ADH

• Homeostasis


  Keeping the body's internal environment within narrow limits, not too high or too low, just right
• ADH (Antidiuretic hormone)


  Hormone that regulates the amount of water in the bloodstream
• ADH


  • Targets the kidney, specifically the nephrons
  • Causes the body to urinate less
• How ADH regulates water in the body


  1. Stimulus (change in osmolarity)

  2. Hypothalamus detects change

  3. Hypothalamus signals pituitary gland

  4. Pituitary gland secretes more/less ADH

  5. ADH acts on distal convoluted tubule and collecting duct

  6. Makes them more/less permeable to water

  7. More/less water reabsorbed into bloodstream

  8. Small/large concentrated/dilute urine produced

  9. Returns to normal water levels
• ADH is always present in the body, it is just secreted more or less depending on the situation
• Osmolarity


  Measure of how much water and solutes (like salt) are in the blood
• Hypothalamus


  Region of the brain responsible for maintaining homeostasis
• Pituitary gland


  Master gland that secretes hormones, including ADH
• Distal convoluted tubule and collecting duct


  Regions of the nephron where ADH acts to regulate water
• The answer for how ADH regulates water is similar whether it's a hot day, cold day, after exercise, etc. The key differences are whether osmolarity increases or decreases, and whether ADH secretion increases or decreases.
• On a hot day SELD


  sweating

  exercising

  loss of water

  dehydration
• What happens on a hot day

  Increase in osmolarity➡️hypothalamus(maintains homeostasis)➡️pituitary gland➡️ADH secreted more➡️ADH sent to DCT + collecting duct(now it’s more permeable)➡️more water is reabsorbed➡️small concentrated amount of urine is produced➡️return to norm
• On a cold day RID

  Resting

  drinking lots of water

  inactive