Hormones and osmoregulation

• What happens when the body detects a lower water potential than normal?

  • Osmoreceptors send a signal to the hypothalamus to release antidiuretic hormone (ADH)
  • ADH passes to pituitary gland
  • ADH goes to kidney where it increases the permeability of the distal convoluted tubule and the collecting duct
  • ADH activates phosphorylase, which causes vesicles containing aquaporins to fuse with the cell membrane
  • So amount of water channels are increased, making it more permeable to water
• What detects a change In water potential?

  Osmoreceptors
• Where are osmoreceptors located?

  Hypothalamus
• What hormone is released by the hypothalamus?

  Antidiuretic hormone
• Where does ADH pass to?

  Pituitary gland and then the kidney
• What does ADH increase the permeability of?

  Distal convoluted tubule

  Collecting duct
• What enzyme is activated by ADH?

  Phosphorylase
• What does phosphorylase do?

  Casuses vesicles to fuse with the cell membrane
• What do the vesicles that fuse to the cell membrane contain?

  Aquaporins
• What do aquaporins do?


  Increase the amount of water channels, so the membrane becomes more permeable to water
• What does ADH increase the permeability of to urea?

  Collecting duct
• What happens when water potential is too high?

  • Osmoreceptors detect an increase of water potential so tell the pituitary gland to reduce ADH
  • Collecting ducts reduce their permeability
  • Less water is absorbed into blood
  • More dilute urine is is produced