Maintaining water balance in the body

• What are the two important areas inside the brain related to water regulation?

  The hypothalamus and the pituitary gland
• What role does the hypothalamus play in the body?

  It detects changes in the blood plasma
• What is the function of the pituitary gland?

  It regulates the release of anti-diuretic hormone (ADH)
• How does the concentration of water in the blood plasma affect ADH release?

  Different amounts of ADH are released according to the concentration of water
• When is ADH released by the pituitary gland?

  When the blood is too concentrated
• What effect does ADH have on kidney tubules?

  It makes them more permeable
• What happens during selective reabsorption in the kidneys?

  More water is reabsorbed back into the blood
• What occurs if a person consumes a large volume of water?

  Less ADH will be released, resulting in a larger volume of dilute urine
• What happens if a person sweats a lot but does not drink enough water?

  More ADH will be released, resulting in concentrated urine
• What are the stages of urine formation in the kidneys?


  1. Filtration: Blood is filtered in the nephron, small molecules pass into the tubule.
  2. Selective reabsorption: Essential molecules like glucose, water, and ions are reabsorbed.
  3. Formation of urine: Non-reabsorbed molecules (urea, excess water, ions) continue to form urine.
• What is the role of high pressure in the nephron during filtration?

  It aids the ultrafiltration of the blood
• What small molecules are filtered out during the filtration stage?

  Urea, water, ions, and glucose
• Why do large molecules like blood proteins remain in the blood during filtration?

  They are too big to fit through the capillary wall
• What is the purpose of selective reabsorption in the kidneys?


  To reabsorb needed molecules while allowing waste to pass out in urine
• Which molecules are fully reabsorbed during selective reabsorption?

  All of the glucose
• What is the outcome for water and ions during selective reabsorption?

  As much water and ions as needed are reabsorbed
• What happens to molecules not selectively reabsorbed?

  They continue along the nephron tubule as urine
• What is the final destination of urine formed in the kidneys?

  It passes down to the bladder to be stored
• What functions do the kidneys perform in relation to blood plasma?

  • Regulate water balance
  • Maintain ion balance
  • Keep urea levels low
• Can large substances be filtered by the kidneys


  No because they are too large to be filtered

  only small substances like urea water and glucose are filtered
• why are proteins broken down by deamination


  to form ammonia but it is toxic to the body so it quickly converts it to urea a waste product