Blood vessels and their function

Question 1

What are the 4 different types of blood vessels?

Answer 1

Arteries, arterioles, capillaries and veins

Question 2

What is the function of an artery?

Answer 2

To transport blood rapidly under high pressure from the heart to tissues.

Question 3

What is the function of an arteriole?

Answer 3

To carry blood, under lower pressure than the arteries, from arteries to capillaries.

Question 4

What is the function of a vein?

Answer 4

Veins transport blood, slowly under pressure, from the capillaries in tissues to the heart.

Question 5

What is the function of capillaries?

Answer 5

To exchange metabolic material, such as oxygen and carbon dioxide, between the blood and cells of the body.

Question 6

What is the structure of an artery? How is it related to its structure.

Answer 6

Thick muscle layer - smaller arteries constrict and dilate to control vol of blood pushing them through.
Relatively thick elastic layer - bp needs to be kept high if the blood is to reach anywhere.
Thick walls - stops vessels from bursting under pressure.
No valves - high pressure so no back-flow occurs.

Question 7

What is the structure of an arteriole? How is it related to its function?

Answer 7

Relatively thinner muscle layer than arteries

Elastic layer is thinner than in arteries - bp is lower.

Question 8

What is the structure of a vein? How is it related to its function?

Answer 8

Thin muscle layer - Carry blood away from tissues.
Thin elastic layer - low bp will not cause veins to burst.
Valves - Ensure that blood does not flow backwards due to the low bp.

Question 9

What is the structure of a capillary? How is it related to its function?

Answer 9

Walls are 1 cell thick - making them extremely thin so short diffusion distance.
Numerous and highly branched - provide a large SA for exchange.
Narrow diameter
Narrow lumen - RBCs are squeezed flat against the side of a capillary bringing them closer to the cells reducing diffusion distance.
Spaces between the lining (endothelial) cells that allow WBCs to escape to deal with an infection.

Question 10

What is the basic structure of all vessels? How does this help them function?

Answer 10

Tough fibrous outer layer - resist pressure changes from both outside and within.
Muscle layer - can contract so controls the flow of blood.
Elastic layer - helps to maintain bp by stretching and recoiling.
Thin inner (endothelial) layer - smooth to reduce friction and thin to allow diffusion.
Lumen - central cavity through which blood flows.