6a/b - Mass Transport in Animals

Question 1

Define ‘oxygenated blood’

Answer 1

high in oxygen and low in carbon dioxide

Question 2

Define ‘deoxygenated blood’

Answer 2

Low in oxygen and high in carbon dioxide

Question 3

Describe diastole

Answer 3

The heart relaxes, atria fill with blood from vena cava and pulmonary veins.
Semi - lunar valves closed as pressure higher in arteries than ventricles

Question 4

Describe atrial systole

Answer 4

Blood fills the atria from vena cava and pulmonary vein.
Atrial muscles contract causing pressure to increase in ventricles.
The pressure forces av valves open, blood flows into ventricles

Question 5

Describe ventricular systole

Answer 5

Ventricle muscles contract causing volume in vs to decrease and pressure to increase.
Causes av valces to close and semi-lunar to open.
Blood flows into aorta and pulmonary vein

Question 6

Define stroke volume

Answer 6

The volume of blood pumped out of one ventricle during each contraction

Question 7

Define cardiac output

Answer 7

Total volume pumped from one ventricle per minute

Question 8

How do you calculate the cardiac output

Answer 8

CA = Stroke volume x Heart rate

Question 9

Describe the structure of arteries

Answer 9

Very thick walls
Walls have an inner coar of a single layer of endothelium
Thick middle coat of smooth muscle and elastic fibres
Outer coat of collagen fibres

Question 10

Describe the structure of veins

Answer 10

Very thin walls
Have valves
Thin middle coat of smooth muscle and elastic fibres
Outer coat of collagen fibres

Question 11

Describe the structure of capillaries

Answer 11

Tiny pores so highly permeable
Single layer of endothelium
Large SA:Vol ratio
Short diffusion pathway
Slow rate of blood so more time for diffusional exchange

Question 12

At the arteriole end of the capillary the hydrostatic pressure of the blood is high. What causes this?

Answer 12

The contraction of the left ventricle in the ventricular systole

Question 13

How is tissue fluid formed and reabsorbed?

Answer 13

The high blood pressure forces out water, salts (small solutes) and nutrients.
The soluble plasma proteins in blood, which reduce the water potential of the blood. This creates a water potential gradient, which exerts a pulling force, opposing loss of this fluid

Question 14

Why is water drawn back into the capillaries at the venule end?

Answer 14

Water potential of the blood at end of capillary is low, tissue fluid is high. This creates a large inward osmotic pull which is greater than blood pressure. Water drawn back in by osmosis down a wp gradient

Question 15

How is tissue fluid drained away from cells?

Answer 15

By lymph vessels and is returned to the circulation near the heart

Question 16

Describe the function of haemoglobin

Answer 16

Has high affinity for oxygen
Loads oxygen when O2 conc. high
Dissociates from (unloads) O2 where O2 conc. low

Question 17

Where in the body would O2 conc. be:

a) high
b) low

Answer 17

a) lungs

b) respiring tissue

Question 18

Define the term ‘conjugated’

Answer 18

The protein is bound to a non-protein group (e.g.iron)

Question 19

Define ‘affinity’

Answer 19

The binding potential of molecules

Question 20

Define ‘cooperative binding’

Answer 20

As more O2 molecules bind to haemoglobin the tertiary structure and shape of haemoglobin changes, making it easier for next O2 to bind - increases affinity

Question 21

What shape is the oxygen dissociation graph?

Answer 21

Sigmoidal

Question 22

What happens to the dissociation graph when there is an increase in temperature, acidity and CO2 conc.?

Answer 22

Shifts right - Bohr shift

Question 23

When is it likely that there will be an increase in temperature, acidity and CO2 conc.?

Answer 23

During exercise - faster cellular respiration, more heat and CO2 produces. CO2 dissolves to form a weak acid

Question 24

What happens to the affinity of haemoglobin when the curve shifts right?

Answer 24

Affinity for O2 decreases so unloading of O2 to tissues is increased

Question 25

What happens to the affinity of haemoglobin when the curve shifts left?

Answer 25

Affinity for O2 increased so unloading of O2 to tissues is decreased