Mass transport in animals

Question 1

how do you know haemoglobin is a protein

Answer 1

Has 4 polypeptide chains (quaternary structure) each associated with a haem group (contains iron) which combines with 1 oxygen molecule

Question 2

describe the binding of oxygen and haemoglobin

Answer 2

• 1 haemoglobin has 4 polypeptide chains so can combine with 4 oxygen molecules
• Binding of first oxygen causes a change in shape which makes further binding easier
• Binding of last oxygen is less likely so requires a higher p.O2

Question 3

when does haemoglobin load O2

Answer 3

• Associates at high p.O2 in the lungs

Haemoglobin has high affinity for O2

Question 4

when does haemoglobin unload O2

Answer 4

Dissociates at low p. O2 when there is a higher concentration of CO2 as it reduces haemoglobin affinity for O2

Question 5

how are there different types of haemoglobin

Answer 5

sequence of amino acids determines shape

Question 6

type of haemoglobin in active animals

Answer 6

• Active animals have haemoglobin which readily release oxygen to respiring cells
o Lower affinity for oxygen = shift to the right

Question 7

type of haemoglobin in small animals

Answer 7

• Small animals have large surface area to volume ratio
o Lower affinity for oxygen = shift to the right
o Lose heat faster so have greater rate of respiration
o Enough O2 for respiring tissues

Question 8

type of haemoglobin in animals living in high altitudes

Answer 8

• Animals at high altitudes (where oxygen is scarce) have haemoglobin which readily combine with oxygen
o Higher affinity for oxygen = shift to the left
o Low partial pressure of O2 in the lungs
o Haemoglobin is able to load more oxygen at same O2 partial pressure
o Enough O2 for respiring tissues but difficult to dissociate

Question 9

partial pressure

Answer 9

how much oxygen is available to be taken up

Question 10

how does CO2 affect haemoglobin

Answer 10

Respiring cells make CO2 that dissolve in plasma to form carbonic acid

More CO2 dissolves with H2O to increase H+ ion concentration so lower pH

More acidic means lower affinity (attraction) of O2 to haemoglobin

Changes shape of haemoglobin

Oxygen is free to dissociate to and diffuse into respiring cells

Question 11

Bohr effect

Answer 11

oxygen dissociation curve shifts to the right when more CO2 or H+ ions are present

Question 12

explain the foetus haemoglobin being different to the mother’s

Answer 12

Foetus has ODC shifted to the left of mother so foetal haemoglobin has a higher affinity for oxygen so oxygen can move from mother to foetus respiring cells

Question 13

pulmonary circulation

Answer 13

from heart to lungs to pick up oxygen

Question 14

systemic circulation

Answer 14

take oxygenated blood to the rest of the body

Question 15

arteries (3)

Answer 15

No valves and normally carry oxygenated blood (except PA) away from heart

Thick layer of muscle allows constriction and dilation

Thick elastic layer allows stretch and recoil to withstand high pressures

Question 16

arterioles (2)

Answer 16

Pressure decreases so have fewer elastic fibres

Circular muscle fibres: vasoconstriction and vasodilation

Question 17

capillaries (3)

Answer 17

One cell thick (short DP) for rapid exchange between blood and cells

Many and highly branched increases surface area

Endothelial cells have spaces for white blood cells to pass through

Question 18

veins (3)

Answer 18

Normally carrying deoxygenated blood (expect PV) back to the heart

Thin muscle and elastic layer

Low pressure blood so has valves for one directional flow

Question 19

systole

Answer 19

heart contraction

Question 20

diastole

Answer 20

heart relaxation

Question 21

myogenic

Answer 21

Coronary arteries supply cardiac muscle with oxygen and is able to contract without nervous stimulation

Question 22

compare the left ventricle with the right one

Answer 22

Left ventricle as thicker muscle so stronger/ more contractions causing higher blood pressure

Question 23

what would occur if there was a hole between the left and right side of the heart

Answer 23

oxygenated blood and deoxygenated blood mix so lower volume of oxygenated blood leaves left ventricle

Question 24

cardiac cycle

Answer 24

1. Diastole:
   - Ventricles are relaxed so blood enters atria and pressure rises
   - When pressure in the atria is higher than in the ventricles, atrioventricular valves open allowing blood into the ventricles
2. Atrial systole:
   - Atrial walls contract to force blood into ventricles
3. Ventricular systole:
   - Ventricular walls contract increasing pressure
   - Atrioventricular valves close preventing blood from re-entering atria
   - When pressure in ventricles are higher than in the arteries, semi-lunar valves open and blood is forced out of the heart

Question 25

cardiac output

Answer 25

volume of blood pumped in 1 minute

Question 26

stroke volume

Answer 26

volume of blood pumped in 1 beat on one side of the heart

Question 27

equation connecting cardiac output, stroke volume and heart rate

Answer 27

Cardiac output=stroke volume x heart rate

Question 28

how is heart beat controlled

Answer 28

1. Sinoatrial node in right atrium acts as a pace maker
   - Generates action potential which spreads across the atria causing it to contract
2. Action potential passes through the atrioventricular node (patch of tissue) into the ventricles (septum does not conduct impulses)
3. Passes down a group of fibres called purkinje fibres (collectively, Bundle of His)to the base of the ventricles
   - Ventricles start contracting from the bottom so there is no blood trapped at the bottom of the ventricles

Question 29

maintaining one-way flow (2)

Answer 29

Contractions in certain areas of the heart lead to high pressure in that area

Valves prevent backflow of blood

Question 30

hydrostatic pressure

Answer 30

pressure of blood created by the heart which forces fluid out and stronger than osmotic pressure, decreases in pressure the further away from the heart

Question 31

water potential

Answer 31

pressure exerted by dissolved substances in the tissue fluid which draws water back into the blood

Question 32

how tissue fluid forms

Answer 32

• Blood has higher hydrostatic pressure than water potential so tissue fluid e.g. water and small molecules are forced out
o Proteins and red blood cells are not lost to tissue fluid – too big

• Hydrostatic pressure decreases along capillary (loss of water, further away from heart)
o Water potential outside capillary is greater than inside - presence of protein and loss of water in capillary
o Water enters blood by osmosis

Question 33

lymph vessels

Answer 33

drains remaining tissue fluid and large molecules, which are too large to enter capillaries

Question 34

how does smoking cause cardiovascular disease

Answer 34

CO binds to haemoglobin instead of O2

• Reduces O2 capacity of blood, heart needs to work harder, increase blood pressure
• Insufficient supply of O2 to heart muscle during exercise

Question 35

how does having high blood pressure cause cardiovascular

Answer 35

Heart works harder to pump blood in arteries

- More likely to develop an aneurysm which can burst causing a haemorrhage