Kidneys

• what is osmosis?

  movement of water from a dilute to a concentrated solution through a partially permeable membrane
• if the body cells gain or lose too much water by osmosis, they don't work effciently
• if the blood becomes too concentrated, the water moves out of the cells by osmosis (VISEVERSA)
• 3 ways the body loses water?

  1. Urination 2. Sweating 3. Breathing
• how does the kidneys remove urea?

  1. blood enters the kidney through the artery = blood contains urea
  2. kidney removes this urea and excess ions and water
  3. these leave the kidney as urine and this is stored in the bladder
  4. blood leaves the kidney thru a vein = blood contains no urea
• how does the kidneys adjust the level of molecules in the blood?

  1. blood passes through the capillaries = small molecules ( urea, ions, h20, glucose) are flitered out of the blood
  2. they pass into a tube
  3. all of the glucose, some ions and water is reabsorbed back into the blood= selectively reabsorbed
  4. urea, excess ions and water are released as urine as they aren't needed
• describe how the body deals with excess amino acids?

  1. proteins are long chains of AMAC
  2. when protein is digested, AMAC pass into the blood
  3. too much protein = liver breaks down the excess AMAC and produces the chemical ammonia = deamination
  4. ammonia is very toxic so liver converts it to urea
  5. urea is excreted by the kidneys