Tissue Fluid

• What is the main function of an artery?

  To carry blood away from the heart
• How does the structure of an artery relate to its function?

  Thick walls withstand high blood pressure
• What are the key structural features of arteries?

  • Thick collagen layer for high pressure
  • Elastic tissue for stretching and recoiling
  • Folded inner endothelial layer for stretching
  • Smooth muscle for constriction and dilation
  • Narrow lumen to maintain pressure
• What is the hydrostatic pressure at the venule end of the capillary?

  1.3 kPa
• What happens to tissue fluid at the venule end of the capillary?

  Fluid moves into the capillary from tissues
• What is the oncotic pressure at the venule end of the capillary?

  -1.2 kPa
• What is the role of hydrostatic pressure at the venule end?

  It prevents inward movement of liquids
• What happens to excess tissue fluid not reabsorbed into capillaries?

  It enters lymphatic vessels
• Where does lymph drain back into the bloodstream?

  Near the heart via two ducts
• What is the primary duct for lymph drainage?

  Thoracic duct
• What causes lymphoedema?

  Blockage in the lymphatic system
• What is tissue fluid composed of?

  Water, glucose, amino acids, salts, oxygen
• What is the process of tissue fluid formation at the arteriole end?

  High hydrostatic pressure forces fluid out
• What prevents all water from moving back into the blood?

  Hydrostatic pressure and equilibrium
• What is ultrafiltration in the context of capillaries?

  Forcing small molecules out of capillaries
• What is the hydrostatic pressure at the arteriole end of the capillary?

  5.2 kPa
• What is the oncotic pressure at the arteriole end of the capillary?

  -2.9 kPa
• What is the effect of hydrostatic pressure compared to oncotic pressure at the arteriole end?

  Hydrostatic pressure has a greater effect
• What are the factors opposing hydrostatic pressure at the arteriole end?

  • Hydrostatic pressure of tissue fluid
  • Lower water potential of blood due to proteins
• What is the role of smooth muscle in lymphatic vessels?

  Allows constriction and dilation
• What is the role of valves in lymphatic vessels?

  Prevent backflow of lymph
• What is the effect of skeletal muscle action on lymph movement?

  It aids in pushing lymph through vessels
• What is the effect of respiratory movements on lymph movement?

  It helps to facilitate lymph flow
• What is the relationship between blood pressure and lymphatic drainage?

  Lymph drains where blood pressure is lowest
• What are the main components of tissue fluid formation and return?

  • Formation at arteriole end: high hydrostatic pressure
  • Return at venule end: osmotic pressure predominates
  • Role of lymphatic system in excess fluid removal