SB7h- Osmoregulation

• What is osmoregulation?

  Controls how much water is lost in urine, so controls how much water is lost in the body. This stops animal cells from swelling or shrinking by osmosis if the water content in the body changes.
• If there is too much water in the body

  1. The body gains water from food or drink
  2. The hypothalamus detects that there is too much water in the body stops sending signals to the pituitary gland
  3. Less ADH is released
  4. Less ADH travels to the kidneys
  5. Tubules reabsorb less water into the blood, so more water stays in the tubules
  6. Urine is a light yellow colour and there is more watery urine
  7. A normal water content in the body is returned
• If there is too little water

  1. The body loses water when breathing out, sweat and in urine
  2. The hypothalamus detects that there is too little water in the body and sends signals to the pituitary gland
  3. The pituitary gland releases a hormone called ADH ( anti-diuretic hormone)
  4. ADH reaches the kidneys and tells the tubules to reabsorb more water into the blood and causes less water to be secreted in urine through selective reabsorption
  5. Urine is a dark yellow colour and there is a small amount of concentrated urine
• What does the urinary system do?

  Maintains water balance, removes excess substances absorbed by food and removes waste products from metabolism such as urea from the breakdown of proteins
• How is urea formed?

  Urea is formed from the breakdown of excess amino acids in the liver. In excess, urea can be toxic
• Steps from the urinary system

  1. The renal arteries carry blood from the body to the kidneys
  2. The kidney removes substances including urea from the blood and makes urine
  3. The renal veins carry cleaned blood back to the body
  4. The urine is carried by ureters from the kidneys to the bladder
  5. The bladder stores urine
  6. A muscle keeps the exit from the bladder closed until we decide to urinate
  7. Urine flows through the urethra to the outside of the body
• Why is osmoregulation important?

  • Our cells lose or gain water by osmosis depending on how much water there is in the body
  • If there is too much water in the body, water will diffuse into cells by osmosis causing them to swell and eventually burst
  • If there is too little water in the body, cells will lose their water and shrink