ADH

• OSMOREGULATION

  • maintaining water & salt concentrations (osmotic balance) across membranes in body
  • homeostasis
  • cytoplasm and blood plasma mainly water
  • Maintaining water levels to prevent harmful changes to cells bc of osmosis
  • lose or gain too much water = dont function efficiently:

  1. Too much water in blood: cells swelling as water moves in, this has a diluting effect and can lead to cell lysis (bursting)
  2. Too little water in blood (or too high an ion concentration): cells lose water, dehydrating effect -> cell death
• label

  A) hypertonic

  B) isotonic

  C) hypotonic

  D) higher

  E) out

  F) crenation

  G) equal

  H) lyse

  
• WATER

  • There are two sources of water in the body:

  1. Water produced as a result of aerobic respiration
  2. Water in the diet

  • Water is lost from the body in the following ways:

  1. Via the lungs during exhalation (breathing out)
  2. Lost from the skin as sweat to regulate body temperature (along side mineral ions and urea)
  3. Water lost through the lungs or skin cannot be controlled, but the volume of water lost in the production of urine can be controlled by the kidneys
• ADH

  • Water reabsorption along nephron tubules
  • exmple of negative feedback: If water content of blood too high, less water reabsorbed. low = more water reabsorbed
  • controlledby hormone ADH releasedby pituitary gland
  • amt released depends amtof water kidneys need to reabsorb frm filtrate
  • ADH affects permeability of tubules to water
  • water% too high:

  1. release less ADH -> less water reabsorbed in collecting ducts by osmosis (collecting ducts bcme less permeable to water)
  2. kidneys produce large vol dilute urine

  • low:

  1. more ADH & water reabsorbed (more permeable)
  2. small vol concentrated urine
• label

  A) hypothalamus

  B) water level

  C) pituitary gland

  D) adh

  E) more

  F) reabsorbed

  G) less

  H) urine

  I) blood water

  J) less

  K) less

  L) more

  M) urine

  N) negative feedback