The Kidneys

• The Kidneys are really important in this whole homeostasis thing
• Kidneys Basically Act as

  Filters to "Clean the Blood" and remove waste products (and other unwanted substances) out of your blood
• The kidneys make urine

  1. Substances are filtered out of the blood as it passes through the kidneys

  2. Useful substances like glucose some ions and the right amount of water are then absorbed back into the blood (selective reabsorption)
• Substances Removed from the Body in Urine

  • Urea
  • Ions
  • Water
• Urea


  Excess amino acids are converted into urea in the liver, which is then transported to the kidneys and filtered out of the blood and excreted from the body in urine
• Ions


  Ions such as sodium are taken into the body in food, and then absorbed into the blood. The right balance of ions must be maintained by the kidneys, with the right amount reabsorbed into the blood and the rest removed in urine
• Water


  The body has to constantly balance the water coming in against the water going out (through sweat, breathing, and urine). The kidneys regulate the amount of water in the body
• Having the wrong amount of water can damage cells or mean they don't work as well as normal
• Some ions are lost in sweat, but this amount isn't regulated, so the right balance of ions in the body must be maintained by the kidneys