Blood Vessels (Cambridge (CIE) IGCSE Biology)

Blood vessels

• The blood vessels are a system of closed tubes within which blood flows

• Different types of blood vessels transport blood in different directions, and to different parts of the body

Arteries

• These blood vessels carry blood away from the heart at high pressure

• Arteries transport oxygenated

  • The single exception to this is the pulmonary artery

• The walls of arteries are thick and muscular and contain elastic fibres

• Arteries have a narrow lumen

Veins

• These blood vessels carry blood towards the heart at low pressure

• Veins transport deoxygenated blood away from the body

  • The single exception to this is the pulmonary vein

• The walls of veins are thin in comparison to arteries

• Veins have a wide lumen

• Valves in veins prevent blood from flowing backwards

Arteries and veins diagram

Arteries carry blood away from the heart at high pressure, while veins carry blood towards the heart at low pressure

Capillaries

• These blood vessels carry blood to the cells of the tissues

• Capillaries transport oxygenated blood from the arteries to the cells, and deoxygenated blood from the cells to the veins

• The walls of capillaries are one cell thick and contain gaps to allow fluid to leak out

• Capillaries have a very narrow lumen

Capillaries diagram

Capillaries are tiny blood vessels that carry blood to the cells of the body