tissue fluid formation

• Tissue fluid


  Liquid which surrounds the cells in the body
• Tissue fluid


  • Contains water, glucose, amino acids, fatty acids, dissolved ions and minerals, oxygen
  • Surrounds tissues so cells can gain access to essential molecules
• Formation of tissue fluid

  1. Capillaries are one cell thick with tiny gaps

  2. Arterioles attached to arteries have high blood pressure

  3. High pressure causes ultrafiltration - water and small molecules forced out of capillaries

  4. Large molecules like red blood cells and proteins remain in blood
• Molecules forced out of capillaries

  • Water
  • Dissolved minerals and salts
  • Glucose
  • Small proteins
  • Individual amino acids
  • Fatty acids
  • Oxygen
• Molecules too large to be forced out

  • Red blood cells
  • Platelets
  • Large proteins
• Reabsorption of tissue fluid

  1. At venule end of capillary bed, blood has low pressure and negative water potential

  2. Water moves back into capillaries by osmosis

  3. Dissolved waste like carbon dioxide and urea also reabsorbed

  4. Remaining fluid absorbed into lymphatic system
• Tissue fluid is not red in colour as it does not contain red blood cells
• Equilibrium is eventually reached where osmosis can no longer reabsorb all the tissue fluid</b>