendrites - axons

Question 324

Distinguish dendrites from axons in terms of function

Answer 324

dendrites - conduct impulses toward the cell body axons - conduct impulses away from the cell body (thinner than dendrites, longer)

Question 325

Define a Schwann cell

Answer 325

supporting cell of the neuron which wraps around the axon of motor neurons and form myelin sheath

Question 326

Define the node of Ranvier

Answer 326

junction along the myelin sheath, between the individual Schwann cells

Question 327

List and define the main types of neurons

Answer 327

- sensory neurons - carry impulses from receptors to the spinal cord and the brain - interneurons - relay impulses from one neuron to another in the brain and spinal cord - motor neurons - carry impulses from the brain and spinal cord to effectors (usually muscles)

Question 328

State the path of a nerve signal from the receptor to the effector

Answer 328

receptor (e. g. sense organ) -> sensory neurons -> CNS (relay neurons) -> motor neurons -> effectors

Question 329

Define an effector

Answer 329

organ of the body (muscle/gland) responding to an impulse from a motor neuron

Question 330

Define and state an exact value of the resting potential of the neuron

Answer 330

potential difference across a nerve cell membranes when it is not being stimulated -70 mV (millivolts)

Question 331

List the reasons for the existence of resting potential in neurons

Answer 331

- sodium/potassium pump actively transports Na+ ions out of the cell and K+ ions inside (3 Na+ for 2 K+) - membrane more permeable (50 times) to K+ ions than Na+ ions and so the diffusion down the concentration gradient is facilitated - higher concentration of organic anions found on the inside of the membrane

Question 332

Define and state an exact value of the action potential of the neuron

Answer 332

potential difference produced across the plasma membrane of the nerve cells when stimulated (through depolarization) +40 mV

Question 333

Describe depolarization in the neuron

Answer 333

1. brief opening of the sodium gated facilitated diffusion channel by the stimulus. 2. few sodium ions diffuse into the axoplasm. 3. axoplasm less negative 4. a) insufficient sodium ions diffuse in it and thus failure of reaching of the threshold potential and return to the resting potential b) reaching of the threshold potential and thus change from a negative potential to a positive potential

Question 334

Distinguish initial recovery from complete recovery after the electric stimulus in a neuron

Answer 334

initial recovery: - closing of the voltage gated sodium channels - opening of the sodium gated potassium channels - increased flow of potassium ions diffusing down the concentration gradient full recovery: - all voltage gated channels closed - sodium-potassium pump removing sodium ions from axoplasm - diffusion of potassium ions through open channel

Answer 335

1. resting potential - both Na+ and K+ channels are closed. 2. Na+ channels open and Na+ rush in by diffusion. 3. interior of the axon more positively charged. 4. Na+ ions close 5. K+ ions open and K+ rush out by diffusion. 6. interior of the axons starts to become less positive again. 7. re-establishment of the resting potential by the Na+/K+ pump starting to work

Question 336

State the steps of the nerve signal impulse

Answer 336

1. Resting state. No ions move through voltage-gated channels. 2. Depolarization is caused by Na+ flowing into the cell. 3. Repolarization is caused by K+ flowing out of the cell. 4. Hyperpolarization is caused by K+ continuing to leave the cell.

Question 337

Define and state the function of the saltatory conduction

Answer 337

in myelinated axons, jumping of the action potential from node to node. because the voltage-gated sodium channels are restricted to nodes of Ranvier and the extracellular fluid is in contact with the axon membrane only at the nodes thus action potentials are not generated in the regions between the nodes (Myelin layer prevents the movement of Na+/K+ ions) which speeds up the rate of transmission

Question 338

State and distinguish the two types of synapses

Answer 338

electrical synapse - gap junctions, formed from the presynaptic and postsynaptic cells, enable the flow of ions through them - directly passing impulses chemical synapse - plasma membranes of the presynaptic and postsynaptic cells are separated by the synaptic cleft through which the neurotransmitter molecules diffuse and bind to receptors in the plasma membrane of the postsynaptic cell. binding opens channels to ion flow which may generate an impulse in the postsynaptic cell

Question 339

State the structural parts of the chemical synapse

Answer 339

- synaptic knob - the swollen tip - pre-synaptic neuron - axon of one neuron - post-synaptic neuron - dendrite and cell body of another neuron - synaptic cleft - gap between the neurons

Question 340

Define transmitter substances

Answer 340

small diffusible molecules, produced in the golgi apparatus in the synaptic knob and held in tiny vesicles before crossing the synaptic cleft (with the action potential)

Question 341

List the examples of transmitter substances in a human neuron

Answer 341

- acetylcholine - released by cholinergic neurons - noradrenalin - adrenergic neurons - glutamic acid - dopamine

Question 342

Describe in steps the chemical synapse transmission

Answer 342

1. arrival of an action potential at the synaptic knob. 2. calcium ion channels in the pre-synaptic membrane open. 3. calcium ions flow in from the synaptic cleft. 4. Ca2+ ions cause fusion of the vesicles of transmitter substance with the pre-synaptic membrane. 5. release of the substance into the synaptic cleft 6. diffusion of the transmitter substance across the synaptic cleft 7. binding with receptor protein and thus triggering the entry of Na+ ions and thus action potential in the post-synaptic membrane. 8. transmitter substance on the receptors is inactivated by enzyme action which closes the ion channel of the receptor protein 9. re-establishment of the resting potential in the post-synaptic neuron. 10. re-synthesis of the inactivated products from the transmitter into transmitter substance and their packaging for re-use.

Question 343

Describe the blocking of the synaptic transmission and give a specific example

Answer 343

mimicking of the neurotransmitters and thus stimulating the synapse even in the absence of the normal neurotransmitter inhibition - inhibitor molecule binds to he postsynaptic receptor but does not cause depolarization - normal neurotransmitter cannot bind e.g. inhibitory neonicotinoid pesticide binding to acetyl choline receptors

Question 344

State the all-or-nothing principle of neuronal stimulation

Answer 344

stimulus must be at or above minimum intensity - the threshold of stimulation - in order to initiate action potential every subthreshold stimuli will cause the influx of sodium ions to be quickly reversed and the full resting potential to be re-established

Question 345

State the way of the intensity of the stimulus increasing

Answer 345

increase in the frequency of the action potential passing along the fibers (same strength of the individual action potentials) recognized by the effector or the brain

Question 346

Define and state the reason for the refractory period

Answer 346

the 5-10 millisecond period after the excitation of a neuron, when the neuron fibre is not excitable. because large excess of sodium ions inside the fibre and thus impossible further influx

Question 347

Distinguish the CNS from the PNS in terms of their components

Answer 347

CNS: brain and spinal cord PNS: cranial and spinal nerves

Question 348

State the function of the autonomic nervous system

Answer 348

visceral motor - involuntary conducts impulses from the CNS to cardiac and smooth muscles and glands

Question 349

Distinguish the sympathetic division from the parasympathetic division and state the system they are both part of

Answer 349

both part of ANS sympathetic: mobilizes body systems during activity parasympathetic: conserves energy and promotes house-keeping function during rest

Question 350

State the cause of an infectious disease

Answer 350

another organism/virus invades the body and lives there parasitically

Question 351

Distingusih communicable from non-comunicable diseases and list their alternative names

Answer 351

infectious diseases (communicable) - pathogens may pass from diseased host to a healthy organism non-infectious diseases (non-communicable) - non infectious lol (cardiovascular etc)

Question 352

List the types of pathogens

Answer 352

- microorganisms - some bacteria, fungi - some protozoa - flatworms, roundworms - all viruses

Question 353

Define immunity

Answer 353

the ability to resist infection

Question 354

State and define the two types of immunity

Answer 354

non-specific immunity - allows the body to resist infections by a wide range of pathogens specific immunity - allows the body to resist infections by a specific pathogen

Question 355

State the types of non-specific immunity

Answer 355

- external barrier - skin - internal barriers - phagocytic cells

Question 356

State the two types of internal barriers

Answer 356

- mucous and cilia - gastric juice containing hydrochloric acid killing many bacteria present in the food

Question 357

Define specific immunity

Answer 357

proteins and other molecules on the surface of pathogens recognized as the foreign by the body and stimulate a specific immune response

Question 358

State and define the two types of animal immunity

Answer 358

innate immunity - recognition of traits shared by broad ranges of pathogens, using a small set of receptors - rapid response adaptive immunity - recognition of traits specific to particular pathogens, using a vast array of receptors - slower response

Question 359

State the types of innate immunity

Answer 359

- barrier defenses - internal defenses

Question 360

List the types of barrier defenses

Answer 360

- skin - mucous membranes - secretions

Question 361

List the types of internal defenses

Answer 361

- phagocytic cells - natural killer cells - antimicrobial proteins - inflammatory response

Question 362

List and define the types of adaptive response

Answer 362

humoral response - antibodies defend against infections in body fluids - B cells cell-mediated response - cytotoxic cells defend against infections in body cells - T cells

Question 363

State the types of barriers of the specific immune system

Answer 363

- physical - skin and mucus membranes - chemical - stomach acidity, anti-microbial peptides - cellular - macrophages, neutrophils

Question 364

State the first line of defense against pathogens

Answer 364

skin

Question 365

State and justify the type of barrier the skin is

Answer 365

physical - covered by keratinized protein of the dead cells of the epidermis - tough and impervious layer chemical - sebum secreted by sebaceous glands - maintaining the skin moisture and lowering the skin pH which inhibits the growth of bacteria and fungi

Question 366

List the examples of chemical barriers

Answer 366

- lysozyme - phospholipase A (saliva and tears) - acid pH - stomach - anti-fungal peptides - alpha-defenses - intestinal tract - anti-microbial peptides - beta-defenses - respiratory, urogenital tract

Question 367

State the steps of immunity direct response after tissue damage

Answer 367

1. release of vasoactive and chemotactic factors (histamines) by the mast cells. 2. triggering a local increase in blood flow and capillary permeability. 3. influx of fluid (exudate) and cells. 4. phagocytes migrate to the site of inflammation (chemotaxis). 5. destroying of bacteria by phagocytes and antibacterial exudate.

Question 368

Define platelets

Answer 368

small cell fragments, which form in the bone marrow and circulate in the blood stream until they stick to the damaged tissues and clump together

Question 369

Describe the clotting cascade of events

Answer 369

1. damage to the endothelium vessel exposing connective tissue in the vessel wall to blood. 2. platelets adhere to the collagen fibers in the connective tissue. 3. platelets release a substance that makes nearby platelets sticky. 4. platelets form a plug providing immediate protection against blood loss. 5. usually plug is reinforced by a fibrin clot

Question 370

Describe the fibrin clot formation

Answer 370

1. mixing of the clotting factors released from the clumped platelets or damaged cells with clotting factors in the plasma forming an enzymatic cascade. 2. conversion of the plasma protein photothrombin to its active form thrombin (enzyme). 3. catalysis of the final step of the clotting process - conversion of fibrinogen to fibrin. 4. threads of fibrin become interwoven into the clot

Question 371

List the players of innate immune responses

Answer 371

- neutrophils - macrophages - dendritic cells - natural killer cells

Question 372

State the function of neutrophils

Answer 372

phagocytosis of: - reactive oxygen and nitrogen species - antimicrobial peptides

Question 373

State the function of macrophages

Answer 373

phagocytosis of inflammatory mediators antigen presentation reactive oxygen and nitrogen species cytokines complement proteins

Question 374

Define neutrophils

Answer 374

most abundant type of white blood cell, phagocytic upon encountering infectious material in the tissues

Question 375

State the second line of immune defense

Answer 375

phagocytosis

Question 376

Describe the steps of phagocytosis

Answer 376

1. phagocytic leukocytes circulate in the blood and in response to infection move into body tissues - extravasation. 2. because the damaged tissues release chemicals (f.e. histamine) which attracts leukocytes via chemotaxis. 3. phagocyte adheres to pathogens or debris. 4. phagocyte forms pseudopods that engulf the particles - formation of phagosome. 5. lysosome fuses with the phagocytic vesicle forming a phagolysosome. 6. lysosomal enzymes digest the particles leaving a residual body 7. exocytosis of the vesicle removes indigestible and residual material. 8. pathogen fragments on the surface of the phagocyte in order to stimulate the third line of defense.

Question 377

State the third line of immune defense

Answer 377

specific immunity

Question 378

Define and state the full name of MHC

Answer 378

major histocompatibility complex a glycoprotein encoded by a large gene family in all vertebrates and unique to every individual (genetically determined) each individual has unique MHC antigens present on the plasma membrane of most of ones body cells

Question 379

State the mechanism through which lymphocytes differentiate their own antigens from the foreign ones

Answer 379

through antigen receptors recognizing the MHC receptors each recognizes one specific antigen and in its presence will divide rapidly producing many clones of itself then the cloned lymphocytes secrete the antibodies specific to that antigen

Question 380

State the two categories of lymphocytes with their place of differentiation and function

Answer 380

B-lymphocytes - differentiate in the bone marrow - secrete antibodies (humoral immunity) as one particular B-cell produces one particular type of antibody T-lymphocytes - differentiate in the thymus - cell mediated immunity - become activated when other cells of the immune system atack foreign cells directly and kills them

Question 381

State the origin of B- and T- cells

Answer 381

in red bone marrow

Question 382

Define immunocompetence

Answer 382

ability of the B- and T-cells to recognize one specific antigen

Question 383

State the feature enabling immunocompetence

Answer 383

specific receptor protein on the cell surface capable of binding to one type of antigen

Question 384

Describe the maturation of the B- and T-cells

Answer 384

- lymphocyte precursors destined to become T cells migrate in blood to the thymus and mature there - B cells mature in the bone marrow - development of immunocompetence and self-tolerance

Question 385

State what happens within the lymph nodes

Answer 385

pathogens and foreign particles in the circulating lymph encounter and activate macrophages and other cells that carry out defensive actions

Question 386

State the function and full name of APCs

Answer 386

antigen-presenting cells engulf antigens and than present small fragments of them like signal flags on their own surfaces where T cells can recognize them

Question 387

State how are T cells activated

Answer 387

by the antigens presented to them on MHC proteins by APCs

Question 388

Describe the production of antibodies (in stages)

Answer 388

1. antigen enters the body 2. antigen binds to antibody on B-cell plasma membrane 3. antigen is taken up by exocytosis of the B-cell 4. is expressed on the plasma membrane at the MHC protein 5. simultaneously macrophages engulf antigens by endocytosis and express it on their MHC proteins on the plasma membrane (antigen presentation) 6. T-cell binds briefly to macrophage that presents an antigen causing activation (now is called activated helper T-cell) 7. activated helper T-cell now binds to B-cell with the same expressed antigen causing its activation (activated B cell) 8. the activated B-cell divides rapidly forming a clone of plasma cells. 9. some activated B-cells and T-cells survive in the body as memory cells. 10. each plasma cell now mass-produces antibody molecules and secretes them by exocytosis antibodies overcome the antigen by f. e. neutralising it

Question 389

State the function of memory B and T cells

Answer 389

initiating a more speedy response in the event of re-infections

Question 390

State a way of overcoming an antigen by the antibodies through neutralization

Answer 390

clumping together of cells to aid engulfing by other macrophages precipitation of soluble antigens

Question 391

State when are cytokines released

Answer 391

after activation of helper T lymphocytes by the antigen presentation

Question 392

State the function of cytokines

Answer 392

stimulation of a specific B-cell that produces antibodies to the antigen to divide and form clones

Question 393

State the two main functions of the clones created by B-cells

Answer 393

development into short-lived plasm cells that produce large quantities of a specific antibody (most of them) differentiation into long-lived memory cells that function to provide long-term immunity (some of them)

Question 394

Define an antibody with its structure in mind

Answer 394

a special protein called immunoglobin made of four polypeptide chains held together by disulphide bridges with a unique arrangement of amino acids residues in the polypeptide forming the fork region (binding site of the antigen)

Question 395

State the initial location of antibodies

Answer 395

attached to the plasma membrane of B-cells

Question 396

State the location of antibodies after B-cell activation

Answer 396

mass-produced and secreted by cells derived from the B-cells by exocytosis

Question 397

Define clonal selection

Answer 397

product of vast numbers of identical plasma cells

Question 398

Define a polyclonal response

Answer 398

because invading microorganisms have many different types of antigens a typical pathogen activated many different types of B-cells and thus triggers the secretion of many different antibodies all of which attach and attract that pathogen

Question 399

State the consequence of a polyclonal response

Answer 399

more efficient destruction of the pathogen

Question 400

List the types of modes of action of antibodies

Answer 400

- precipitation - agglutination - neutralization - inflammation - opsonization - activation of the complement

Question 401

Define opsonization

Answer 401

mode of action of antibodies - making a pathogen more recognizable to phagocytes so as they are more readily engulfed

Question 402

Distinguish the neutralization of viruses/bacteria from the naturalization of toxins by the antibodies

Answer 402

viruses/bacteria - prevention of docking to host cells so that they cannot enter the cells toxins - binding to toxins produced by pathogens, preventing them from affecting susceptible cells

Question 403

Define agglutination by the antibodies

Answer 403

sticking together of pathogens so as to prevent them from entering cells and making them easier for phagocytes to ingest the large agglutinated mass can be filtered by the lymphatic system and phagocytised

Question 404

State the characteristics of the secondary immune response

Answer 404

faster, more prolonged and more effective

Question 405

State what do memory cells provide

Answer 405

immunological memory

Question 406

State the mechanism of function of vaccines

Answer 406

induction of long-term immunity to a specific pathogenic infection by stimulating the production of memory cells

Question 407

Define a vaccine

Answer 407

weakened or attenuated form of the pathogen consisting of antigens but incapable of triggering the disease

Question 408

State the function of an adjuvant in a vaccine

Answer 408

the antigenic determinants in the vaccine may be conjugated to it boosting the immune response

Question 409

State the body's response to a vaccine injection

Answer 409

initiation of the primary immune response an in consequence making of the memory cells

Question 410

Distinguish the B from T lymphocytes in terms of type of immune response triggered

Answer 410

B-cells - humoral T-cells - cellular

Question 411

Distinguish the B from T lymphocytes in terms of primary targets of immune response

Answer 411

B-cells - extracellular pathogens (bacteria, fungi etc) T-cells - intracellular pathogens (virus infected cells) and cancer cells

Question 412

State the antigens present in the red blood cells and the blood compatibles for blood type A

Answer 412

A antigen compatible: A, O

Question 413

State the antigens present in the red blood cells and the blood compatibles for blood type B

Answer 413

B antigen comp: B, O

Question 414

State the antigens present in the red blood cells and the blood compatibles for blood type AB

Answer 414

both A and B antigens compatible: A, B, AB, O (with AB+ as the universal recipient)

Question 415

State the antigens present in the red blood cells and the blood compatibles for blood type O

Answer 415

none antigens only O compatible (universal donor)

Question 416

State the consequence of an incompatible blood transfusion

Answer 416

antigens on the surface of red blood cells stimulate antibody production in a person with a different blood group and thus trigger agglutination and hemolysis of the red blood cells

Question 417

Distinguish the RH positive from negative blood group

Answer 417

Rh factor (spikes on rbc) which makes it positive Rh negative = no spikes

Question 418

Describe the serological conflict

Answer 418

..

Question 419

Define active humoral immunity

Answer 419

B-cells encounter antigens and produce antibodies against them

Question 420

Define passive humoral immunity

Answer 420

ready antibodies are introduced into your body thus the B-cells are not challenged by antigens (immunological memory does not occur) and the protection provided by the "borrowed" antibodies ends when they naturally degrade in the body

Question 421

List the two types of passive humoral immunity

Answer 421

naturally acquired - antibodies passed from mother to fetus via placenta or to infant in her milk artificially acquired - injection of exogenous antibodies (gamme globulin)

Question 422

List the two types of active humoral immunity

Answer 422

naturally acquired - infection (contact with pathogen) artificially acquired - vaccine

Question 423

Define an allergen

Answer 423

environmental substance that triggers an immune response despite not being intrinsically harmful

Question 424

Define anaphylaxis

Answer 424

severe systemic allergic reaction, can be fatal if left untreated

Question 425

State the location of the immune response to the allergen (allergic reaction)

Answer 425

localized at the region of exposure (e.g. airways and throat)

Question 426

State the requirement for an allergic reaction to occur

Answer 426

pre-sensitized immune state (prior exposure to the allergen)

Question 427

State the mechanism of an allergic reaction

Answer 427

- B-cell first encounters the allergen - making of large quantities of antibody (IgE) through differentiating of the B cell into plasma cells - IgE antibodies attach to mast cells priming them towards the allergen - upon re-exposure to the allergen - release of large amounts of histamine by the IgE-primed mast cells - inflammation as a cause

Question 428

State the consequences of the histamine release from the IgE-primed mast cells in response to an allergen

Answer 428

- capillary widening - increased blood flow - increased permeability - fluid release into tissues - redness and swelling - attraction of leukocytes - extravasation of leukocytes to site of injury - tenderness - systemic response - fever and proliferation of leukocytes - pain

Question 429

Define a monoclonal antibody

Answer 429

artificially produced antibody to target one specific antigen as usually the body produces a polyclonal response to an invasion by pathogen

Question 430

State the possible use of a monoclonal antibody

Answer 430

cancer treatment as the cancer cells carry specific antigens (tumor-associated antigens TAA) on their cell surfaces thus if monoclonal antibodies to TAA are produced the drugs to kill cells or the inhibitors to block key tumor proteins can be attached and the cancer cells specifically targeted and killed

Question 431

State the result of the use of monoclonal antibodies on cancer cells

Answer 431

hybridization of the tumor cell and the specific B cell resulting in hybridoma capable of synthesizing large quantities of antibodies that can be used in various technologies

Question 432

Define a myeloma cell

Answer 432

cancerous tumor of a plasma cell which will divide rapidly but not produce antibodies

Question 433

Define antibiotics

Answer 433

naturally occurring substances that slow or kill microorganisms

Question 434

Define broad spectrum antibiotics

Answer 434

antibiotics effective over a wide range of pathogenic organisms

Question 435

State the principle of the antibiotic mechanism of work

Answer 435

interfering with the specific metabolic processes, typically the synthesis and laying down of new wall materials

Question 436

Describe the process of infection by an HIV virus

Answer 436

1. binding of the virus to the T-lymphocyte cell and passing of the viral core into the cell 2. RNA and viral enzymes are released 3. reverse transcriptase catalyzes the copying of the genetic code of each of the viruses RNA strand into a DNA 4. the DNA enters the host nucleus and is spliced into the hosts DNA of a chromosome 5. may be replicated with the hosts genes every time the host cell divides (but remain latent giving no sign of presence) 6. some events activate the HIV genes and the outcome is AIDS 7. so the synthesis of the viral messenger RNA which passes out into the cytoplasm and codes for viral proteins at the ribosomes 8. viral RNA, enzymes and coat proteins are formed into viral cores 9. viral cores move against the cell membrane and bud-off new viruses which will infect other lymphocytes and repeat the cycle

Question 437

State the consequence of the HIV infection

Answer 437

AIDS and thus dramatic loss in the ability to produce antibodies to a wide range of common infections (e.g. pneumonia, meningitis)

Question 438

List the possible ways of infecting with an HIV virus

Answer 438

- sexual intercourse - sharing of hypodermic needles - breast feeding of a newborn - blood transfusion and organ transplants

Question 439

State the current treatment for the HIV virus infection

Answer 439

drugs such as AZT and two protease inhibitors that reduce the number of HIV-infected cells by interrupting the steps of nucleic acid reverse transcription

Question 440

State the consequence and function of the recognition of the self-antigens by the T cells

Answer 440

apoptosis as it eliminates the self-reactive T cells that could cause autoimmune diseases

Question 441

State the consequence of the failure of the recognition of the self-antigens by the T cells

Answer 441

survival and continued maturation

Question 442

State the consequence and function of the recognition of the self-MHC by the T cells

Answer 442

survival and proceeding to negative selection

Question 443

State the consequence of the failure of the recognition of the self-MHC by the T cells

Answer 443

apoptosis

Question 444

State the steps of the T-cell education in the thymus

Answer 444

1. positive selection (self MHC) 2. negative selection (self antigens)

Question 445

Describe the diagnosis of an HIV infection using monoclonal antibodies

Answer 445

1. HIV antigen attached to the plate. 2. patients serum passed over the plate. 3. HIV antibody would attach to the antigen on the plane. 4. second antibody, specific to the HIV antibody, passed over the plate. 5. antibody will attach to the concentrated HIV antibody on the plate (second antibody has an enzyme attached to its structure). 6. Chromagen dye passed over the complex. 7. enzyme will turn the Chromagen to a more intense colour the more antibodies the greater the HIV antibody level

Question 446

Define excretion and list main excretory compounds in mammals.

Answer 446

removal from the body of the waste products of metabolism nitrogenous compounds such as urea, ammonia and uric acid coming from breakdown of proteins, nucleic acids and excess amino acids

Question 447

Define osmoregulation

Answer 447

control of proper balance of water and dissolved substances (inorganic ions) in the organism

Question 448

List the main functions of the kidney

Answer 448

1. excretion of urea 2. regulation of the amount of water that is retained and excreted in the body. 3. plasma filtration to get rid of certain ions and wastes while keeping other ions and maintaining water balance. 4. maintaining the pH balance throughout the body. 5. production of the EPO hormone. 6. assisting with increased and decreased blood pressure.

Question 449

State the full name and brief function of EPO hormone

Answer 449

erythropoietin role in production of red blood cells

Question 450

State the function of ureter

Answer 450

transport of urine to the bladder

Question 451

State the way that blood is carried to the kidney and taken away

Answer 451

in by renal artery away by renal vein

Question 452

Define a nephron

Answer 452

basic unit structure of the kidney

Question 453

List the steps of formation of urine

Answer 453

1. ultrafiltration in the renal capsule. 2. selective reabsorption in proximal convoluted tubule. 3. water conservation in the loop of Henle. 4. secretion in distal convoluted tubule. 5. water reabsorption in the collecting ducts. 6. ADH and the formation of concentrated/dilute urine.

Question 454

State the three layers the ultrafiltration filtration takes place through

Answer 454

- endothelium of the blood capillary - basement membrane of the blood capillaries - epithelium of the renal capsule

Question 455

Define glomerular filtration

Answer 455

blood from the renal artery enters the afferent arteriole which then turns into even smaller capillaries of the glomerulus the diameter of the capillaries in the glomerulus is much smaller then arteriolar one and thus as the blood enters the narrow capillaries the pressure rises and forces a plasma-like fluid to filter from the blood in the glomerulus into the bowman's capsule

Question 456

Describe the ultrafiltration in the renal capsule

Answer 456

the large molecules in the blood enter through fenestrations between the capillary cell but are unable to pass through the basement membrane (the "ultra-filter") which is the only barrier between the filtrate and the blood, allowing small solute molecules such as glucose and urea through but not large ones such as proteins

Question 457

State the function of podocytes

Answer 457

allowing the filtrate to pass rapidly and easily into the space of Bowmans capsule as there are gaps between the cells

Question 458

State with reason what functions as the "ultra-filter" in the renal capsule

Answer 458

the basement membrane is the only barrier between the filtrate and the blood, allowing small solute molecules (e.g. glucose and urea) through but not large ones (proteins)

Question 459

State the components of filtrate

Answer 459

water, glucose, amino acids, some salts and urea very much like blood plasma but there are far less protein and no blood cells present

Question 460

Define tubular reabsorption

Answer 460

reabsorption of useful substances from the filtrate within the renal tubules into the capillaries around the tubules

Question 461

State the path of tubular reabsorption

Answer 461

starts at proximal tubules Henle's loop distal tubule collecting duct

Question 462

State the percentage of the initial filtrate from the glomerulus that is reabsorbed by the nephron and returned to the blood in peritubal capillaries

Answer 462

99%

Question 463

State the adaptation of the proximal convoluted tubule cells to reabsorption

Answer 463

- large surface due to microvilli - numerous mitochondria - closeness of blood capillaries - intercellular and subcellular spaces increasing surface area for export

Question 464

State the function of loop of Henle

Answer 464

creation and maintaining high concentration of salts in the tissue fluid in the medulla of the kidney through the countercurrent mechanism

Question 465

State how the human kidney concentrated urine

Answer 465

through the two-solute model

Question 466

Define the countercurrent system

Answer 466

depends energy to actively transport NaCl from the filtrate in the upper part of the ascending limb of the loop of Henle to create concentration gradients, which maintains a high concentration in the interior of the kidney enabling the kidney to form concentrated urine

Question 467

Define the tubular secretion in distal convoluted tubule

Answer 467

involves substances which are secreted from the body and added to the tubular fluid such as K+, H+, NH4+, creatinine, some hormones and some drugs

Question 468

State the function of ADH in relation to kidneys

Answer 468

increases the permeability of the distal convoluted tube and collecting ducts to water and urea

Question 469

State the meaning of glucose in urine

Answer 469

common indicator of diabetes because it signalizes incomplete reabsorption

Question 470

State the meaning of proteins in urine

Answer 470

can indicate for example: PKU or hormonal conditions

Question 471

Define kidney failure

Answer 471

kidney tubules fail to filter enough blood and hence fail to clear toxins from the blood

Question 472

State two most popular methods of treatment of kidney failure

Answer 472

- hemodialysis - transplant

Question 473

Define the dialysis fluid

Answer 473

solution where the solutes are balanced to either cause or prevent diffusion with zero concentration of urea so that it diffuses out of the blood with glucose concentration equal of that to the blood so that no glucose leave the blood

Question 474

Define hemodialysis

Answer 474

blood circulates through the dialysis machine and is returned to the arm vein it passes along one side of a partially permeable membrane and dialysis fluid passes in the opposite direction on the other side of the membrane

Question 475

List the types of skeleton systems

Answer 475

external - exoskeleton internal - endoskeleton absent - hydrostatic

Question 476

State the function of bones

Answer 476

support and protection of the body parts anchorage for muscles

Question 477

State the brief function of joints

Answer 477

between bones permit movement

Question 478

State the function of tendons

Answer 478

attach muscles to bones at their points of anchorage

Question 479

Define the meaning that muscles are antagonistic and give example

Answer 479

when one contracts the other relaxes in lower arm the extension of it is caused by the contraction of the triceps muscle and relaxation of the biceps muscle

Question 480

Define with their function the ligaments

Answer 480

slightly elastic connective tissues connecting bone to bone and restricting the movement at joints and helping to prevent dislocation as they form a protective capsule around the joints

Question 481

State what does the strength of the resulting contraction of the muscle depends on

Answer 481

on how many muscle fibers the motor neuron controls

Question 482

Define a joint

Answer 482

junction between bones permitting controlled movement

Question 483

State the function of the synovial fluid

Answer 483

lubrication of the joint, nourishment of the cartilage and removal of any harmful detritus from worn bone and cartilage surfaces

Question 484

Define circumduction and state a type of joint permitting it

Answer 484

movement in all three planes a ball and socket joint such as a hip joint

Question 485

Define a hinge joint and give an example

Answer 485

one restricting movement to one plane example: a knee joint

Question 486

Compare and contrast the movement of the hip joint and the knee joint

Answer 486

Similarities: - both are synovial joints - both are involved in the movement of the leg Differences: HIP JOINT - ball and socket joint - capable of multi-axial movement and rotation: - flexion and extension - abduction and adduction - circumduction and rotation - Located between the pelvis and femur KNEE JOINT - hinge joint capable of angular movement in one direction: - flexion and extension - small amount of rotation may be possible - located between the femur and tibia

Question 487

Define a muscle fibre

Answer 487

group of modified muscles cells where many cells have joined end to end to form a single mass of cytoplasm with many nuclei

Question 488

Define a sarcomere

Answer 488

the basic unit of a muscle

Question 489

State what are muscle cells composed of

Answer 489

tubular myofibrils

Question 490

State what are myofibrils composed of

Answer 490

sarcomeres appearing as dark and light bands under the microscope

Question 491

State what are the thin and thick filaments of the muscles attached at

Answer 491

thin filaments - Z lines thick filaments - M lines

Question 492

State the positioning of the thick and thin filaments in a resting myofibril

Answer 492

partially overlapping

Question 493

Define the position of a sarcomere

Answer 493

portion of the myofibril between the two z-line

Question 494

State what are the thick and thin muscle filaments composed of

Answer 494

thin - actin protein thick - myosin protein

Question 495

State the reason for skeletal muscle shortening during contractions

Answer 495

the thick and thin filaments slide past one another

Question 496

Define the H zone in the sarcomere

Answer 496

are occupied by the thick filaments

Question 497

Define the I band (light) region in the sarcomere

Answer 497

region occupied by only thin (actin) filaments

Question 498

Define the H band (dark) region in the sarcomere

Answer 498

region occupied by both filaments - overlapping

Question 499

Define the Z band region in the sarcomere

Answer 499

extremities of a single sarcomere

Question 500

State a structural characteristic making the shortening of the muscle possible

Answer 500

myosin thick filaments have bulbous heads protruding from the filaments actin thin filaments have a complementary series of binding sites to which the bulbous heads fit

Question 501

State what is present at muscle fibers at least making the binding and contraction not possible

Answer 501

the actin binding sites covered with blocking molecules - tropomyosin and the troponin complex

Question 502

State the function of the calcium and regulatory proteins in muscle contractions

Answer 502

Ca2+ accumulates in the cytosol and binds to the troponin complex causing tropomyosin bound along the actin strands to shift position and expose the myosin-binding sites on the thin filament thus if the Ca2+ concentration rise in the cytisik the muscle fibers will contract

Question 503

State the effect of the motor neuron sending a signal to the muscle to contract that makes the muscle contract

Answer 503

causes a release of the Ca2+ ions by the sarcoplasmic reticulum interaction of calcium with troponin triggers the removal of the blocking tropomyosin and exposes the binding sites

Question 504

Label the neuron cell

Answer 504

- dendrites - nucleus - cell body (soma) - node of Ranvier - axon terminals - myelin sheath - Schwann cell

Question 505

label the urinary system

Answer 505

- thorax - renal vein - renal artery - vena cava - diaphragm - kidney (attached to dorsal wall) - ureter - dorsal aorta - bladder - urethra - sphincter muscle under voluntary control

Question 506

label the kidney

Answer 506

- nephrons - fibrous capsule - collecting duct - renal artery - pelvis - expanded origin of ureter - cortex - medulla - ureter

Question 507

Label the structure of a nephron

Answer 507

- afferent arteriole - Bowmans capsule - glomerulus - efferent arteriole - proximal convoluted tubule (PCT) - renal cortex - renal medulla - descending limb of Henle - loop of Henle - ascending limb of Henle - vasa recta - distal convoluted tubule (DCT) - collecting duct

Question 508

Label the structure of an elbow joint

Answer 508

- humerus - radius - ulna - cartilage - tendon of biceps - capsule of collagen fibres surrounds the joint - tendon of triceps - synovial membrane - synovial fluid

Question 509

Label the structure of an hip joint

Answer 509

- joint capsule - femur - pelvic girdle - synovial membrane - synovial fluid - pad of fat - ligament - head of femur - acetabulum - cartilage

Question 510

Label the structure of a muscle

Answer 510

- nucleus - mitochondrion - sarcoplasm - sarcolemma - z line - sarcoplasmic reticulum - thin actin filament - thick myosin filament - myosin head - sarcomere