Kidneys

• What 3 ways does water leave the body?

  Lungs when exhale, sweat water lost through skin, urine through kidneys
• What do the kidneys do if the urine is too dilute?

  remove excess water produce greater volume of urine
• What else is removed in urine besides excess water

  ?

  urea excess ions
• How do the kidneys work?

  blood enter kidney through artery. blood contain urea. kidney remove urea, ions and excess water. excess stuff leave kidney as urine and stored in bladder. blood leave kidney through vein
• How do the kidneys adjust the level of molecules in the blood?

  blood passes through capillaries, small molecules filtered out of blood. E.g. urea, ions, water glucose. Pass through tubes all of glucose some ions some water reabsorbed back into blood ( selective reabsorption). Urea, excess ions and water released as urine.
• What are proteins made from?

  long chains of amino acids
• What does the body do when we eat too many proteins?

  liver breaks down amino acids, produces ammonia ( deamination )
• Why does the liver convert ammonia to urea?

  ammonia is toxic chemical urea easily excreted by kidneys
• What happens if the blood in the body is too concentrated?

  pituitary gland releases ADH into bloodstream. ADH travel to kidney cause kidney tubules become more permeable to water. More water absorbed from tubules back into blood. Less urine produced. Water level back to normal pituitary gland stop releasing ADH
• What happens if the blood in the body becomes too dilute?

  water in blood rise. pituitary gland stop releasing ADH. Kindeys reabsorb less water into blood. More urine produced
• How does kidneys dialysis work?

  patient blood pass over semi-permeable membrane. Urea, ions and water able to get through. Larger molecules not able to pass through e.g. protein. Dialysis fluid on other side of semi-permeable membrane, has normal amount of water and ions but no urea. Concentration gradient for urea to diffuse from blood into dialysis fluid. Dialysis fluid refreshed to make large concentration gradient
• What are the disadvantages of kidney dialysis?

  Dialysis machines expensive. Patients need to follow controlled diet. Only successful for certain amount of time
• What are the advantages of kidney dialysis?

  no major surgery. can keep patient alive while donor is found
• What happens in a kidney transplant?

  diseased kidney replaced with healthy one from donor
• What are the advantages of a kidney transplant?

  no diet restrictions. improved quality of life. dont need dialysis machine
• What are the disadvantages of a kidney transplant?

  patient needs to take drugs to suppress immune system in case of rejection. risks from surgery e.g. bleeding, blood clotting. Donor has to be found