function

• • the kidneys make urine and filter blood to remove waste products and excess water
• process:

  1. filter blood
  2. selective reabsorption
• urea:

  • proteins broken down into amino acids
  • amino acids cannot be stored in body
  • excess amino acids converted into fats and carbohydrates in liver
  • this is known as deamination
• ammonia:

  • ammonia produced as waste product from deamination
  • ammonia is toxic so converted into urea in liver
  • urea transported to kidney, filtered out of blood and excreted in urine
• ions and water:

  • ions and water lost in sweat
  • water lost from lungs when breathing out
  • water controlled by kidneys through urine
  • ions controlled through selective reabsorption
• • if water concentration is too high outside cell, water enters cell by osmosis
  • cell becomes hypotonic
  • cells swell and burst
• • if water concentration is too low outside cell, water leaves cell by osmosis
  • cell become hypertonic
  • cells shrivel