Blood vessels

3 types of blood vessels

Artery

Vein

Capillary

What arteries do

Carry blood away from heart at high pressure

Artery features

Small lumen

Thick wall

Thick layer of mucus and elastic fibres thag can stretch and withstand pressure

What do veins do

Carry blood to heart at low pressure

Vein features

Large lumen

Relatively thin walls

Valve to prevent back flow

What do capillaries do

Connect arteries ti veins

Carry blood to cells

Allow diffusion of oxygen and carbon dioxide

Features of capillaries

One cell thick wall for short diffusion pathway

Very narrow lumen

What system do humans have

Double circulatory system

Describe the double circulatory system

One transport system carries blood from the heart to the body and back to the heart again

The other carries blood from the heart to the lungs and back again

Why is double circulatory system advantageous

We need lots of oxygen and glucose round the body and double circulatory system allows oxygenated blood to be transported quickly and efficiently. Aswell as that it keeps oxygenated and deoxygenated blood separate