exchange and transport systems b

Question 1

what is haemoglobin?

Answer 1

a large protein with a quaternary structure (4 polypeptide chains)
each chain has a haem group which contains an iron ion

Question 2

what does affinity for oxygen mean?
how many oxygens can bind to haemoglobin?

Answer 2

tendency to combine with oxygen
4

Question 3

what is the reversable reaction for oxygen association and dissociation?

Answer 3

haemoglobin + oxygen <-> oxyhaemoglobin
(Hb+ 4O2<-> HbO8)

Question 4

what is partial pressure of oxygen/ CO2
(pO2) (pCO2)

Answer 4

measure of oxygen/ carbon dioxide concentration. greater conc of dissolved O2/ CO2 the higher the partial pressure

Question 5

what does affinity for oxygen depend on?

Answer 5

the partial pressure of oxygen
oxygen loads onto haemoglobin to form oxyhaemoglobin where theres a high pO2
oxyhaemoglobin unloads its oxygen where theres a lower pO2

Question 6

think of a question for this

Answer 6

O2 enters blood cappilaries at alveoli which have a high pO2 so O2 loads onto haemoglobin to form oxyhaemoglobin
when cells respire, they use up O2 which lowers the pO2. rbc deliver oxyhaemoglobin into respiring tissues where it unloads oxygen
haemoglobin then returns to lungs to pick up more O2

Question 7

what is is an oxygen dissociation curve?

Answer 7

shows how affinity for oxygen varies and how saturated haemoglobin is with oxygen at any partial pressure

Question 8

describe oxygen dissociation curve

Answer 8

see poster on it

Question 9

what is the bohr effect?

Answer 9

haemoglobin gives up oxygen more readily at a higher pCO2
cells respire and produce CO2 so raise pCO2
increases rate of oxygen unloading so dissociation curve shifts right
saturation of blood with oxygen is lower for a given pO2 so more oxygen released
check book

Question 10

hoe does haemoglobin and dissociation curve change for different organisms

Answer 10

check book and text book

Question 11

what are the names of all the blood vessels entering and leaving the heart lungs and kidneys?

Answer 11

see page 74 of revision guide

Question 12

what does blood transport?

Answer 12

respiratory gases, products of digestion, metabolic waste and hormones

Question 13

why is the heart called a double circulatory system? what is the hearts blood supply called?

Answer 13

there are 2 circuits
one takes blood from the heart to the lungs and back to the heart and the other takes blood around the rest of the body
the left and right coronary arteries

Question 14

what are arteries?

Answer 14

blood vessels that carry blood away from the heart
thick muscular walls
elastic tissue to stretch and recoil to maintain pressure
endothelium (inner lining) is folded so artery can stretch maintaining high bp
all carry oxygenated blood apart from pulmonary artery

Question 15

what are arterioles?

Answer 15

arteries divide into smaller blood vessels which form a network
blood directed to diff areas of demand by muscles inside arterioles which contract to restrict the blood flow or relax to allow blood flow

Question 16

what are veins?
adaptations?
what do they carry?

Answer 16

blood vessels which carry blood to heart
wider lumen than arteries with very little elastic or muscle tissue
contain valves to prevent backflow
flow through veins helped by contraction of body muscles surrounding them
all carry deoxygenated blood except for pulmonary veins

Question 17

what are capillaries?
how are they adapted?

Answer 17

smallest blood vessel which arterioles branch into
substances exchanged between cells and capillaries so theyre adapted for efficient diffusion
-found very near cells in exchange tissues so short diffusion pathway
- walls one cell thick so short diffusion pathway
- lots of capillaries (form capillary bed) so large surface area

Question 18

what is tissue fluid?
what is it made from?
what is its role?

Answer 18

fluid that surrounds cells in tissues
made from small molecules that leave the blood plasma like water, oxygen, nutrients but not rbc or big proteins as they are too big to be pushed out of capillary walls
cells take in oxygen and nutrients from tissue fluid and release metabolic waste into it

Question 19

how is tissue fluid formed?

Answer 19

in capillary bed, substances move out of capillaries into tissue fluid by pressure filtration
1. at start of capillary bed, nearest arteries, hydrostatic pressure in cap is greater than tissue fluid
2. difference means overall outward pressure forces fluid out of capillaries and into spaces around cells forming tissue fluid
3. as fluid leaves, hydrostatic pressure reduces in capillaries so is lower at venule end
4. due to fluid loss and increasing conc of plasma proteins (which dont leave caps), the water pot at the venule end is lower than tissue fluid
5. so some water re-enters caps from tissue fluid at venule end by osmosis

Question 20

what happens to excess tissue fluid?

Answer 20

drained into lymphatic system which transports it from tissues and puts it back in circulatory system

Question 21

what can cause an accumulation of tissue fluid in the tissues?

Answer 21

high blood pressure as it creates a high hydrostatic pressure in the capillaries

Question 22

label a diagram of the heart
what does the right side pump?
what does the left side pump?

Answer 22

see poster
right- deoxygenated blood to lungs
left- oxygenated blood to whole body

Question 23

what does the left ventricle do?
how is it adapted?

Answer 23

thicker more muscular walls than right so it can contract powerfully enough to pump blood all the way around the body
right only needs to go to lungs

Question 24

why do ventricles have thicker walls than atria?

Answer 24

they have to push blood out of heart whereas atria just need to push blood into ventricles

Question 25

what are the AV valves?

Answer 25

link artery to ventricle and prevent backflow in atria when ventricles contract

Question 26

what are SL valves?

Answer 26

link ventricles to pulmonary artery and aorta and prevent backflow into heart after ventricles contract

Question 27

what do the cords do in the heart?

Answer 27

attach atrioventricular valves to pulmonary artery and aorta and stop blood flowing back into heart after ventricles contract

Question 28

when do valves open and close?

Answer 28

only open one way
higher pressure behind valve- forced open
higher pressure in front of valve- forced shut
means blood only flows one way through the heart

Question 29

what is the cardiac cycle?

Answer 29

ongoing sequence of contraction (systole) and relaxation (diastole) of the atria and ventricles that keeps blood continuously circulating

Question 30

what are the three simplified stages of the cardiac cycle?

Answer 30

1) ventricular diastole and atria systole
- ventricles relax and atria contract so decrease vol and increase press which pusses blood into ventricles. slight increase in ventricular pressure and chamber vol as ventricles receive blood from atria
2) ventricular systole and atria diastole
- atria relax and ventricles contract so decrease vol and increase press. press higher than atria so AV valve shuts. press in ventricles also higher than aorta/ pulmonary artery so SL valves open and blood forced into arteries
3) ventricular and atrial diastole
- ventricles and atria both relax. higher press in pulmonary artery and aorta closes SL valves to prevent bf. blood returns to heart and atria fill
again due to high pressure in vena cava and pulmonary vein. so, pressure in atria increases. ventricles continue to relax so pressure falls below pressure of atria so AV valves open and blood flows passively into ventricles. atria contract and cycle begins again

Question 31

explain the graph showing pressure in cardiac cycle

Answer 31

see poster

Question 32

what is digestion?

Answer 32

polymers being hydrolysed into monomers so that they are small enough to diffuse/ actively transport across a membrane to be absorbed into the blood

Question 33

what are carbohydrates broken down by?
where are these enzymes produced?

Answer 33

amylase- converts starch to maltose by hydrolysing glycosidic bonds
produced by salivary glands and pancreas

membrane bound disaccharides- enzymes attached to cell membranes of epithelial cells lining the ileum. help breakdown disaccharides into monosaccharides by hydrolysing glycosidic bonds eg maltose into alpha glucose

Question 34

what are lipids broken down by?

Answer 34

lipase catalyses breakdown into fatty acids and monoglycerides
made in pancreas but used in small intestine

bile salts produced by liver- emulsify fats to increase sa

once broken down, monoglycerides and fatty acids and bile salts join to form micelles