Structure & Function of Blood Vessels

How Structure of Blood Vessels is Adapted to their Function

How Structure of Blood Vessels is Adapted to their Function

Arteries

• Have thick, muscular walls containing elastic fibres to withstand the high pressure of blood and maintain the blood pressure as it recoils after the blood has passed through

• Have a narrow lumen to maintain high pressure

Veins

• Have a wide lumen as blood pressure is low

• Contain valves to prevent the backflow of blood as it is under low pressure

Capillaries

• Have walls that are one cell thick so that substances can easily diffuse in and out of them

• Have ‘leaky’ walls so that blood plasma can leak out and form tissue fluid surrounding the neighbouring cells

• Are narrow so that red blood cells have to touch the sides as they pass through in single-fil

  • This reduces the diffusion distance for gas exchange as the cells bind/release oxygen molecules

Adaptations of Blood Vessels Diagram

Adaptations of blood vessels

Arterioles and venules

• As arteries divide more as they get further away from the heart, they get narrower

• The narrow vessels that connect arteries to capillaries are called arterioles

• Veins also get narrower the further away they are from the heart

• The narrow vessels that connect capillaries to veins are called venules

The Blood Vessel Network Diagram

The blood vessel network