Biology - Blood vessels

What is an artery?

Carry the blood away from the heart

What is a capillary?

Involved in the exchange of materials at the tissue

What is a vein?

Carry blood to the heart

What is the function of arteries?

• pumps blood out at high pressure so artery walls are strong and elastic

• walls are thick compared to the lumen

• contains thick layers of muscle to make strong and elastic fibres to allow them to stretch and spring back

What is the function of the capillaries?

• arteries branch into capillaries

• capillaries are really tiny (to small to see)

• carry blood really close to every cell in the body to exchange substances with them

• have permeable walls, so substances can diffuse in and out

• supply food and oxygen and take away waste like C02

• walls are usually only one cell thick which increases the rate of diffusion by decreasing the distance over which it occurs.

What is the function of the veins?

• eventually join up to form veins, blood is at the lower pressure in the veins so the walls dont need to be as thick as arteries

• have a bigger lumen that arteries to help the blood flow despite the lower pressure

• have valves to help keep the blood flowing in the right direction

How do you calculate the rate of blood flow?

Rate of blood flow = volume of blood ÷ number of minutes