Module 3 - Mass transport in animals

Question 1

What is the meaning of partial pressure for oxygen

Answer 1

A measure of the concentration of oxygen

Question 2

What are the conditions for oxygen loading and unloading from haemoglobin

Answer 2

At a high partial pressure, oxygen loads onto haemoglobin and at a low partial pressure. Oxygen unloads to oxyhaemoglobin.

Question 3

Describe the dissocation curve

Answer 3

When the first molecule of oxygen binds to haemoglobin, then the shape of haemoglobin changes to make it easier for oxygen to bind to. As the haemoglobin becomes more saturated, the graph plateaus. This describes the ‘s’ shape of the curve.

Question 4

Describe the Bohr effect

Answer 4

Oxygen unloads oxygen more readily when there is a high partial pressure of C02. This means that when cells respire, they produce carbon dioxide as a waste product. This increases CO2 which means oxygen unloads more from oxyhaemoglobin. This causes the dissociation curve to shift right.

Question 5

What affinity for oxygen will an organism have that lives in an area of low concentration of oxygen?

Answer 5

The organism will have a high affinity for oxygen so the dissociation curve is to the left of human dissociation curves

Question 6

What affinity for oxygen will an organism have that lives in an area of high concentration?

Answer 6

The organism has a low affinity for oxygen so, the dissociation curve is to the right of human dissociation curves.

Question 7

What is the haemoglobin reversible formula?

Answer 7

Hb + 402 —– Hb08

Question 8

Give 3 properties of haemoglobin?

Answer 8

1) Made up of 4 polypeptide chains
2) Each chain has a haem group with an iron ion
3) Can carry 4 oxygen molecules

Question 9

What are the 2 main arteries in the heart? Where do they flow and what do they carry?

Answer 9

Aorta and pulmonary artery.
The aorta carries oxygenated blood to the body
The pulmonary artery carries deoxygenated blood to the lungs

Question 10

What are the 2 main veins in the heart. Where do they flow and what do they carry?

Answer 10

Vena cava and Pulmonary vein
The vena cava carries deoxygenated blood back to the heart from the body
The pulmonary vein carries oxygenated blood to the heart from the lungs

Question 11

What is the artery and vein called that goes and comes from the kidneys?

Answer 11

The renal artery carries oxygenated blood to the kidneys and the renal vein carries deoxygenated blood from the kidneys

Question 12

What is the artery and vein called that goes and comes from the liver?

Answer 12

The hepatic artery carried oxygenated blood and goes to the liver and the hepatic vein carries deoxygenate blood and goes to the liver

Question 13

Describe 5 features within a vein

Answer 13

• Wide lumen
• valves to prevent backflow as blood is carried at a low pressure
• Little muscle tissue
• Little elastin tissue
• High resistance

Question 14

Describe 5 features within an artery

Answer 14

• Folded endothelium with a small lumen
• Thick muscle layer
• Thick elastin layer
• High pressure blood flow
• Low resistance

Question 15

Describe 3 features within a capillary

Answer 15

• One cell thick wall (short diffusion pathway)
• Small lumen (only allows one blood cell at a time)
• Forms a large network to increase surface area for gas exchange

Question 16

Briefly explain the formation of tissue fluid.

Answer 16

1) Hydrostatic pressure inside the capillaries is higher than inside the spaces between cells.
2) Forces fluid out of the capillaries ad around the cells forming tissue fluid
3) As fluid is moved out, the hydrostatic pressure inside the capillaries fall so the hydrostatic pressure in the venule end falls.
4) This then causes the water potential at the venule end to fall so, the water moves out of the tissue fluid into the capillaries via osmosis
5) Excess tissue fluid is drained into the lymphatic system

Question 17

3 marks

Explain why high blood pressure leads to an accumulation of tissue fluid

Answer 17

1. High blood pressure= higher hydrostatic pressure
2. Increases outward pressure from arteriole end of capillary
3. So more tissue fluid formed/ less tissue fluid reabsorbed

Question 18

Why does the left ventricle have thicker muscle than the right ventricle?

Answer 18

The left ventricle has more muscle because the ventricle has to be able to contract the blood further at a higher pressure given. That blood needs to travel to the rest of the body and not juts the lungs.

Question 19

3 marks

Explain why the rise and fall in blood pressure in the aorta is greater than in the small arteries

Answer 19

Aorta has higher pressure/ close to the heart
Aorta has elastic tissue
Aorta stretches when pressure is hugher then recoils

Question 20

What are the names of the 2 types of valves within a heart?

Answer 20

The atrioventricular valves (bicuspid in left tricuspid in right) between atria and ventricles.
The semi lunar valves which are between ventricles and arteries.

Question 21

What occurs in the heart when the atria contract?

Answer 21

When the atria contract, the volume of the atria decreases but, the pressure inside the ventricles increases. This causes the atrioventricular valves to open and blood is forced into both ventricles.

Question 22

What occurs in the heart when the ventricles contract?

Answer 22

When the ventricles contract, the volume of the ventricles decreases but, the pressure inside the ventricles increases. This causes the Atrioventricular valves to be forced shut but the pressure inside the ventricles is higher than the arteries so, the SL valves are forces open.

Question 23

What occurs in the heart when the ventricles and atria relax?

Answer 23

When the pressure inside the pulmonary vein and vena cava increases, this causes the atria to fill with blood which causes the pressure inside the atria to begin to rise. The atria then contract and the cardiac cycle repeats.

Question 24

What happens to pressure in atria and ventricles when the atria contract?

Answer 24

The pressure inside the atria increases but the pressure inside the ventricles also increases but not by as much as the atria. This is due to the passive filling of blood from the atria, into the ventricles

Question 25

What happens to the pressure in the atria and ventricles when the ventricles contract?

Answer 25

The pressure in the ventricles rapidly increase and the pressure in the atria decreases.

Question 26

What happens in the atria and the ventricles when the atria and ventricles relax?

Answer 26

The atrial pressure rises as they fill with blood. The ventricular pressure falls as they relax. Eventually the pressure inside the ventricles increases as the pressure begins to increase.

Question 27

5 marks

Explain how the heart muscle and the heart valves maintain a one way flow of blood from the left atrium to the aorta

Answer 27

1. Atrium has higher pressure than ventricle due to contraction causing AV valves to open
2. Ventricle has higher pressure than atrium due to contraction causing AV valves to close
3. Ventricle has higher pressure than aorta causing semi lunar vavlve to open
4. Higher pressure in aorta than ventricle as heart relaxes causing semi lunar vavle to close
5. contraction cause increase in pressure

Question 28

Briefly explain an atheroma formation

Answer 28

If the endothelium of an artery wall becomes damaged, then white blood cells and lipids clump to form a fatty areas.
Overtime, they build up to form fibrous plaques. These are called atheroma. When these build up over time, they can restrict blood flow to the heart, increasing blood pressure.

Question 29

What are the 2 types of diseases that affect the arteries?

Answer 29

Aneurysm and thrombosis.

Question 30

What is aneurysm?

Answer 30

Atheroma’s increase blood pressure. This means when blood comes past arteries at a high pressure. It may push these atheroma’s through the inner lining through to the outer elastin tissue causing swelling

Question 31

What is thrombosis?

Answer 31

When damage is caused by an atheroma, platelets and fibrin form around damaged area. This then causes a blockage of an artery and means the artery can become dislodged.

Question 32

What is myocardial infarction

Answer 32

A heart attack which can be caused by a blockage in the coronary artery.

Question 33

What are the 3 main risk factors of cardiovascular disease?

Answer 33

• Smoking - Nicotine increases blood pressure and carbon monoxide binds to haemoglobin and reduces oxygen binding
• High blood pressure - More damage to artery walls
• High blood cholesterol - one of the main constitutes to fatty deposits forming atheromas.

Question 34

What is the formula for cardiac output?

Answer 34

Cardiac output = stroke volume x heart rate

Question 35

Why is it important that blood maintains a constant pH?

Answer 35

If blood was to change pH, then haemoglobin - for example - will see a change in its tertiary structure. This will then cause less oxygen to be able to bind to haemoglobin.

Question 36

Why is water potential more negative at the venule end?

Answer 36

When fluid moves out, plasma proteins cannot leave the capillaries as they are too large. This causes the concentration of plasma proteins to increase inside the capillaries.