Capillaries

Capillaries

Structure and Function

• The function of capillaries is exchange materials between cells in tissues and blood travelling at low pressure. 
  • arteries split into arterioles which in turn split into capillaries, decreasing arterial pressure as total vessel volume is increased.
  • the branching of arteries into capillaries ensures blood is moving slowly and all cells are located near a blood supply.
  • after material exchange - capillaries pool into venules and eventually veins.

• Specialised structure to allow for efficient material exchange:
  • very smal diameter ( ~5µm wide ) - allows for passage of only one RBC at a time = optimal exchange.
  • capillary wall made up of a single layer of cells - minimises diffusion distance for permeable materials.
  • surrounded by a…