blood vessels

Question 1

In a healthy person, blood moves in one direction as it passes through the heart. Give two ways in which this is achieved

Answer 1

Pressure gradient / moves from high to low pressure;

2. Valves stop backflow;

Question 2

Some babies are born with a hole between the right and the left ventricles.

These babies are unable to get enough oxygen to their tissues.

Suggest why.

Answer 2

Blood flows from left ventricle to right ventricle/ mixing of oxygenated and deoxygenated blood;

2. Lower volume of (oxygenated) blood leaves left ventricle/flows into aorta/C

OR

Lower pressure in blood leaving left ventricle/flowing into aorta/C

OR

Less oxygen in blood leaving left ventricle/aorta/C;

Question 3

The rise and fall in blood pressure in the aorta is greater than in the small arteries.Suggest why.

Answer 3

Aorta)

1. (is) close / directly linked to the heart / ventricle / pressure is higher / is very high;
2. (Aorta has) elastic tissue;

Accept elasticity

Ignore reference to muscle

3. (Aorta has) stretch / recoil.

Question 4

) In one cardiac cycle, the volume of blood flowing out of the heart along the pulmonary artery is the same as the volume of blood returning along the pulmonary vein. Explain why the volumes are the same although the speed of flow in the artery is greater than in the vein.

Answer 4

larger / wider lumen so greater volume carried;

Question 5

Arteries and arterioles take blood away from the heart.

Explain how the structures of the walls of arteries and arterioles are related to their functions.

Answer 5

Elastic tissue stretches under pressure / when heart beats then recoils / springs back;

2. Evens out pressure / flow;

2 Do accept controls

Muscle

3. Muscle contracts to reduce diameter of lumen / vasoconstriction / constricts vessel;
4. Changes flow / pressure;

Epithelium

5. Epithelium smooth;
6. Reduces friction / blood clots / less resistance;

Question 6

Explain the importance of elastic fibres in the wall of the aorta.

Answer 6

Stretches / ’expands’ under high pressure / when ventricle
contracts / systole and recoils / ’springs back’ under low pressure / when ventricle relaxes / diastole;

Q References to aorta contracting or relaxing negates marks for stretch and recoil.

Smooths blood flow / maintains blood pressure / reduces pressure surges;

Question 7

The rate of blood flow decreases from the aorta to the capillaries. Use information from the graph to explain why.

________________________ capillary has a bigger cross sectional area

Answer 7

Large / increase in (total) cross sectional area / friction / resistance;

Question 8

Efficient exchange of substances in the capillaries is linked to the rate of blood flow. Explain how.

Answer 8

(More) time for exchange of substances;

Question 9

You could use the graph to predict the effect of this treatment on the increase in haemoglobin content of an adult after 40 days. Explain how.

Answer 9

Use line of best fit;

1

Extrapolate / extend line (and read from graph);

Question 10

Pernicious anaemia is another type of anaemia. One method of identifying pernicious anaemia is to measure the diameter of the red blood cells in a sample of blood that has been diluted with an isotonic salt solution. Explain why an isotonic salt solution is used to dilute the blood sample.

Answer 10

i) Has same water potential;

Allow converse for effect of using distilled water or a concentrated solution.

1

No (net) water movement / osmosis;

1

Cells will not swell / burst / change size