sem 2 exam Flashcards
how do scientists investigate
literature review: reviewing past discoveries
observation: information gathered using senses or instruments that enhance senses
classifying: placing things in groups based on similarities of characteristics
experimentation: designed to support/disprove a hypothesis
steps to scientific method
- recognise problem and make question
- collect information regarding problem
- make hypothesis
- Test hypothesis using experiment
- collect data
- draw conclusion on whether hypothesis was proved or not
if disproved, make a new hypothesis
ethical considerations
- voluntary participation: no pressure
- informed consent: fully informed about procedure (risk)
- no risk of harm: risk minimised
- confidentiality: participant identity not revealed
- anonymity: stronger than confidentiality, participants anonymous even to researcher
objectivity
scientists shouldn’t let thoughts/feelings affect interpretation or recording of results
cell membrane
brief
surrounds cell, forms outer boundary of cell
separates from neighbouring cells and external environment
made of double layer of lipids (phospholipid bilayer)
determines what gets in and out
cytoplasm
thick fluid within cell membrane
all structures suspended in it
cytosol is liquid part (75-90% water with complex dissolves substances) proteins and fat don’t dissolve so they are suspended in cytosol
nucleus
contains genetic material (DNA)
separated from cytoplasm by nuclear membrane, membrane has has nuclear pores so large molecules can pass
double membrane separated by space
nucleolus composed of RNA (manufacture of proteins)
DNA and nucleolus suspended in jelly-like nucleoplasm
largest organelle
Golgi body
flattened membrane bags stacked on top of each other
modify proteins and package them in vesicles for secretions from the cell
vesicles pinched off from edges of membranes
proteins produced at ribosome pass through channels in ER to golgi body
edges of Golgi body membrane small bubbles of liquid containing protiens are formed. bubbles surrounded by membrane (called vesicles)
ribosomes
small spherical organelles
where amino acids join to make proteins
can be free in cytoplasm or attached to membranes within cell (rough ER)
centrioles
pair of cylindrical structures usually located near the nucleus
important for reproduction of the cell
lysosomes
small spheres bounded by membrane, that contain digestive enzymes able to break down proteins, lipids, nucleic acids, some carbohydrates and large molecules
break down materials that are taken into the cell or breakdown worn out organelles
made by Golgi body
particles/liquids enter cell as vesicles formed in cytoplasm: then lysosomes join with the vesicles and digestive enzymes that contain breakdown the material inside the vesicle. they can digest old organelles in the same way.
mitochondria
spherical elongated structure
double membrane
1. outer smooth surrounding mitochondrion
2. inner folded toward centre of mitochondrion
release energy for cell through cellular respiration
folded membrane increases surface area on which chemical reactions can occur
Endoplasmic reticulum
pairs of parallel membranes extending through cytoplasm
connects cell membrane and nuclear membrane
surface on which chemical reactions can occur
storage and transport
rough have ribosome attached
smooth: no ribosomes, lipid synthesis
cytoskeleton
framework of protein fibres that give a cell its shape and assists cell movement
microtubules: rods that keep organelles in place/move them around cell. not permanent (broken/built as needed)
microfilaments: move materials around cytoplasm/whole cell
inclusions
not part of cell structure
found in cytoplasm
cilia/flagella
on the surface of the cell. Tiny hairs called cilia, if it is longer and fewer it is called flagella
they move mucus and trapped particles (cilia in windpipe)
flagella in sperm cell helps it swim
why are cells small
there is a limit to how big a cell can be.
A small cell will have a larger surface area to volume ratio then a large cell.
cells have to be microscopic to function effectively.
A large cell could not support itself because it would not have enough surface to absorb the nutrients required, and remove the wastes produced by its large volume
homeostasis
The maintenance of a constant internal environment of cells despite fluctuations in external environment
body systems work together to ensure a constant body temperature, correct level of molecules or ions maintained, fluid levels and body are correct
cell membrane function
- it is a physical barrier: protect ourselves and separate cells cytoplasm from the extra cellular fluid. this is important because the composition of the cytoplasm and the extracellular fluid are very different
- regulates passage of materials: what enters and leaves, controls the movement of materials into and out of the cell. Achieves this through its semipermeable membrane
- sensitivity: protein receptors in membrane are sensitive to certain or particular molecules around it for example hormones. The cell membrane is the first part of the sale affected by any changes in the extracellular fluid
- support: inside part of membrane has microfilament’s attached, which is part of the cytoskeleton. there are also connections between the membranes of adjacent cells that give support to the whole tissue of which the cells are apart
cell membrane structure
membrane is the phospholipid bilayer (2 layers), The main building blocks are phospholipids.
phospholid= lipid molecules with phosphate group
1. hydrophilic head made of an alcohol and glycerol group
2. hydrophobic tail made of chains of fatty acids
3. glycerol backbone
phospholipids can move sideways and allow water and other nonpolar molecules to pass through into or out of the cell
proteins and other molecules are in bedded in the membrane, it is called the fluid mosaic model.
fluid= proteins/molecules are constantly changing positions
mosaic=composed of many different types of molecules
A variety of proteins and cholesterol molecules are embedded in the bilayer some past through the membrane others are only on the surface. Cholesterol makes the membrane more fluid.
membrane proteins
- channel proteins: form a central pole, allow small ions, water, and other small molecules to pass through by simple diffusion
- receptor proteins: receive information to provide a response (hormone, insulin)
- Carrier protein: are specific, allow certain materials to bind to it, For example only glucose, amino acids. allows facilitated diffusion for example glucose and active transport (specific membrane pumps)
- cell identity markers: identifies the sale as self to prevent attack by the bodies immune system. They have carbohydrate parts attached to it to help cells in recognising each other and certain molecules
diffusion
passive process from random movement
spreading out of particles til evenly distributed
*more collision in HC areas
moves from area of high concentration to low
some molecules move against because it is random
o2 and co2 diffuse through membrane
*alcohols and steroid (fat soluble molecules) diffuse through lipids in membrane
osmosis
diffusion of water across a differentially permeable membrane from areas of high concentration to low
increase concentration of solute, increased osmotic pressure
carrier proteins
specific: they will only buy to a particular molecule. for example the carrier that transports glucose can not transport any other molecules
saturated: once all the available carriers are occupied, any increase in the concentration of molecules to be transported cannot increase the rate of movement.
Regulated by hormones: they are important in coordinating the activities of carrier proteins
facilitated diffusion
diffusion with help, where molecules diffuse across cell membrane with assistance of carrier proteins. carrier protein changes shape and molecule is released on the other side of membrane
diffusion takes place from high concentration to low concentration does not require ATP for example amino acids or glucose
proteins bind to molecules
bring in glucose and AA
active transport
process of using ATP to pump molecules across membrane against the concentration gradient
they move from low concentration to high concentration
using active transport a cell can take in or pass out substances regardless of their concentration which is why energy is needed. For example membrane pumps sodium ions and potassium ions which are high in the nerve cells of the body
bring in glucose, certain ions, AA
endocytosis
process that brings materials into the cell
involves the cell absorbing large particles such as proteins or even whole organisms such as bacteria, viruses, from outside by engulfing them with the cell membrane to form a vesicle like a bubble with in the cytosol
brings in cholesterol, iron ions
The cell membrane folds around a particle until the particle is completely enclosed, the vesicles so formed then pinches off and suspended in the cells cytoplasm
exocytosis
release of molecules from the cell, things leaving the cell
contents of vesicle are emptied, vesicle formed inside cell then, membrane of vesicle fuses with the cell membrane and contents emptied into extracelluar fluid
empty secretions such as mucus or digestive juices
epithelial tissue
covering and lining tissue that protects
lines inside of organs
consist of cells very closely joined together
cells that vary in size in different tissues (thin&flat, column/cube shaped)
mouth lining, outside lung, outer layer of skin
connective tissue
supporting tissue that holds body parts together
made of widely spaced cells separated by noncellular material called matrix
eg: blood, bone, adipose (fat) tissue, ligaments (bone to bone), tendon (muscle to bone), cartilage
under skin there is loose connective tissue
matrix of blood is plasma
muscle tissue
contracting tissue that responds to stimulus
made of long, thin, muscle cells/fibres
responds to stimulus by contacting and relaxing
skeletal: (striated/voluntary) attached to bones
arms and legs
smooth: (non striated/involuntary) in walls of many organ
uterus, stomach, blood vessels
cardiac: branched and striated with intercalated discs/involuntary) contacts to pump blood around body
involuntary: something you can’t control
nervous tissue
carries message in form of electrical impulses around body
found in brain, spinal cord, nerves
composed of neurons (nerve cells) with long projections from the cell body
stimulation of a neuron causes messages of to be passed along projections throughout the body
metabolism
total of all chemical reactions/processes occurring in your body. maintains a balance between energy released and energy used
c:breaking down
large molecules broken down to smaller ones
energy released
cellular respiration
a: building up
small molecules built up to larger ones
energy required
enzymes
proteins that allow chemical reactions to take place at body temperature
enzymes work by reducing activation energy
enzymes are specific: enzyme and its substrate have a shape and structure that allow them to fit together. complementary
part of enzyme where molecule combines with substrate is the active site, when combined it is the enzyme-substrate complex
- enzymes can be denatured (lose shape) by heat and lose catalytic properties
- optimum temp is 37ºC and pH varies. over 45ºC enzymes are denatured
factors influencing enzymes:
- increasing concentration of enzyme can increase rate
- increasing substrate concentration will increase rate as more molecules contact enzymes
- products must be removed continuously
- has optimum temp
- has optimum ph
- some need cofactors/coenzymes to change active site shape for reaction
- enzyme inhibitors slow or stop enzyme activity. controls reactions
energy for cellular respiration
60% heat energy
40% for ATP
inorganic phosphate group joins ADP, ADP and phosphate have a weak bond with stored energy, removing phosphate group releases energy
ATP can transfer energy from cellular respiration to cell processes that use energy and ADP can be reused
Anaerobic respiration
glycolysis: breaks down one glucose molecule to make 2 two molecules of pyruvate (pyruc=vic acid C3H4O3)
also makes 2 molecules of ATP
occurs in cytoplasm of cell, doesn’t require oxygen
If no oxygen is present, pyruciv acid goes to lactic acid
lactic acid goes to liver nd recombines with oxygen to make glucose
Aerobic respiration
Krebs cycle= citric acid cycle
series of reactions where pyruvate is completely broken down to CO2.
Krebs cycle make 2 ATP, electron transfer makes 34 ATP
in mitochondria, requires oxygen
lactic acid
during high intensity exercise, O2 can’t be supplied fast enough, so muscles burn glucose anaerobically, producing lactic acid
lactic acid build up in muscle is toxic and causes fatigue and pain
lactic acid is taken by the blood to the liver where it is recombined to form glucose then glycogen (storage form of glucose)
after exercise breathing is heavy so oxygen can be repaid
recovery oxygen: oxygen required after exercise
functions of blood
- transport nutrients and oxygen to cell
- transport co2 and wastes away from cell
- transport hormones to cells
- regulate pH
- thermoregulation
- protect against disease (WBC)🦠
- clotting to prevent blood loss
- maintain water and ion content in bodily fluids 💦
blood composition
liquid: plasma 55%
non-liquid: formed elements 45% (cells and cell fragments)
erythrocytes
RBC
suited for o2 and co2 transport
have HGB (protein) and has no nucleus to make room for it ( when combine with o2, HGB is red)
large SA to V to speed up gas exchange
made in bone marrow, destroyed in liver/spleen by macrophages (120 days)😩
small, 8um and flexible to go through narrow capillaries
- contain Hgb which combines with oxygen
- have no nucleus, more room Hgb
- biconcave disc shape: increases surface area for gas exchange and thicker edges= large volume for HGB
leucocytes
fight infections/provide immune responses
granulocytes: granular cytoplasm, lobed nucleus
agranular: lymphocytes and monocytes
macrophage is type of monocyte- phagocytic
few minutes to YEARS!!
get rid of dead or injured cells 😭(RIP) and invading microorganisms 🦠
thrombocytes
small cell fragments with no nucleus😔
1/3 of RBC🖕👌
made in bone marrow life span of a week
important in coagulation
plasma
91% water
rest is dissolved substances
glucose, AA, ions, wastes (urea: waste of protein metabolism), gases
oxygen transport
3% dissolved in plasma
97% carried in HGB to make oxyhemoglobin
this bond is v loose to breaks down easily to release oxygen
when o2 conc is high (capillaries in lungs), o2 combines with HGB easily
when o2 conc is low (cells) oxyhemoglobin breaks down
carbon dioxide transport
8% dissolved in blood plasma
22% combines with HGB to form carbaminohaemoglobin
70% carried in plasma as bicarbonate ions (HCO3-) (H+)
co2 diffuse into plasma because of con grad, most of it reacts with water to from carbonic acid. this then dissociates into hydrogen ions and bicarbonate ions
in lungs:
8% diffuses out
22% breakdown then diffuse
70% ions recombine to carbonic acid then breaks down by enzymes to water and co2, then diffusion
arteries
carry blood away from the heart
carry oxygenated blood
have thick, smooth, muscular walls with elastic fibres
no valves
high pressure blood because it is closer the heart, increase as ventricles contact
further down in skin because it contains high pressure blood
veins
carry blood toward the heart
carry deoxygenated blood
thin, relatively inelastic (pressure is constant) walls with little muscle
have valves
blood is under low pressure because most of the pressure is lost as it flows through the tiny capillaries
no elasticity
capillaries
Microscopic
connects veins and arteries
network
1 cell thick: thin for easy diffusion of nutrients and wastes
vasoconstriction/dilation
walls are made of smooth muscle and elastic fibres (stretch and recoil). the recoil keeps blood moving and maintains pressure
Vasoconstriction: contraction to reduce the lumen (inside space) size/diameter of artery to reduce blood flow to an area. reduce loss of body heat in cold temperatures, arteries constrict to let less blood go to the skin and more in the core region.
vasodilation: relaxing to increase lumen size, increase blood flow to an organ.In the heat, blood vessels close to the surface of the skin enlarge. This process is called vasodilation . This allows more heat to be lost from the blood.
adrenaline causes vasoconstriction in most arterioles, but vasodilation in skeletal/cardiac muscle
systole and diastole
systole: when heart muscles contract, pumping
diastole: when heart muscles relax, filling
artrial systole/ventricular diastole: atria contracts forcing blood into ventricles
ventricular systole/ atrial dyastole: atria relax and refill while ventricles contact which forces blood into arteries
cardiac output
=stroke volume x heart beat
stoke volume= volume of blood forced from a ventricle each contraction
cardiac output= amount of blood leaving leaving a ventricle every minute
sinoatrial node
collection of nerve cells in the wall of the right atrium
pacemaker
starts each cardiac cycle by sending nervous impulses which cause the atria walls to contracts, nerve impulses reach the atrioventricular node causing ventricles to contract-> frequency of this is called heart rate
vaso and exercise
when you exercise, large increase in blood flow Is needed to supply oxygen and nutrients and remove carbon dioxide and heat
vasodilation of blood vessels in muscles and contraction to blood vessels
started by anticipatory response from nervous system
continued because wastes (CO2, lactic acid, heat) all act as vasodilators
antigen
protein molecules of the surface of erythrocytes that determine blood type
capable of stimulating formation of antibodies
antibodies: molecules in plasm that remove foreign bodies (pathogens)
leucocytes then engulf and destroy inactivated pathogens
specific to each pathogen
Rh factor
a further antigen on erythrocyte surface
rh- doesn’t have antigen and makes antibodies that destroy the Rhesus factor
rh+ person has the antigen that makes no antibodies that destroy the Rhesus factor
antibody for rh is not normally present in plasma only produced after exposure to it. 1st exposure sensitises person, so nay subsequent exposure leads to rapid production of antibodies
if wrong blood type is given
antibodies in plasma combine with antigens on the surface of foreign blood Agglutination occurs (clumping of cells)
7 types of blood transfusions
whole blood: blood taken with anti-clotting agent added (eliminates disease risk)
Autologous: patienst own blood used that was collected before surgery
red cell concentrate: blood centrifuged and only erythrocytes taken (anaemic/heart disease)
plamsa: used to provide extra clotting factors in severe bleeding and liver disease
platelets: when platelets are too low
Cryoprecipitate: plasma frozen and slowly thawed. contains many clotting factors and used for haemophiliacs
Immunoglobulins: group of proteins acting as antibodies extracted from blood of people that are immune to a particular disease.
blood clotting and defence
- injury to lining of a blood vessels exposes a rough surface to which plackets stick to
- sticking platelet attract others, so a plug is built at the site of the injury
- platelets release vasoconstricttors that enhance constriction of damaged vessels
^for small injuries - blood clotting factors form a fibrin cloth reinforces the seal. fibrin cloth form a mesh that traps blood cells
after clot is formed, clot retraction occurs(threads contract, pulling damaged blood vessel edges together,) as this occurs a fluid called serum is squeezed out. then scab formed–>acts as a mechanical barrier to the entry of pathogens.
blood coagulates to prevent blood loss from injured tissue.
clotting factors catalyse the conversion of plasma protein to an active enzyme
nose structure and function
nasal cavity with l&r chamber (nostrils) that lead to pharynx
projections known as conchae increase surface area
filters (hair), warms (capillaries), moistens (mucus) the air before it enters the lungs
has olfactory receptors
enhances sound produced in speech
mucus and hair trap dust
pharynx
air from nasal cavity passes through here
13cm, direct air to larynx
used to pass food to oesophagus
larynx
stretched between cartilage are two folds of mucus membrane called vocal folds
the edges have elastic ligaments that vibrate (vocal chords)
trachea
has c-shaped cartilage bands that allowing the oesophagus to expand into the gaps in the trachea when swallowing
lined with ciliated mucus membrane to trap solid particles
mucus is produced from goblet cells
bronchi
where trachea divides into secondary and tertiary bronchi
kept open with cartilage and lined with cilia and mucus
bronchioles
very fine tube that lead to the alveoli
walls of smooth muscle, no cartilage
alveoli
around 300 million each lung
tiny air sacs, in clusters, wall have very thin membrane for diffusion
1 cell thick, large sa
surrounded by dense network of capillaries
chemical surfactant coats the inside alveoli to lubricate it and prevent friction and closing of alveoli
lung structure
right has 3 lobe
left has 2 lobe
pleura membrane covers surface of lungs and inside of chest. between 2 layers of membrane is pleural fluid which hold lung against inside of chest wall and allows lungs to slide along wall when breathing
intercostal muscles
muscles between ribs, internal and external
when the external muscles contract they they pull the ribs upwards and outwards, increasing volume of thoracic cavity
contraction of the internal muscles pulls ribs closer, decreasing the thoracic cavity. this increase pressure inside lungs and air is diffused out
diaphragm
dome shaped muscle
contraction increases volume of thoracic cavity
how lungs are specialised for gas exchange
x5
- alveoli give lungs a very large internal surface area, so lots of gas can be exchanged in a short amount of time
- each alveoli is well supplied with blood vessels, so that as much blood as possible is close to the air in the alveolus. the continuous flow of blood helps maintain a difference in concentration of o2 and co2 in blood and lungs. concentration gradient is necessary for diffusion
- wall of alveolus is very thin (1 cell thick), gas doesn’t have to travel far when moving in and out of blood.
- lungs positioned deep inside body to prevent excessive evaporation of fluid that covers the respiratory surfaces, it is important that the alveolus membrane is covered by a thin layer of moisture because gases can only diffuse in and out of the blood when they are dissolved in fluid.
- the lung volume can be changed by movements of the respiratory muscles, so that the air is made to move in and out of lungs. constant changing of air in the alveoli helps to ensure that there s always a difference in o2 and co2 concentration in the lungs and blood.
gas exchange in alveolus
blood in capillaries is from the pulmonary arteries.
this blood has low level of oxygen, lower than the concentration of oxygen in the alveolus. oxygen dissolves in the moisture on the inside of the alveoli and diffuses through the membrane through capillary walls and into blood.
the blood arriving at alveoli has high concentration of co2. (waste from cells) so the concentration of co2 in capillaries is higher than the concentration in the alveolus. co2 diffuse out of blood and into the alveolus. this is why the expired air has more co2
how is concentration gradient for O2 and CO2 maintained?
constant flow of blood through capillaries.the new blood pumped is low in o2 and high in co2 so conc grad is maintained
constant movement of air in and out of lungs. the air is high in o2 and low in co2
inspiration
pressure in lung must be less than atmospheric pressure, this is done by increasing lung volume
diaphragm and external intercostal muscles contract
diaphragm flattens and EIM contraction causes ribcage to move up and out
as pleura sticks to internal wall of chest cavity the lungs expand with it
air flows in til pressure is equal
expiration
diaphragm and external intercostal relaxes
diaphragm bulges more into chest cavity and ribcage moves down
reduces thoracic cavity
air flows out til equal
forced breathing: intercostal muscles contract to actively lower ribcage
mouth
mechanical:
jaw and teeth cut, tear, crush and grind food
tongue mixes it up with mucus into a round lump called bolus
chemical:
salivary amylase ptyalin begins starch breakdown
large starch molecules to smaller ones
salivary glands
3 types, 2 of each
- parotid salivary gained (front of ear)
- sublingual salivary gland (under the tongue)
- sub mandibular salivary gland (under mandible bone)
teeth
incisors: (4) biting and cutting, chisel shaped
canines: (2) tearing, pointy edge
premolars: (4) crushing and grinding
molars: (6) crushing and grinding
32 together
food swallowed
bolus is pushed into pharynx by tongue
oesophagus: made of mucosa, muscle (circular and longitudinal)
oesophagus pushes food from the mouth to the stomach by a wave of circular, muscular contractions called PERISTALSIS. movement lubricated by mucosa, prevents friction
stomach
after passing the diaphragm, the oesophagus reaches the stomach
mechanical:
waves of muscular contraction churns food and mixes it with gastric juices (HCl and enzymes) into thick soupy liquid called chyme
stomach has third muscle (oblique) to assist with churning
chemical:
gastric juices made in gastric glands of mucosa, contains enzyme pepsin (gastric protease) that begins protein breakdown. pepsin works in acidic conditions, that’s why it need activated by Hal to go from pepsinogen to pepsin
absorption: only alcohol and drugs absorbed in to blood
stomach wall lining
deep folds called rugae line stomach to help it expand to increase volume
first is the cardiac sphincter then it is the pyloric sphincter
thick mucus walls
stomach to small intestine
chyme goes into the duodenum (1st part of small intestine), through the pyloric sphincter (prevents food spilling into the duodenum too soon)
transferred by peristalsis (2-8hrs)
small intestine parts
- duodenum
- jejunum
- ileum
duodenum and jejunum
mechanical:
waves of muscular contractions (L&C walls of small intestine),churn the food, peristalsis
bile stored in gall bladder, and made in liver, is secreted through duct and emulsifies fats
chemical:
pancreatic juices from the pancreas enter the duodenum (pH8) and neutralises the chyme, contains enzymes
- pancreatic protease: proteins to amino acids
-pancreatic amylase: carbohydrates to simple sugars
-pancreatic lipase: fats to fatty acids and glycerol
intestinal juice fro intestinal glands in the mucosa completely chemical digestion
bile
emulsifies fats (breaks them down to tiny droplets, doest chemically change it)
has salts in it, not an enzyme
travels via duct to duodenum, helps neutralise chyme
increases surface area of fats so pancreatic lipase cancan quicker
ileum
most products of digestion (V+M, H2O) are absorbed into the blood capillaries of the villi through diffusion, osmosi and active transport (depends on conc)
fast and fat soluble vitamins absorbed into the lacteals of the lymphatic system and transported to the chest, where they enter the blood and go to the liver
lacteals are permeable to larger fat molecules
villi and microvilli in small intesine increase surface area to increase absorption rate
large SA of small intestine
very long (6m)
inner mucosa lining has many folds
mucosa has villi on it, cells covering villi have further projections (microvilli)
has dense network of capillaries to absorb nutrients
epithelium is very thin (1 cell thick)
ileum to large intestine
waste products of digestion go through large intestine
1.5 m long, no villi but mucosa is secreted to lubricate
bacteria breakdown remaining organic compounds
vitamins, minerals and water absorbed into blood, leaving contents semi-solid
faeces stored in rectum and eliminated through anus
faeces consists of, undigested cellulose, bacteria, bile, pigments, cells.
FUN FACT: cellulose stimulates movements of the alimentary canal.
large intesine structure
caecum (appendix is attached) appendix (lymphatic tissue) ascending colon, transverse colon, descending colon sigmoid colon rectum anus
villi and absorption
fatty acids + glycerol: diffusion into lacteal
AA: active transport
water and water soluble vitamins: diffusion
simple sugars: active transport
lymph and fluid balance
at the atrial end of the blood capillary, fluid tends to leak because of high pressure, some fluid returns at the venous end of capillary, the rest of the fluid now in tissues is returned as lymph.
clear watery liquid formed from interstitial fluid (between cells). help destroy dangerous bacteria
90% of this fluid goes back into the blood capillaries and the rest enters the lymphatic vessel (interstitial fluid in a lymphatic vessel is called lymph)
the lymph capillaries lined with overlapping epithelial cells that allow fluid to enter. Capillaries open to large vessels, often with valves to prevent back flow
lymph nodes
occur at intervals along lymphatic vessels
where lymph vessels carry lymph to
surrounded by capsule of connective tissue
large particles are trapped in meshwork of fibres as lymph flows through spaces in lymph node
lymphocytes and macrophages (phagocytosis) are produced to fight off invaders in lymph.
what happens to lymph after lymph node
sent through the efferent vessel and sent through the right lymphatic or thoracic duct where merges with the veins and the fluid reenters the circulatory system
organs of excretory system
lungs: release co2 and h20 vapour from cellular respiration
liver: convert substances in form we can excrete
skin: sweat glands, removes waste, and sweat for cooling, salt. contains byproducts
alimentary canal: passes out bile pigments from breakdown of haemoglobin to faeces
kidney: principal excretory organ, filters blood stream to remove toxic waste products
skin
main function is protection and temperature regulation and excretion of wastes
epidermis (closely packed epithelial cells/tissues)
dermis (connective tissue) has sweat glands, hair follicles, nerves and capillaries
subcutaneous layer (innermost skin layer)
sweat glands excrete 500ml of water a day contains salts, urea, lactic acid, drugs
sweat glands are found in lower layers of skin, a duct carries sweat to a hair follicle or skin surface where it opens at a pore. cells surrounding glands contract and squeeze the sweat to the skin surface
deamination
if other energy sources have been used up, body can metabolise large amounts of protein.
main byproduct of breaking down proteins is ammonia (NH3), excess protein in diet can’t be stored
deamination: removal of the amino group from excess amino acid molecules in the liver forming ammonia
AA + O2 —(enzymes)–> carbohydrate + ammomnia
ammonia is toxic so they are made into urea (less toxic molecule)
the carbohydrate is broken down into energy
energy + CO2 + NH3 —-> UREA + H2O
ammonia is converted to urea compound made by CO2 and NH3 in the liver.
urea circulates in blood and is filtered out by kidneys
urea is low toxicity so it needs water to dissolve it in and get rid of it (urine)
worn out cells are a source of protein and are broken down into AA
liver functions
- deamination
- detoxification: alcohol, drugs, antibiotics
- hormone removal, deactivates and converts to a form to be excreted
- dead RBC and haemoglobin are broken down in liver and passed out with faeces
- carbohydrate metabolism: excess glucose turned to glycogen for storage and glycogen turned back to glucose when needed. depends on body needs
- lipid metabolism: excess carbs to fat
- heat production, main heat producing organ in body
- production of bile: emulsifies fat in duodenum
- stores vitamins and minerals
- protein synthesis
fluid contents in kidney
water most abundant in body 40-80%
intracellular and extracellular fluid
water intake=water outputs
amount of water consumed and urine formed is regulated by brain receptors and ADH hormone (antidiuretic hormone) which target nephrons and stops them from releasing water through urine
ADH produced when body is dehydrated
regions of the kidney
renal cortex:outer position, dark red, contains bowman’s capsule
renal medulla: innermost region, holds renal pyramids (8-18), loop of henle, pale pink
renal pelvis: inner layer, cream colour, collects urine from collecting ducts -> 3 major calyces-> renal pelvis before it goes to bladder. acts as funnel for urine flow into ureter
nephron
microscopic
functional unit of kidney
nephron = glomerular capsule + renal tubule (5cm long) + associated blood supply
I million nephrons each kidney
sections of nephron
- renal corpuscle (glomerular capsule)
- proximal convoluted tubule.
descending limb of loop of henle - loop of henle
ascending limb of loop of henle - distal convoluted tubule,
- collecting ducts
renal corpuscle
consists of glomerulus (knot of capillaries) inside glomerular capsule (double walled cup that that surrounds glomerulus)
afferent: enters, arteriole going into RC
efferent: away, arteriole leaves glomerulus
filtration takes place in real corpuscle
blood flow in nephron
- renal artery (blood from aorta) divides into afferent
- afferent arteriole forms knot of capillaries (high bp)
- efferent arteriole breaks up into network of capillaries called peritubular capillaries
- peritubular capillaries surround PCT, desc and asc limb of LOH and CD
- venule
- renal vein to inferior vena cava
things get squirted out from glomerulus to glomerular capsule
steps of urine transformation
glomerular filtration
selective reabsorption
tubular secretion
glomerular filtration
high BP in GC is due to the afferent arteriole having a wider diameter
efferent arteriole leaving glomerulus is narrower, resistance to blood flow
High BP forces small ions, glucose, AA, H2O, through capillary walls and into bowman capsule space
large molecules, (RBC, large proteins), remain in capillaries
the filtrate is collected by Bowmans capsule and enters tubule
selective reabsorption
of filtrate by cells that line renal tubule (H20, salts, glucose, AA, vitamins, minerals, ions)
water leaves membrane on descending part of LOH
Na and Cl reabsorbed on ascending limb of LOH (so doesn’t lose more water)
under hormonal control of ADH where more or less water can be reabsorbed
facultative reabsorption: active reabsorption of H20, ATP is needed
ADH causes kidneys to retain water (alcohol interferes with this action
tubular secretion
adding materials/molecules to filtrate
active transport
peritubular secretion into tubes of nephron, last chance for unwanted materials to leave the body
remove H ion to regulate pH
removes ammonium ions as well
water and other substances not reabsorbed drain forms the collecting ducts into renal pelvis to ureter and bladder
ADH in kidneys (CD), to remove water from urine, decrease urine output, makes urine more concentrated
dark yellow instead of pale yellow
structure and function of nephron
- glomerular capsule surround glomerulus to collect fluid filtered out of blood capillaries
- arteriole leading out of glomerulus is narrower, so this raises BP so more fluid is filtered out of blood
- tubule has 2 sets of convolutions and a long loop so that each tubule has a large SA for secretion and reabsorption
- 1 million nephrons each kidney, increase surface area for reabsorption
urine composition
0.5 litres per day lost to remove wastes
more water leads to increase urine output and decrease in concentration
99% of water reabsorbed
no protein
no glucose
contains uric acid (breakdown of nucleic acids)
and creatinine (breakdown of creatine phosphate)
96% water
2% urea
1.5% various ions
0.5% other (creatinine, uric acid)
tranport in glomerular filtration
passive: water urea glucose AA vitamins salts
transport in selective reabsorption
passive:
water
active: salts glucose AA vitamins Na, Cl ions
transport in tubular secretion
active: H ion NH4 ion creatinine toxins drugs (penicillin) neurotransmitters UREA water (under ADH influence)
function of musculoskeletal system
movement
postural support
heat production during cold stress (shivering)
properties of muscle unique to other cells
x4
- contractibility: cable of getting shorter, contracts and relaxes
- extensibility: can be stretched
- elasticity: when stress is removed, they return to original shape/length (recoil)
- excitability: nerve stimulations, muscles are activated by nerve impulses from the brain
microstructure of muscle cell
muscle cell is an elongated cyclinder that lie parallel to each other, many nuclei and mitochondria and has sarcolemma and sarcoplasm.
made of bundles of muscle fibre held together by connective tissue.
connective tissue have hundreds of myofibrils which is made of myofilaments which is made of actin and myosin
