There are 3 types of blood vessel:
- Arteries
- Veins
- Capillaries
Arteries
- Arteries carry blood away from the heart.
- They have thick a elastic wall that allows the artery to expand and contract as blood is pushed through under high pressure.
Veins
- Carry blood to the heart.
- Thin inelastic wall as blood is under low pressure.
- They have valves which prevent blood at low pressure from flowing backwards.
Capillaries
- Connect arteries and veins.
- Walls are only 1 cell thick so that gases, nutrients and other chemicals can diffuse easily through them.
- Capillaries surround our cells.