blood vessels

Question 1

Some drugs used to reduce high ventricular blood pressure cause widening of blood vessels.

Suggest how widening of blood vessels can reduce ventricular blood pressure.

Answer 1

Larger lumen/volume (of blood vessels);

Accept: more ‘space’ or more ‘room’ (in blood vessels).

Accept: more blood flow (in blood vessels).

Accept: reduces stroke volume or less blood in ventricle.

2. Reduces (blood) pressure (in blood vessels);
3. Less friction/resistance (in blood vessels);

Question 2

Seals are mammals. They spend much of the time in water but have lungs and breathe air. When a seal is resting at the surface of the water, the blood flow to each gram of swimming muscles is 0.21 cm3 per minute. When it is swimming under water, the blood flow to different organs changes. The flow to the swimming muscles is then 0.05 cm3 per gram per minute.

(a) Describe the part played by arterioles in redistributing blood to different organs.

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(2)

(b) (i) Describe how the change in blood flow to the muscles of a seal differs from the change in blood flow to human muscles as activity increases.

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(1)

(ii) Suggest the advantage to the seal of the change in blood flow to the muscles.

Answer 2

The muscle in the wall / sphincter contracts;

Accept converse

Reducing blood flow / narrowing / closing arteriole;

The muscle to which the candidate is referring must be clearly in the wall of the arteriole.

2

(b) (i) Blood flow increased in humans / reduced in seals;

1

(ii) Less oxygen / blood taken to muscles;

None is incorrect

(More) oxygen available for organs / brain;
Can stay under water longer (without breathing);

Question 3

Explain why a vein may be described as an organ.

Answer 3

made of (different) tissues / specified tissues;

Question 4

Use information from the table to suggest the thickness of a capillary wall.
Give the reason for your answer.

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Answer 4

20 µm as it consists of endothelium only / does not contain muscle,
connective tissues and elastic tissue;E

Question 5

Explain how the elastic tissue in the wall helps to even out the pressure of blood flowing through the artery.

Answer 5

stretches as a result of high pressure / surge of blood;
then recoils;