Mass Transport In Animals

Question 1

What does blood transport

Answer 1

• o2 from lungs to cells for resp
• hormones from glands to target organs
• co2 from cells to lungs to be removed
• waste products to kidneys + liver

Question 2

Structure of hb

Answer 2

• globular protein - quaternary structure (>1 polypeptide chain)
• contains iron that combines with o2
• contains alpha and beta chains + heme r group

Question 3

How are rbc adapted to transport o2

Answer 3

• biconcave disk - maximises sa for o2 to bind
• no nucleus - Inc space for o2 to bind
• contains hb - high affinity for o2
• flexible - squeeze through capillaries
• numerous

Question 4

Why is the oxygen dissociation curve s shaped

Answer 4

As 1st o2 molecule binds with difficulty, once one molecule binds causes a small change in conformation of hb and the subsequent 3 bind easily (resulting in a steep graph)

Question 5

What is the significance of the o2 dissociation curve

Answer 5

A relatively small decrease in pO2 leads to a huge drop in amount of o2 carried by the blood (decreased saturation of hb) meaning more o2 is available for respiring tissues

Question 6

How is co2 transported

Answer 6

• in solution in blood plasma
• combined with hb
• as hydrogen carbonate ions in plasma

Question 7

Causes of Bohr shift (right)

Answer 7

• Inc in pco2
• dec in ph
• Inc temp

Question 8

What is the significance of Bohr shift

Answer 8

At a given pO2 hb is less saturated with o2 than usual in an area which has higher pco2 lower ph and higher temp. Hb dissociates more readily under these conditions therefore active,y respiring tissues receive more o2 than those respiring less

Question 9

Advantage of Bohr shift

Answer 9

More o2 is released at the same pO2 so tissues receive more o2 for respiration

Question 10

What type of animal would need the curve to shift to the right

Answer 10

• high sa:v - looses heat - needs higher metabolic rate
• organism with high metabolic rate - needs more resp

Question 11

Names of the 3 o2 dissociation curves that are to left of normal

Answer 11

• foetal hb
• myoglobin
• high altitude mammals + seabed

Question 12

Why does foetal hb shift to the left

Answer 12

Foetal hb has a higher affinity for o2 than maternal hb. So f hb can bind with o2 more easily in lower partial pressures of o2 (+ more reluctant to dissociate). Which allows it to exchange o2 with the maternal hb

Question 13

Why is the myoglobin curve shifted to the left

Answer 13

Myoglobin only dissociates o2 at a very low pO2 (has a higher affinity for o2)

Question 14

Why does the curve shift to the left for high altitude mammals or seabed

Answer 14

PO2 dec with altitude, at high altitude is difficult to load hb with o2. Hb has a higher affinity with o2 inorder to load more o2 at lower pO2

Question 15

Where is the heart located + what’s special about it

Answer 15

Between lungs enclosed in pericardium
Never tires but can’t tolerate lack of o2

Question 16

Describe the double circulatory system

Answer 16

Blood comes into heart from body, passes into lungs to collect o2, returns to heart, leaves again to be transported to body

Question 17

Function of arteries

Answer 17

Carry blood away from heart

Question 18

Functions of capillaries

Answer 18

Allow exchange of materials between blood and body cells

Question 19

Functions of veins

Answer 19

Carry blood into heart

Question 20

Structure of arteries and veins

Answer 20

Have same basic 3 layered structure :outer middle inner

Question 21

What is the inner layer called + what is it

Answer 21

• tunica intima
• single layer of flattened endothelial cells
• smooth surface - dec friction — blood flows quickly
• IN ARTERIES endothelium is folded so can expand under high pressure

Question 22

What is the middle layer called and what is it

Answer 22

• tunica media
• contains smooth muscle and elastic fibres ( IN ARTERIES layer is very thick)
• smooth muscle - can contract + narrow lumen - dec blood flow into a cap bed (also Inc bp IN ARTERIES)
• elastic fibres - can stretch + recoil (maintains diastolic bp)

Question 23

What is the outer layer called and what is it

Answer 23

• tunica adventitia
• consists of elastic fibres and collagen
• collagen is tough so gives strength to vessel wall
• in larger veins and arteries layer contains small blood vessels

Question 24

Structure of capillaries

Answer 24

Walls that consist of a sing,e layer of flattened endothelial cells - diff dist is short for substances being exchanged

Question 25

What features of an artery allow it to withstand high pressure

Answer 25

- thick walls + lots of collagen fibres give it strength - folded endothelium + elastic fibres allows expansion — prevent damage to artery wall as result of high pressure -

Question 26

What features of an artery allow it to maintain pressure

Answer 26

- Elastic fibres recoil to put pressure on blood inside artery - smooth muscles contract to narrow the lumen (Inc pressure)

Question 27

What features of an artery allow it to control vol of blood flowing into capillary bed

Answer 27

- vasoconstriction (smooth muscles contract) - vasodilation (smooth muscles relax)

Question 28

Role of the coronary arteries

Answer 28

Supply o2 and glucose throughout cardiac muscle (some oxygenated blood leaves left ventricle and goes directly to the heart through coronary arteries)

Question 29

How does the cardiac muscle contract

Answer 29

Myogenically - without hormonal or nervous stimulation, stimulates own contractions

Question 30

Describe first part of cardiac cycle

Answer 30

Spontaneous cardiac impulse generated by sinoatrial node, the electrical impulse spreads through the walls of the atria leading to atrial systole

Question 31

Describe Second part of cardiac cycle

Answer 31

Signal then transmitted to the atrioventricular node, which delays the transmission of the impulse by 0.1 seconds to allow atria to contract fully, pushing blood into ventricles

Question 32

Describe 3rd part of cardiac cycle

Answer 32

The impulse is then transmitted to the bundle of his followed by the purkinje fibres, which conduct the impulse to the ventricles causing ventricular systole (blood forced out)

Question 33

What is atrial systole

Answer 33

Atria contract, semi lunar valves close, blood forces from atria to ventricle

Question 34

What is ventricular systole

Answer 34

Ventricle contracts, blood forced into arteries, bicuspid + tricuspid valves close

Question 35

What happens during diastole in heart

Answer 35

Heart relaxes and fills with blood from veins, semi lunar valves closed to blood entering arteries

Question 36

Why do ventricles contract from apex up

Answer 36

To ensure efficient emptying

Question 37

Describe the pressure time graph for the cardiac cycle (aorta)

Answer 37

Starts high but flat (during atrial systole), rises in curve along ventricle curve, comes back down a little (during ventricular systole), little lump then high but flat again (during diastole)

Question 38

Describe the pressure time graph for the cardiac cycle (left ventricle)

Answer 38

Starts low rises less than atria in curve (during atrial systole), steep incline then follows aorta curve (during ventricular systole), sharp drop then flattens out low with atria (during diastole)

Question 39

Describe the pressure time graph for the cardiac cycle (left atria)

Answer 39

Starts low rises in curve higher than ventricle (during atrial systole), little dip then little lump then big dip slowly rising until meets with declining ventricle (during ventricular systole), flattens with ventricle (during diastole)

Question 40

What is the equation for cardiac output

Answer 40

Cardiac output = hr x sv (stroke vol)

Question 41

Function of tissue fluid

Answer 41

Essential for efficient exchange of materials between blood and cells

Question 42

What is the lymphatic system

Answer 42

Acts as a drainage system for excess tissue fluid

Question 43

Describe what happens at the arteriole end (in terms of tissue fluid)

Answer 43

- blood has relatively high hydrostatic pressure (due to pumping of ventricles). This high pressure tends to force water ions and other small mols out of cap by filtration into tissue fluid - water potential of blood is more negative then that of tissue fluid (due to presence of plasma proteins) - outward hydrostatic pressure exceeds inward osmotic pull (cause by water potential) and so blood is filtered and fluid leaves blood to form tissue fluid

Question 44

Describe what happens at the venule end (in terms of tissue fluid)

Answer 44

- hydrostatic pressure is lower but water potential remains unchanged (due to loss of fluids and blood moving further away from pumping action of heart) - inwards osmotic pull now exceeds outward hydrostatic pressure - most of filtered water returns to caps from tissue fluid by osmosis

Question 45

What is the importance of the basement membrane in capillaries

Answer 45

Acts as a filter and the gaps increase rate of exchange