4.6-regulation of water balance in animals

• Water gain

  • fluid from drink 60%
  • fluid from food 30%
  • metabolic water 10%
• water levels can become too low because of:

  • excessive water loss
  • inadequate intake of fluids
  • abnormal loss of body fluids
• water levels can be too high because of:

  • impaired kidney function that produces insufficient urine
  • excessive amounts of water
  • medical reasons
• effects of water imbalance

  • if water intake is less than the output it’s can lead to a toxic increase in expression and waste product in the blood
• if the water intake is in excess water of water output a person can be hydrated. This involves sweat and drowsiness.
• osmoregulation is the regulation of water balance in the body
• osmolality is an indicator of water level. if it is higher then normal= water level is too low. if it is below the water level is too high.
• the Brian can detect change in osmolality and releases ADH
• the kidney also responds to osmolality by increasing the reabsorption of water and making more urine when its rises
• when water levels are too low:

  1. hypothalamus sends signal to pituitary gland to release ADH
  2. collecting ducts become more permeable
  3. volume of urine produced decreases
  4. the hypothalamus sends a signal of thirst
• wen levels are too high

  1. hypothalamus detects the osmolality which must increase
  2. it signals pituitary for ADH. when not present the kidneys become impermeable to water to make more urine.
  3. thirst is gone
• water balance in fish

  • they have low levels of salt by no drinking
  • dilute urine
  • lose water by their gills
• saltwater fish want MORE salt

  • drink sea water
  • produce minimal urine
  • gills imperative to water