Topic 3- blood vessels

Question 1

What is the function of aerteries?

Answer 1

transport blood away from the heart (usually at high pressure)

Question 2

What is the function of veins?

Answer 2

transport blood to the heart (usually at low pressure)

Question 3

What is the function of arterioles?

Answer 3

arteries branch into narrower blood vessels called arterioles which transport blood into capillaries

Question 4

Arteries must be able to withstand high pressures generated by the contracting heart, and maintain these pressures when the heart is relaxed, what adaptations do they have to ensure this?

Answer 4

-Arteries must be able to withstand high pressures generated by the contracting heart, and maintain these pressures when the heart is relaxed
- elastic fibres allow the artery wall to expand around blood surging through at high pressure when the heart contracts, these fibres then recoil when the heart relaxes
-arrow lumen maintains high blood pressure

Question 5

Veins receive blood that has passed through capillary networks; blood is at very low pressure and must be returned to the heart, give some adaptations?

Answer 5

wall of the vein is relatively thin with thinner layers of collagen, smooth muscle and elastic fibres

The lumen of the vein is much larger than that of an artery

Veins contain valves that prevent the backflow of blood, helping return blood to the heart

Question 6

Arterioles can contract and partially cut off blood flow to specific organs-
Eg. During exercise blood flow to the stomach and intestine is reduced which allows for more blood to reach the muscles- what adaptations do they have?

Answer 6

arterioles have a lower proportion of elastic fibres and a large number of muscle cells

The presence of muscle cells allows them to contract and close their lumen to stop blood flow