The kidney

• how is water lost from the body?

  urine

  sweat

  water vapour from lungs
• what is the control of water levels and mineral salts in the blood?

  osmoregulation
• if the body cells lose or gain too much water by osmosis they dont function efficiently
• what is excretion?

  removal of urine
• The digestion of proteins leads to and excess of amino acids which need to be excreted
• where are the amino acids deaminated ( broken down) to form ammonia?

  liver
• what is ammonia converted into?

  urea
• Urea and water are released from the liver cells in to the blood stream and transported to the kidneys where the blood is filtered and urea is passed through the body in urine
• what are the roles of the kidney?

  ~ regulate the water content of the blood

  ~ excrete toxic waste products
• describe how the water content of the blood is controlled?

  if water too low then ADH will be released from the pituitary gland toward the blood. Allows the kidney to absorb more water and a smaller volume of urine is made. allows the kidney tubules to become more permeable
• what is the function of insulin?

  lowers blood glucose levels
• what is the function of glucagon ?

  raises blood glucose levels
• A high concentration f glucose can be harmful to body cells as a result of osmosis why?

  water diffuses from a dilute to concentrated solution through a permeable membrane which causes cells to shrink
• The kidneys produce urine by filtration of the blood and selective reabsorption of useful substances such as glucose, some ions and water.
• The water level in the body is controlled by the hormone ADH which acts on the kidney tubules. ADH is released by the pituitary gland when the blood is too concentrated and it causes more water to be reabsorbed back into the blood from the kidney tubules. This is controlled by negative feedback.
• patients who suffer from kidney failure usually get treated with dialysis or will receive a kidney transplant
• why would a person need to use a dialysis machine?

  kidney doesnt work to control the level of dissolved substances in the body
• why is it important that the dialysis machine should have same concentration of dissolved substances as healthy blood?


  so useful substances wont be lost from persons blood
• what are the advantages of a kidney transplant?

  can lead a normal life after transplant so no dialysis
• what are the disadvantages of kidney transplant?

  long waiting list and not always available