BIOL 224 FINAL Flashcards
(129 cards)
1
Q
What is osmoregulation?
A
The process of maintaining salt and water balance across membranes in the body
2
Q
What is an electrolyte?
A
A compound that dissociates into ions when dissolved in water, makes up part of the fluids inside an surrounding cells
3
Q
What is osmosis?
A
The spontaneous movement of water through a selectively permeable membrane from low solute concentrations to high solute concentrations, works via entropy
4
Q
Why is osmoregulation important in animals? (2)
A
Salt and water concentrations in the cells provide an optimal environment for proteins and enzymes to function effectively
If ionic/osmotic/pH conditions in the cell are not ideal then physiological processes will be disrupted
5
Q
How does water cross the plasma membrane?
A
Aquaporins
6
Q
What is tonicity?
A
Measure of effective osmotic gradient, only influenced by solutes that cannot cross the membrane (hyper/ hypotonic)
7
Q
What are the two kinds of transport in epithelial cells?
A
Paracellular transport –> Movement between cells
–> Leaky vs tight
Transcellular transport –> movement across cell membranes
8
Q
What are the three homeostatic processes?
A
Osmotic regulation
Ionic regulation
Volume regulation
9
Q
What is an osmoregualtor?
A
Osmotic pressure of body fluids is homeostatically regulated and usually different from the external environment
Energetically expensive
terrestrial animals, freshwater fish, some marine fish
10
Q
What is an osmoconformer?
A
Maintains an internal environment osmnoticaoly equal to their external environment
mainly found in oceans where ~1000mOsm
High degree of cellular osmotic tolerance
Less energetically expensive
Marine invertebrates, some insects, sharks
11
Q
Describe the differences in osmoregulation between a marine and freshwater fish
A
In freshwater fish, –> inside of the fish has more solute = water moves into fish, removes mainly water in dilute urine
In marine fish, –> inside of the fish has less solute than water = water moves out of fish, removes mainly salt and little water through gills and scant urine
12
Q
What is an osmolyte?
A
A low molecular weight compound that influences the properties of biological fluids, can also interact with cell constituents and influence protein folding
ex) amino acids and sugars
ex) TMAO –> natural osmolyte that acts as an osmoprotectant
13
Q
What are the two kinds of osmoconformers?
A
Euryhaline –> adapted to a wide range of osmotic changes
common to species in intertidal zones, salmon
Stenohaline –> can only live in small ranges of salinity
most freshwater fish cannot survive in a marine environment and vice versa
14
Q
Are sharks osmoconformers or osmoregualtors? Explain
A
Sharks are osmoconformers, meaning they are isosmotic to their environment, but the makeup of internal ion concentration is not the same
Sharks use urea as an osmolyte to prevent water loss in the marine environment, keeping salts inside, too much can be bad so this is countered by TMAO
Sharks have slightly higher solute concentration than seawater meaning they do not need to drink water like other marine fish –> can use far less energy to osmoregulate
15
Q
What is the functional unit of the kidney?
A
The nephron
Responsible for the formation of urine
16
Q
What are the four basic nephron processes?
A
Glomerular filtration –> forming of the primary urine
Tubular reabsorption –> of substances that are needed by the body
Tubular secretion –> of substances to be eliminated
Excretion –> resulting in urine
17
Q
What does the glomerulus do and where is it located?
A
Bundle of capillaries situated between two resistance vessels, contained within the bowmans capsule
Glomerular filtration is the first step in urine formation
18
Q
Explain glomerular filtration
A
First step in urine formation –> separates plasma from the blood
Driven by blood hydrostatic pressure
Contains small plasma solutes and water
Contains no other cells or proteins
99% of filtrate is reabsorbed
19
Q
Give a broad overview of the formation of urine
A
Glomerulus, proximal convoluted tubule (PCT), loop pf Henle, distal convoluted tubule (DCT) and collecting duct (CD)
20
Q
Describe tubular exchange in the PCT
A
all tubular exchange with blood is done by a single layer of renal epithelial cells
–>NaKATPase is the main driving force in PCT providing energy for:
—> Cotransport of AA and glucose
—> countertransport of H
—> other molecules
21
Q
What is the renal threshold and what is the transport maximum
A
The renal threshold is when glucose transporters are fully saturated and glucose becomes lost in urine
The transport maximum is when all carrier pumps and proteins are occupied
22
Q
Describe reabsorption and secretion in the PCT
A
Reabsorption –> 65% of filtered water, same wth Na, 100% of glucose and AA
Secretion –> Urea, uric acid, H+, NH4+
23
Q
What is the function of the loop of Henle
A
The Loop of Henle is the U-shaped portion of the tubule divided into three main
segments. Recovers water and sodium chloride from urine and allows production of
urine that is far more concentrated than blood.
*The liquid entering the loop of Henle is the solution of salt, urea, and other substances not reabsorbed by the PCT.
*The thin descending limb, is permeable to water.
*The liquid reaching the bend of the loop is much richer in salt and urea than the blood plasma is.
*The thin ascending limb receives lower volume of fluid. Is the diluting segment of the nephron. –> Impermeable to water but permeable to ions:
*Ion concentration becomes more and more hypotonic from the bottom to the top.
*The loop of Henle establishes an osmotic gradient in the medulla via the use of urea, reabsorbs another20% of water
24
Q
Explain what happens when fluid reaches the DCT?
A
Fluid reaching the DCT is about 20% of the original filtered volume
*This fluid is hypotonic relative to plasma
*~7.5% of the filtered Na+ is reabsorbed in DCT & connecting tubule
*DCT is not usually permeable to water, but later nephron segments are
25
Describe optional and obligatory reabsorption in the DCT and CD
Aldosterone increase
-->*Expression of luminal Na⁺ channels, and
-->*Number of Na⁺/K⁺-ATPase pumps
--->*Stimulate Na⁺ reabsorption and K⁺ excretion;
ADH control expression of aquaporins
-->*Physical pathway for water to pass through cells;
Both hormones control the quantity of water that is reabsorbed;
Atrial natriuretic peptide;
-->*A hormone secreted by the atria of the heart
-->*Inhibit Na+reabsorption.
26
How is mineral balance regulated in the DCT and CD?
Hypothalamic osmoreceptors detect increases
in blood osmolarity(Sp.) and respond with:
Increase ADH secretion from the posterior pituitary gland.
-->*Acts on the kidney to reabsorb water from the forming urine.
Inhibit aldosterone secretion
-->*Causes elimination of Na+
Increases ANP secreted from the atria of the heart.
-->*Decreases Na+ reabsorption.
these changes all target the principle cells of the DCT
27
Explain Hormonally controlled reabsorption of Ca2+ in the DCT & CT
Obligatory reabsorption Ca2+ occurs mainly in the PCT.
But parathyroid hormone (PTH) secreted by the parathyroid glands control Ca2+ reabsorption.
Target the principal cells of the ascending loop of Henle DCT and CD.
28
What are the nitrogen compounds that animals must excrete?
Ammonia (NH3) --> very toxic
Urea
Uric acid
a combo
29
What are the three methods to excreting ammonia (NH3)?
Ammonotely --> Nh3 can be safely transported and excreted from the body in diluted solutions, animals with plenty of water excrete ammonia as their primary waste
Some get rid of it through diffusion through respiratory surfaces (tadpoles)
energetically expensive
Ureotely --> other animals detoxify ammonia by converting it to urea
mammals, most amphibians, some terrestrial invertebrates
requires much less water
--> in ruminants, after synthesis in the liver, urea enters the rumen via saliva
Uricotelic --> water is conserved even more by the formation of uric acid
energetically more expensive, but less toxic b/c very insoluble
used by many reptiles and birds --> ostrich is the exception
30
What is the role of the kidney in acid base regulation?
Intercalated cells in the DCT & collecting ducts participate controlling pH in the internal media.
α-intercalated cells secrete protons via an apical K+/H-ATPase and reabsorb bicarbonate by a Cl/HCO3 exchanger, located in the basolateral plasma membrane.
b-intercalated cells secrete bicarbonate by an apical Cl/HCO3exchanger
31
What is both the biochemical and physiological definition of respiration?
Biochemical --. metabolic process by which an organism obtains energy by oxidizing nutrients an releasing waste products
Physiological definition --> movement of O2 form the outside environment to cells within tissues and removal of CO2 to the environment
32
How does O2 get from the air to the mitochondria? (4)
Ventilation
Diffusion of O2 into blood
Perfusion --> passage of fluid thru system to organ or tissue
Diffusion --> of O2 from tissues to mitochondria
33
What is external respiration
gas exchange through thin membrane, only works on very small animals, diffusion has to follow ficks law which dictates maximum rate of diffusion and can be used to compare to body size
34
Why did circulation evolve?
To bypass the limits imposed by diffusion --> reduces distance between tissues and PP O2/CO2
35
Explain the benefits of respiration in an aquatic environment
O2 more soluble in cold water than warm
Respiratory surface can be kept wet
Rate of diffusion is slower
Ventilation in a one way direction --> gills --> water moves one way over gills while blood goes the other --> maximizes P and O2 diffuses as a very high rate
CO2 is 20 times as soluble in water meaning excretion can be achieved by ventilation required to get O2
36
I think i know the hemoglobin stuffs, its allosteric, cooperative, high o2 affinity etc
yea
37
What does carbonic anhydrase do?
catalyze rapid interconversion of Co2 and H2O to bicarbonate and H+
Helps get CO2 out
38
What are gills?
Respiratory organs with extensions of the body respiratory surfaces
Provides a high surface area used by aquatic organisms to efficiently extract dissolved O2 from water and to excrete CO2
39
What are the two kinds of gills?
External gills --> extend out from body, no protective coverings, use tentacle like structures --> small molluscs
Internal gills --> protected by body chambers, currents of water are directed over the gill
40
What are the two kinds of ventilation in fish?
Double pumping mechanism --> bony fish, creates pressure gradient by opening and closing of mouth
Ram ventilation --> pelagic fish like some sharks and mackerl, breathe by moving forward
41
What are gill lamellae?
Thin plate-like structures with a capillary blood network
--> increased the surface area of contact with the environment to maximize gass exchange
--> primarily occurs along the length of the secondary lamellae
--> the tissue is only one cell layer thick
42
Why are countercurrent gas exchangers so efficient?
PO2 in the gills is higher than P02 in blood
43
Explain gas exchange in large and small insects
In small insects --> simple diffusion through tracheoles
In large insects --> ise ventilation via the opening and closing of spiracles
In insects co2 is taken up by HCO3 resulting in negative pressure that opens spiracles
44
Explain how birds breathe via cross current exchange (6)
The air sacs, which collectively contain several times as much air as the lungs, are not respiratory surfaces.
*Bird lungs are rigid and do not expand or contract.
*The air sacs do,
Air flow only in one direction through the lungs
*Rather than in and out, as in other vertebrates.
Two cycles of inhalation and exhalation are needed
Air always flows through the lung from back to front
*through an array of fine, parallel tubes that are surrounded by a capillary network.
Blood flows in a direction across that of the air-flow
*Crosscurrent exchange.
*Bird lungs extract more O2from the air than the lungs of mammals do, but less than with the countercurrent exchange system seen in fish.
PO2 of blood leaving the breathing organ is higher than exhaled medium
45
How do birds fly at high altitudes?
Reduce the O2 demand by lowering metabolism
Decrease temperature in lungs --> increasing O2 loading
46
Describe the branching that occurs in the mammalian lung
Trachea forms two primary bronchi
Bronchi branch into bronchioles
Bronchioles branch and eventually become alveoli ~300mil total
47
Explain how gas exchange in the mammalian lung occurs by ventilation and perfusion
ventilation refers to the movement of air in and out of the lungs
negative pressure mechanism --> air is exhaled passively, diaphragm plays role
air is forced into the lungs via positive pressure by muscle contractions
perfusion is the circulation of blood in the pulmonary capilleries
tidal ventilation, uniform pool, ppO2 is lower in blood than fresh air meaning it diffuses
48
How do we control our breathing?
Peripheral chemoreceptors
Monitor PPCO2, pH, and PO2 (second response)
49
How do amphibians breathe?
Via positive pressure breathing, effectively swallow the air
little folding in lungs and high efficiency because CO2 is easily lost via skin
50
Describe circulation in protostomes such as sponges and cnidarians
have no specialized circulatory systems
Products of digestion exchange via diffusion
Sponges use water to aid digestion
Cnidarians have a gastrovascular cavity attached to their mouth
51
Describe open circulatory systems and where they are found
Found in many invertebrates
Flows hemolymph through vessels, empties into open body cavity, no arteries or veins
Hc is suspended in hemolymph and not attached to blood cells
some insects have accessory hearts for each wing and leg which help pump as a part of the digestive process
52
Describe combined circulatory systems and where they are found
Found in annelids (worms)
combines open and closed systems
Blood circulated through a closed network of blood vessels, pumped by self contraction
53
Describe closed circulatory systems and where they are found 3 types
Found in all vertebrates
Network of blood vessels adn capilleries, separated from interstitial fluids
3 types
--> single circuit in fish
--> parallel circuit in amphibians
--> double circuit in mammals and birds (and crocodiles) (systemic and pulmonary circuits)
54
What are arteries?
Blood vessels that carry blood away from the heart
arterioles --> smallbranches of arteries that deliver blood to capilleries
55
What are capilleries?
Exchange material with interstitial fluid
Single cell layer
near body cells
most numerous in body --> 10bil
highly regulated through autonomic NS
56
What are veins?
Blood vessels that return blood to heart
aided by limb muscle pumps and valves --> prevents backflow
thinner than arteries
57
What are portal circulatory systems? (3)
Systems in which veins or arteries start and end in capilleries
Glomerular --> filters blood
Hepatic --> delivers nutrient rich blood to the liver
Hypothalamus-pituitary --> delivers hypothalamic hormones to anterior pituitary gland
58
Describe the heart contraction cycle
atria then ventricles
alternating periods of systole (contraction) and diastole (relaxation)
59
What are heartbeat sounds from?
The first sound is the atrioventricular valves closing
The second sound is the pulmonary and semilunar valves closing
60
Describe the properties of the myogenic cardiac muscle (6)
Myocardial cells are striated non-voluntary;
Electrophysiologic properties:
Automaticity:
-->*Spontaneously generate an electrical impulse;
Excitability:
-->*Respond to an electrical impulse.
Conductivity:
-->*Transmission of the electrical impulse to another cardiac cell.
Contractility:
-->*Contract after an electrical impulse;
Rhythmicity:
-->*Send electrical impulses in a regularly and evenly paced manner; and
Refractoriness:
-->*Inability to respond to another electrical impulse.
61
What are the two kinds of cardiac cells in the myocardium?
Pacemakers:
*Large number of gap junctions.
*Spontaneously create and discharge an electrical signal that define cardiac rhythm;
Myocardial:
*Respond to the electrical stimulus from the pacemaker causing contraction.
62
Circulatory fluids in cells --> what is the hematocrit?
Hematocrit is the fluids that make up blood
Volume % of RBC in blood --> 42% in females 45% in males
rest is plasma
will be higher for higher aerobic emands, seals that hold breath have higher %, same with animals at high altitudes
Icefish have very low
63
What are the three broad kinds of blood cells?
Erythrocytes --> RBC
Leukocytes; --> WBC
*Nucleated white cells of the immune system;
*Found throughout the body, including the blood and lymphatic system;
*Protect against infectious diseases;
*Divided into the five main types:
-->*Neutrophils;
----->*phagocytic,
----->*70%
----->*Short life
-->*Eosinophils (acidophilus)
----->*Respond to parasitic infections
-->*Basophils,
----->*Heparin
----->*Histamine
----->*Allergic reactions
-->*Lymphocytes,
----->*B cells, T cells, and natural killer (NK) cells
-->*Monocytes;
----->*Phagocytic
----->*Larger life.
*Platelets
*Also termed thrombocytes (thromb- + -cyte, "blood clot cell”);
*Anucleate cells found only in mammals
*Along with the coagulation factors stop bleeding by clumping and clotting blood vessel injuries;
64
What are the functions of plasma proteins in blood?
Colloid osmotic pressure
Limit passage through capilliary pores
Establish osmotic gradient between plasma and interstitial fluid
Partially responsible for buffering capacity
Fibrinogen
Key factor in the blood-clotting;
*Converted into fibrin;
Albumins - the most abundant, transport:*Bilirubin, bile salts, and fatty acids; and
*The major contributor to colloid osmotic pressure;
Globulins - a, b, and g:
*Transporters. Specific a- and b-globulins bind and transport
*Clotting agents - factors involved in blood clotting
*Regulators - Inactive proteins;
*Immune effectors;
-->*Antibodies are g-globulins involved in immune defense mechanisms in vertebrates.
65
Four major lipoproteins in vertebrates
Chylomicrons --> transports triglycerides
High density --> most protein
Low density --> less protein
very low density --> least protein, most lipid, triglycerides
66
Broadly describe the lymphatic system
open system of fluids circulating
part of the immune and circulatory system
lymphatic vessels carry lymph back to heart for re circulation
Lymphoid organs include
Lymph nodes --> high lymphocyte concentration
spleen
thymus
tonsils
accessory return route for blood, about 3/20 litres filtered by it
Absorbs and transports fats from the digestive system via lacteals, to be processed by liver
67
Explain what lymph is and how it is formed
Fluid from circulating blood leaks into the tissues of the body by capillary action, carrying nutrients to the cells
Collecting waste products, bacteria, and damaged cells, and
Drains as lymph into lymphatic vessels.
Lymph pass through lymph nodes that filter out unwanted materials, and
Pass into lymph ducts that moves by muscle contractions.
The right lymphatic duct empty into the subclavian veins to return to the blood circulation.
68
What does a lymph node do?
800 in body
filters lymph that passes on its way to the blood
traps foreign particles and abnormal cells
69
How is metabolism and metabolic rate regulated?
Regulated by the CNS and various hormones in mammals:
*Motor NS increases skeletal muscle activity.
*Autonomic NS switches between PNS and SNS.
Key anabolic hormones:
*Growth hormone
*Insulin, and
*Testosterone
Key catabolic hormones.
*Epinephrine
*T3 directly stimulates cellular ATP & heat production
*Cortisol,
*Leptin, produced by adipose cells
*Regulate energy balance by inhibiting hunger,
*Diminishes fat storage in adipocytes.
70
explain countercurrent exchange in paws
Warm arteries heatup the cooler veins;
*Minimize heat loss by the extremity in contact with the ground;
*Temperature in the paw stays balanced;
*It also prevents the body core from being cooled by heat loss at the extremities;
*Also found in the feet of birds such as ducks and penguins.
71
Explain the 6 metabolically regulated pathways (esis/ ysis)
Glycogenesis: glycogen synthesis;
*Stimulated during rest periods in the liver by insulinin response to high glucose levels.
Glycogenolysis: breakdown of glycogen.
*Takes place in muscle and liver tissues in response to a variety of hormonal and neural signals;
Gluconeogenesis: synthesis of glucose from non-sugar precursors.
*Glucose is the only energy source used by the brain, testes, erythrocytes, and kidney medulla.
*Stimulated by catabolic hormones.
Glycolysis: the metabolic pathway that converts glucose into pyruvate.
Lipolysis: hydrolysis of triglycerides into glycerol and free fatty acids;
*Stimulated by epinephrine, norepinephrine, ghrelin, growth hormone, testosterone, and cortisol.
Lipogenesis: process by which acetyl-CoA, an intermediate in metabolism of glucose, is converted
into fatty acids;
*Energy can be efficiently stored in the form of fats;
*Stimulated by insulin when blood sugar levels rise,
*Insulin promote absorption and storage of sugars and synthesis of lipids.
72
What are the two essential linoleic acids in humans
Omega 3 --> fatty acid in seeds and oils
Omega 6 --. fatty acid present in vegetable oils
73
What are the four kinds of feeders?
Fluid feeders
Suspension feeders
Deposit feeders
Bulk feeders
74
What are the 5 stages of digestion in the GI tract?
Mechanical processing --> chewing and grinding of food
Secretion of enzymes and other digestive acids --> into Gi tract
Enzymatic hydrolysis --> of food molecules into molecular units
Absorption--> of molecular units across cell membranes
Elimination --> of undigested matter
75
Explain chemical breakdown in the digestive system
Bonds are broken by enzymatic hydrolysis
--> adding H and Oh from water
Driven by molecule specific enzymes (lipases = lipids)
Is intracellular in sponges and cnidarians
is extracellular everywhere else --> herbivores ferment in the digestive tact
76
What is the GI tract?
Tube with 2 openings, has compartmentalization with different functions
Earthworms have a crop and gizzard --> stores stones
77
What are the three parts of a grasshoppers digestive system?
Foregut, midgut, hindgut
78
What is a monogastric organism?
some herbivores, carnivores and omnivores
long digestive tracts, takes a long time to digest plant material especially
simple single chambered stomachs
large caecum which helps break down cellulose (herbivores)
carnivores have a larger stomach and produce more powerful gastric enzymes
79
what is a polygastric organism?
some herbivores
four chambered complex in ruminants
three chambered in camels
two in kangaroos
In ruminants, 3 pre gastric chambers --> rumen, reticulum, omasum
One gastric chamber (true stomach) --> abomasum
80
What is the order that food moves through a humans GI tract/
Gut layers, swallow, stomach, small and large intestine, rectum, anus
81
What is mastication
mechanical processing of food by the mouth,
facilitates swallowing and increase food surface area for enzymes to act on
increases digestive secretions
82
Describe mastication in herbivores
ruminants have no teeth in upper maxillary --> only chew food briefly
grind food into small pieces called a bolus
regurgitates bolus back to mouth, for more salivation
83
What are the three major salivary glands and what are its 6 functions
Parotid, Submandibular, Sublingual,
Protection:
*Mucins lubricate and protect both the soft and hard tissues of the oral cavity.
Buffering and cleaning:*Protection from dental wearing and caries.
*Saliva proteins inhibit demineralization and promote remineralization by attracting calcium & phosphate ions.
Antimicrobial action:*Lactoferrin in saliva binds iron preventing microbial growth
*Antimicrobial peptides inhibit the growth of yeast and bacterial
*Immunoglobulin A aggregate oral bacteria preventing dental plaque.
Tissue repair:*Encourage soft-tissue repair by decreasing clotting time and increasing wound contraction.
Digestion:
*Amylase hydrolyses starch into glucose, maltose, and dextrin.
Taste:
Saliva acts as a solvent in which solid particles can dissolve and enter the taste buds through oral mucosa located on the tongue.
84
how does digestion work in the stomach? and what is gastric motility?
via gastrin, a peptide hormone
stimulates secretion of HCl and gastric motility
Motility
coordinated contractions of muscles mix contents and move it to the duodenum
produces chyme --> partially digested food mix resulting from chemical breakdown of contents
85
What are the three parts of the small intestine?
The duodenumreceives and neutralize the acidic gastric chyme.
*Enteroendocrine organ that produces two hormones:
*Cholecystokinin (CCK):
*Secretin:
*Digestive enzymes break down proteins
*Bile emulsifies fats into micelles.
The jejunum absorbs:
*Nutrient particles digested in the duodenum.
*Sugars, amino acids, and fatty acids.
The ileum absorbs:
*Vitamins B12 and K, produced by anaerobic bacteria,
*Bile acids, and
*Products not absorbed by the jejunum
since it has a pH of 7, gastric enzymes don't work and pancreatic enzymes do the rest
86
What are the three brush border enzymes in the small intestine?
Maltase
Lactase
Sucrase
87
What does the liver and gallbladder do?
Only found in vertebrates *Performs ~ 500 essential biological functions.
*Metabolic: --> *Regulation of glycogen storage.
*Detoxification.
*Synthesis of proteins and hormones.
*Decomposition of red blood cells.
*As an accessory digestive organ produces bile.
*The gallbladder. --> *Small pouch that sits just under the liver.
*Stores bile produced by the liver.
88
What does the large intestine do?
Sphincter at the junction between the small and large intestines.
*Controls the passage of material and prevents backward movements.
Several distinct regions:
*At the junction with the small intestine,
forms a blind pouch: --> *The cecum:
--> A fingerlike sac, the appendix, extends from the cecum.
--> cecum merges with colon, forming rectum
89
Explain the function of the abomasum
ruminants true stomach
starts the process of typical vertebrate digestion, absorbs lots of water
urea recycled via the salivary glands goes back to the rumen and is used by microbes for protein synthesis
90
Discuss fermentation in ruminants
digestion is a long process takes 55 hours
O2 levels are too low for mitochondrial reactions, uses anaerobic microbes to ferment and digest --> acetyl coa
converted into volatile fatty acids --> absorbed and metabolized
results in production of large amounts of smelly gasses
have very alkaline saliva --> salivary bicarbonate to neutralize pH of rumen fluid
91
What are the three main components for communication in an animals body?
Chemical signalling
A system of signal reception
--> ion channels
--> cell receptors
Cellular response
--> opening ion channels
--> internal response pathways triggered when cell receives a signal
92
What is the endocrine system?
A system of communication through chemical signals secreted by endocrine glands
--> organs of epithelial and neural origin that secrete hormones
93
What are hormones? and what are the broad types of vertebrate hormones?
signalling molecules synthesized and secreted by special cells that are released into the extracellular space and exert specific biochemical actions on target cells
termed ligands when they bind to receptors
Peptides/ glycoproteins
Amines --> thyroid hormones, epinephrine
steroids
94
What are hormones?
Signalling molecules synthesized and secreted by special cells that are released into the extracellular space and exert specific biochemical actions on target cells
termed ligands when they bind to receptors
95
What are pheromones?
Water or air soluble molecules that are secreted to the environment and received by individuals of the same species
96
What are the three broad divisions of an animals body and fluids?
Intracellular, extracellular and intravascular
97
How are the nervous system and endocrine system related?
The pituitary gland or hypophysis is located on the base of the hypothalamus, a part of the brain
98
What is prolactin?
Hormone that stimulates the mammary glands --> produces milk
99
What are the gonadotropins?
Folicle-stimulating hormone and luteinizing hormone --> stimulates gametes, stimulates follicles, triggers ovulation
100
What is TSH
Thyroid stimulating hormone --> increases rates of metabolism
101
What is ACTH?
Adrenocorticotropic hormone --> helps regulate fluid balance, helps cope with stress situations
102
What is GH?
Growth hormone --> promotes growth
103
What is MSH?
Melanocyte stimulating hormone --> promotes skin daarkening
104
What are endorphins?
Produces by the pituitary gland --> affects pain pathways of the PNS, inhibits pain reception
105
What is ADH? Or vasopressin
Antidiuretic hormone --> increases permeability in the nephrons in kidneys
Increases aquaporin expression
106
What is oxytocin?
Hormone produced by the pituitary gland that affects uterus and mammary glands, stimulating contraction and milk production
107
What are some intracellular receptors?
Includes the nuclear transcription factor
They bind thyroid hormones and steroid hormones such as sex steroids
108
What are the two kinds of signalling receptors?
surface membrane receptors and intracellular receptors
109
What are the regulators of GH, when is GH secreted the most?
Stimulated by --> hunger and exercise, ghrelin, GHSH
Inhibited by --> GHIH, negative feedback loops, hyperglycemia
Most secreted while sleeping
110
What is the primary energy storage substance and where is it used
Glycogen as it is insoluble
Glycogen rapidly broken down to glucose in gluconeogenesis in liver and muscles
Additionally use triglycerides in non glucose dependant tissues, broken-down into fatty acids, glycerol molecule can be converted to glucose via gluconeogensis
111
Fully explain the endocrine pancreas and what it does
Is a complex endocrine and exocrine organ
Islets of Langerhans are scattered throughout
-->a cells produce glucagon
-->b cells produce insulin
Insulin is released when blood glucose is high
Glucagon is released when blood glucose is low
Other, Delta cells produce somatostatin, decreases secretion of both and itself
112
What is the difference between the two types of diabetes?
Type 1 --> pancreas fails to produce insulin
Type 2 --> cells fail to respond to insulin --> body weight
113
What are the four main catabolic hormones, where do they come from and what do they do?
Glucagon --> from pancreas, increases glucose in bloodstream by breaking down stores gylogen in glycogenlysis or converting sources to glucose in gluconeogenesis
Epinephrine and Norepinephrine --> Adrenal medulla, preps body for fight or flight response, increases blood glucose
Glucocorticoids (cortisol and corticosterone) --> adrenal cortex, promotes gluconeogenesis in the liver in times of stress
T3 and T4 --> thyroid gland --> affects every tissue, increases glycemia
114
What is aldosterone?
A mineralocorticoid secreted by adrenal cortex
Regulates balance of salts and water
Acts on kidneys causing active reabsorption of Na in DCT, and active sectretion of K and H via ATPases
This increases blood pressure and volume
Since sodium is attracted to water this increases osmotic pressure as well, which drives filtration in the glomerulus
Regulated by angiotensin which increases and K
115
How is blood osmolarity regulated?
Aldosterone increases Na retention, ANP generates Na loss, work against each other
Increasing ADH secretion can also help reabsorb water lost from aldosterone
116
What is PTH and what does it affect / do? (last part is exam q)
Parathyroid hormone
Increases Ca2+ concentration in blood through effects on bones, kidneys and small intestine
Stimulates production of activated Vit D --> increasing Ca abruption in intestines
Excretes phosphate and absorbs Ca in kidneys
Stimulates osteoclasts to release Ca, although this is an indirect affect, inhibits calcium deposition in bones
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What does calcitonin do?
opposite affect in bones as PTH, keeps Ca in, reducing blood calcium
118
What are the three forms of asexual reproduction?
Budding, Fragmentation, Parthenogenesis (unfertilized eggs)
119
What is the difference between primary and secondary sex characteristics?
Primary characteristics are physical features directly required for reproduction (penis)
Secondary sex characteristics are sexually dimorphic features that are not part of the reproductive system by distinguish the sexes (adams apple)
120
What is puberty?
Period when body has reached sexual maturity and becomes capable of reproduction
Initiated by hormone signals from brain and gonads --> GNRH, gonadotropic releasing hormone
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What is gonadal function regulated by?
The pituitary gonadotropins
FSH and LH, same family as human chorionic gonadotropin
The pituitary gonadotropins are regulated by gonadotropin releasing hormone (GnRH)
122
What are two different specialized cells found in the testes?
Sertoli cells --> produce and nourish sperm cells
Leydig cells --> secrete testosterone
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What is the corpus Luteum?
Temporary endocrine structure in ovaries following restricting of ovarian follicle after ovulation --> produces lots of progesterone
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What are the four kinds of ovarian follicles?
Primordial follicles --> precursor of female gametes, 200k left at puberty
Primary follicles --> limited # of primordial become primary
Secondary follicles --> even more developed
Tertiary follicles --> very developed, contains oovyte to be released
125
Explain the feedback loops that occur in the ovarian cycle
In the follicular phase, estradiol uses negative feedback to limit FSH and LH
When follicle is ready, estradiol jumps, causing positive feedback on FSH and LH, they increase
Corpeus luteum develops and releases progesterone inhibiting FSH and LH to prep uterus for embryo
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What is the acrosome?
In the head of sperm, is an organelle from golgi apparatus
breaks down outer membrane of ovum
allows haploid nucleus of sperm and egg to join
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Describe in detail the three steps to fetilization
Acrosome reaction --> breaks down outer membrane of ovum
Cortical reaction --> triggers liberation of the intracellular messenger IP3 from membrane
--> IP3 binds to receptors on ER, opens Ca2+ channels dramatically increasing it
--> this depolarizes egg membrane (first barrier to polysmery)
--> Hardens outer membrane of ovum, second barrier
--> activates molecular signals that initiate first cell cycle of embryo
Sperm head fusion --> sperm fuses with egg resulting in zygote
128
What are the effects of hCG during pregnancy?
hCG is produced by placenta after implantation to support corpus luteum to continue producing progesterone --> this is what is detected in pregnancy tests
spikes from week 4-20 before estrogen and progesterone take over
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What is ANP
Stimulates Na loss, decreases Na reabsorbtion
