mass transport in animals

Question 1

Describe the role of red blood cells and haemoglobin in oxygen transport

Answer 1

Red blood cells contain lots of haemoglobin (Hb) - no nucleus, biconcave, high SA:V, short diffusion path
● Hb binds with O2 gas exchange surfaces where partial pressure of O2 (pO2) is high
● This forms oxyhaemoglobin which transports O2 (each can carry 4O2 - one at each Haem group)
● Hb unloads O2 near cells / tissues where pO2
is low

Question 2

Describe the structure of haemoglobin

Answer 2

●Globular protein with a quaternary structure
● Made of 4 polypeptide chains
● Each chain contains a Haem group containing an iron ion (Fe
2+

Question 3

Describe the structure of haemoglobin

Answer 3

●Globular protein with a quaternary structure
● Made of 4 polypeptide chains
● Each chain contains a Haem group containing an iron ion (Fe
2+

Question 4

Describe the loading, transport and unloading of oxygen in relation to the
oxyhaemoglobin dissociation curve in areas with low ppO2 (respiring tissues)

Answer 4

Hb has a low affinity for O2
● So O2 readily unloads dissociates with Hb
● So % saturation is low

Question 5

Describe the loading, transport and unloading of oxygen in relation to the
oxyhaemoglobin dissociation curve in areas of high ppO2 (gas exchange surfaces)

Answer 5

● Hb has a high affinity for O2
● So O2 readily loads with Hb
● So % saturation is high

Question 6

Describe evidence for the cooperative nature of oxygen binding

Answer 6

A low pO2 as oxygen increases there is little / slow increase in % saturation of Hb with oxygen
○ When first oxygen is binding
● At higher pO2
, as oxygen increases there is a big / rapid increase in % saturation of Hb with oxygen
○ Showing it has got easier for oxygens to bind to

Question 7

Explain why different types of haemoglobin can have different oxygen transport properties

Answer 7

Diff types of Hb made of polypeptide chains with slightly different amino acid sequences.
● meaning different tertiary / structures and shape→ different affinities for oxygen

Question 8

What is the Bohr effect?

Answer 8

Effect of CO2 concentration on dissociation of oxyhaemoglobin → curve shifts to right

Question 9

Suggest the importance of a double circulatory system

Answer 9

● Prevents mixing of oxygenated / deoxygenated blood
*So blood pumped to body is fully saturated for aerobic respiration
● Blood pumped to body at a higher pressure (after being lower from lungs)
○ Substances taken to and removed from body cells quicker

Question 10

How does the double circulatory system help allow blood to be pumped at higher pressures

Answer 10

Double circulatory system consists of:
pulmonary circulatory- blood to lungs
systematic circulatory- blood from lungs to around body
They operate at different pressures (systematic higher) as it has to pump blood around the body

Question 11

Role of Vena Cava

Answer 11

Transports deoxygenated blood from respiring tissues to heart

Question 12

Pulmonary Artery Role

Answer 12

Transports deoxygenated blood from heart to lungs

Question 13

Pulmonary Vein Role

Answer 13

Transports oxygenated blood from lungs to heart

Question 14

Aorta Role

Answer 14

Transports oxygenated blood from heart to respiring tissues

Question 15

In what order is blood transpoted in the heart?

Answer 15

Deoxygenated:
*deoxygenated lood enters vena cava from respiring tissues
*deoxy blood travels to the right atrium.
*right atrium contracts, blood passes through semi lunar valve to right ventricle
*right ventricle transports blood to pulmonary arteries to lungs
Oxygenated:
*oxygenated blood enters heart by pulmonary vein
*passes through semi lunar valve to left atrium to left ventricle where its pumped out the aorta to the respiring cells

Question 16

What’s the general pattern of blood circulation in a mammal

Answer 16

Deoxy:
Renal veins – deoxygenated blood to vena cava from kidneys
and process continues…
Oxygenated:
Renal arteries – oxygenated blood from aorta → kidneys

Question 17

Suggest why the wall of the left ventricle is thicker than that of the right

Answer 17

● Thicker muscle to contract with greater force
generate higher pressure to pump blood around entire body

Question 18

Suggest why the wall of the left ventricle is thicker than that of the right

Answer 18

● Thicker muscle to contract with greater force
generate higher pressure to pump blood around entire body

Question 19

Whats tissue fluid

Answer 19

*plasma tht has been transported out of pores of capillaries

Question 20

Whats the difference between tissue fluid and plasma

Answer 20

Tissue fluid contains fewer proteins because proteins are large and arent able to go thru capillary pores

Question 21

Whats the role of veins

Answer 21

Veins carry blood to the heart at low pressure
*receive blood that has passed thru capillary networks

Question 22

Structure of veins and explain why

Answer 22

Veins have
*wide lumen- less resistance to blood flow
*thin layer of muscle and elastic fibers- lower blood pressure
*thinner wall compared to arteries
*contains valves

Question 23

Structure of arteries and explain why

Answer 23

*narrow lumen- miantain high pressure
*thick layer of muscle, elastic fibers- allows wall to contract and recoil when heart relaxes.
*thick arterial walls- wiyhstand high pressure

Question 24

Function of arteries

Answer 24

carry blood AWAY from the heart

Question 25

Function of capillaries

Answer 25

allow efficient exchange of substances between blood and tissue fluid (exchange surface)

Question 26

Structure of capillaries and why

Answer 26

*one cell thick- short diffusion distance from 02 and C02 in blood
*small diameter/lumen- reduces blood flow rate so more time for diffusion
*pores in wall- allow plasma to leak out and form tissue fluid.
*Capillary bed is a large network of branched capillaries → increases surface area for diffusion

Question 27

Explain the return of tissue fluid to the circulatory system

Answer 27

At the venule end of capillaries:
*Hydrostatic pressure reduces as fluid leaves capillary
* cause of water loss increasing conc of plasma proteins lowers water potential in tissue fluid
*Water enters capillaries from tissue fluid by osmosis down a water potential gradient
*Excess water taken up by lymph capillaries ,returned to circulatory system through veins

Question 28

Give pathway blood takes when travelling the human circulatory system from the kidneys to the lungs.

Answer 28

Renal vein
Vena cava to right atrium
Right ventricle to pulmonary artery

Question 29

Give pathway blood takes when travelling the human circulatory system from the kidneys to the lungs.

Answer 29

Renal vein
Vena cava to right atrium
Right ventricle to pulmonary artery

Question 30

explain how an arteriole can reduce the blood flow into capillaries

Answer 30

muscle contracts and constricts lumen

Question 31

explain how an arteriole can reduce the blood flow into capillaries

Answer 31

Muscle contracts and constricts lumen

Question 32

Explain the role of the heart in the formation of tissue fluid

Answer 32

*contraction of ventricle produces high hydrostatic pressure which forces the water out

Question 33

Lymphoedema is a swelling in the legs which may be caused by a blockage in the lymphatic system. Suggest how a blockage in the lymphatic system could cause lymphoedema

Answer 33

Excess tissue fluid can’t be reabsorrbed

Question 34

Give 2 structural features of an aorta wall and explain how they are related to the function of an aorta

Answer 34

(Smooth) muscle resists/withstands high blood pressure;
2. Elastic (tissue/layer) stretches and recoils maintains/smooths blood pressure;
3. (Smooth) endothelium reduces friction;
4. Protein (coat) prevents (artery) wall splitting

Question 35

The hydrostatic pressure falls from the arteriole end of the capillary to the venule end. Explain why

Answer 35

Loss of water / loss of fluid / friction (against capillary lining).

Question 36

High blood pressure leads to accumulation of tissue fluid. Explain how

Answer 36

High blood pressure = high hydrostatic pressure;
2. Increases outward pressure from (arterial) end of capillary
3. (So) more tissue fluid formed / less tissue fluid is reabsorbed.
Allow lymph system not able to drain tissues fast enough

Question 37

Water potential of the blood plasma is more negative at the venule end of the capillary than the arteriole end of the capillary. Explain why

Answer 37

Water has left the capillary;
2. Proteins (in blood) too large to leave capillary;
3. Increasing / giving higher concentration of blood proteins (and thus wp).

Question 38

Explain how the structure of arteries relates to their function

Answer 38

*Thick smooth muscle tissue can contract withstand blood flow / pressure
*Thick elastic tissue Can stretch as ventricles contract and recoil as ventricles relax, to maintain high pressure

Thick wall Withstands high pressure / prevents bursting
Smooth / folded endothelium Reduces friction
Narrow lumen maintains high pressure

Question 39

Explain how the structure of arterioles relates to their function

Answer 39

Function – (division of arteries to smaller vessels which can) direct blood to different capillaries / tissues]

● Thicker smooth muscle layer than arteries
○ Contracts → narrows lumen → reduces blood flow to capillaries
○ Relaxes → widens lumen → increases blood flow to capillaries
● Thinner elastic layer → pressure surges are lower (as further from heart / ventricles)