5.12 - Kidneys (Dialysis and Transplants)

• Main Consequences of Kidney Failure:

  • build up of waste substances in the blood stream
  • unable to regulate water and ion levels
  • become sick
  • possibility of death
• Only ways to treat kidney failure are dialysis or a kidney transplant
• Dialysis:

  • filter a patients blood for them
  • patients blood is pumped through the dialysis machine, where dialysis fluid is stored.
  • dialysis fluid contains the same concentration of water and other molecules as healthy blood does.
  • there is a partially permeable membrane between the blood and dialysis fluid, so the molecules needed/unwanted are able to diffuse in and out of the patients bloodstream using the concentration gradient made.
• Problems with Dialysis:

  • Time consuming - have to go into hospital 3-4 days a week for 3-4 hours each time.
  • Unpleasant
  • can cause blood clots and infection
  • Expensive
  • Life long
• Kidney Transplant:

  • Surgical procedure to replace a faulty kidney with a working one.
• Risks with Kidney Transplant:

  • Organ will be rejected - transplanted organ is attacked by patients immune system
  • Doesn’t always work
• In a dialysis machine, why is it important that the membrane between the blood and dialysis fluid is partially permeable?

  To only allow some substances to diffuse across
• In a dialysis machine, why is it important to continually pump fresh dialysis fluid through the machine?

  To maintain a concentration gradient for diffusion across the membrane
• Will fresh dialysis fluid contain urea?

  No, the dialysis fluid contains the ideal concentration of each substance, so won’t contain any urea.
• If a patient has a kidney transplant, what type of drugs are they required to take for the rest of their lives?

  Immunosuppressants