The kidneys

• What do the kidneys do

  Make urine by taking waste products and other unwanted substances out of the blood
• what is filtration

  substances are filtered out of the blood as it passes through the kidneys
• what is selective reabsorption

  useful substances like glucose, some ions and the right amount of water are absorbed back into the blood
• what substances are removed from the body in urine

  urea

  ions

  water
• What happens to excess amino acids

  They can’t be stored by the body

  they’re converted into fats and carbohydrates

  this happens in the liver and involves a process called deamination

  ammonia is produced as a waste product
• what happens to ammonia in the body

  ammonia is toxic so its converted into urea in the liver
• what happens to urea in the body

  it’s transported to the kidneys

  its filtered out of the blood and excreted from the body in urine
• what happens if the ion content of the body is wrong

  it can upset the balance between ions and water

  so too much or too little water is drawn into cells by osmosis

  having the Wong amount of water can damage cells
• how is the balance of ions maintained

  some ions are lost in sweat but this isn’t regulated

  the kidneys maintain the right balance of ions

  the right amount of ions are reabsorbed after filtration and the rest are removed in urine
• how is water controlled in the body

  Water is lost from the skin in sweat and from the lungs when breathing

  the amount of water is balanced by the amount we consume and he amount removed b the kidneys in urine
• what hormone controls the concentration of urine

  ADH
• what releases ADH

  pituitary gland
• when is ADH released

  the brain monitors the concentration of water in the blood

  it instructs the pituitary gland to release ADH
• what happens when the water content is too high

  a receptor in the brain detects that the water content is too high

  CNS receives this information and coordinates a response

  pituitary gland releases less ADH so less water is reabsorbed from the kidney tubules
• what happens when the water content is too low

  a receptor in the brain detects that the water content is too low

  CNS receives this information and coordinates a response

  pituitary gland releases more ADH so more water is reabsorbed from the kidney tubules