Osmoregulation

• Osmoregulation

  • the control of water potential and solute concentration level in the blood to maintain a constant water potential in the body
  • the amount of water in the blood plasma is controlled by antidiuretic hormone
• Importance of maintaining water potential of blood


  • water potential of the blood has to be kept relatively constant
  • If blood plasma becomes too diluted, water enters the cell by osmosis, tissue cells and blood cells swell and burst
  • If blood plasma is too concentrated, water moves out of the cells by osmosis, tissue cells and blood cells shrinks and becomes crenated, it can no longer carry out metabolic processes properly
• How kidneys regulate the water potential of blood - low wp

  1. when water is lost, water potential of blood plasma decreases, which stimulates the hypothalamus in the brain
  2. the pituitary gland releases more ADH into the bloodstream
  3. cell in the walls of the collecting ducts become more permeable to water. More water reabsorbed from the collecting duct into the blood capillaries
  4. smaller volume of urine is produced and the urine is more concentrated
  5. water potential of plasma increases back to normal
• How kidneys regulate the water potential of blood - high wp


  1. when water is taken in, water potential of blood plasma increases, which stimulates the hypothalamus in the brain
  2. the pituitary gland releases less ADH into the bloodstream
  3. cell in the walls of the collecting ducts become less permeable to water. less water reabsorbed from the collecting duct into the blood capillaries
  4. larger volume of urine is produced and the urine is more diluted
  5. water potential of plasma decreases back to normal