参考答案:
In arteries the blood flow is in pulses which expand the wall of the artery.
The elastic tissue allows for the expansion and contraction of the artery wall.
The elastic tissue contracts the artery wall after expansion.
The contraction maintains the high pressure needed for fast flow rates.
The muscular tissue is smooth muscle.
Smooth muscle is stretched by the pulse of blood.
Smooth muscle contracts in response to being stretched.
The contraction of smooth muscle maintains blood pressure and flow in the artery.
In smaller muscular arteries (and arterioles) smooth muscle can restrict blood flow.
(Award 1 mark for each point, up to a maximum of 6 marks)
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