Circulatory System - Blood Vessels

Question 1

What are the three types of blood vessels and what do they do?

Answer 1

Arteries - carry the blood away from the heart.
Capillaries - are involved in the exchange of materials at the tissues.
Veins - carry the blood to the heart.

Question 2

How are arteries designed for their function?

Answer 2

1. The heart pumps the blood out at high pressure so the artery walls are strong and elastic.
2. The walls are thick compared to the size of the hole down the middle (lumen)
3. Contain thick layers of muscle to make them strong, and elastic fibres to allow them to stretch and spring back.

Question 3

How are capillaries designed for their function?

Answer 3

(Arteries branch into capillaries)

1. They are really tiny - too small to see.
2. They carry blood really close to every cell in the body to exchange substances with them.
3. They have permeable walls, so substances can diffuse in and out.
4. They supply food and oxygen and take away waste like carbon dioxide.
5. Their walls are only one cell thick. This increases the rate of diffusion by decreasing the distance over which it occurs.

Question 4

How are veins designed for their function?

Answer 4

(Capillaries eventually join up to form veins).

1. The blood is at a lower pressure in the veins so the walls don’t need to be as thick as artery walls.
2. Have a bigger lumen than arteries to help the blood flow.
3. Have valves to help keep the blood flowing in the right direction.