Tissue fluid

• What is tissue fluid and what is its function?

  • Liquid bathing all cells
  • contains water, glucose, amino acids, fatty acids, ions and oxygen
  • enables delivery of useful molecules to cells and removal of waste
• How is tissue fluid formed?

  • At arteriole end, the smaller diameter results in high hydrostatic pressure
  • small molecules forced out (ultrafiltration)
  • red blood cells / large proteins too big to fit through capillary gaps so remain
• How is tissue fluid reabsorbed?

  • Large molecules remaining in capillary lower its water potential
  • towards venule end there is lower hydrostatic pressure due to loss of liquid
  • water reabsorbed back into capillaries by osmosis
• What is ultrafiltration?

  As blood enters the capillaries from arterioles, the smaller diameter results in a high hydrostatic pressure so water, glucose, amino acids, fatty acids, ions and oxygen are forced out. This is known as ultrafiltration.
• What is the purpose of tissue fluid?

  The purpose is to enable the delivery of useful molecules to cells and to move waste into the bloodstream so it can be removed from the body.
• Describe the role of the lymphatic system in the reabsorption of tissue fluid.

  • Not all liquid will be reabsorbed by osmosis as equilibrium will be reached
  • excess tissue fluid (lymph) is absorbed into lymphatic system and drains back into bloodstream and deposited near heart