GCSE Biology (AQA)

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Water Balance

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Homeostasis and Response Hormonal Coordination in Humans

Water Balance

2:40 Role of the Kidneys in Homeostasis
Spec 4.5.3.3
Previous Reproductive Hormones Next Nitrogen Balance
  • Water levels in the body decrease through exhalation, sweating, and urination.
  • Urine is produced in the kidneys and excreted from the bladder.
  • Water levels increase by eating and drinking.
  • Sweat excretes water, sodium, chloride, and urea.
  • The primary function of sweat is to cool the body, not to remove excess water.
  • Kidneys regulate water levels by removing excess water from the blood.
  • Urination removes excess ions, urea, and water, contrasting with water loss through breathing and sweating.
  • Changing water levels affect cells through osmotic changes, impacting the diffusion of water across cell membranes.
  • Cells in low water environments will shrivel as water moves from a higher concentration inside to a lower concentration outside.
  • In healthy water levels, there is no net movement of water into or out of cells.
  • Cells in high water environments can swell or burst as water moves from a higher concentration outside to a lower concentration inside.
  • Proper cell function is compromised if cells gain or lose too much water by osmosis.
  • Maintaining healthy water levels is crucial for bodily functions.

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