5.2.4 Treating kidney failure

Question 1

What are the two ways that you can treat kidney failure?

Answer 1

• Renal dialysis
• Kidney transplant.

Question 2

What are the advantages of a kidney transplant?

Answer 2

• The patient has much more freedom as they are not tied to dialysis several times a week in one place.
• The use of dialysis machines is very expensive and so the cost is removed.
• A kidney transplant is a long-term solution whereas dialysis will only work for a limited time.

Question 3

What are the disadvantages of a kidney transplant?

Answer 3

• Donors don’t have the same antigens on cell surfaces so there will be some immune response to the new kidney.
• This has to be suppressed by taking immunosuppressant drugs for the rest of their lives.
• There are not enough doctors to cope with the demand.

Question 4

What is the disadvantage of taking immunosuppressant drugs?

Answer 4

• These can have long-term effects and leave the patient vulnerable to infections.

Question 5

What is haemodialysis?

Answer 5

• The patient requires regular treatment in a hospital using a machine known as a haemodialyser, which acts as an artificial kidney.

Question 6

Describe a haemodialyser.

Answer 6

• Partially permeable dialysis membranes separate the patients blood from the dialysis fluid.

Question 7

What does dialysate contain?

Answer 7

• Substances needed in the blood in the right concentrations.

Question 8

Since dialysate contains a glucose concentration equal to a normal blood sugar level, what does this prevent?

Answer 8

• The net movement of glucose across the membrane as no concentration gradient exists.

Question 9

What component is not found in dialysate?

Answer 9

• Urea.

Question 10

Describe how dialysate allows the movement of salts across the membrane?

Answer 10

• Due to dialysis containing a salt concentration similar to the ideal blood concentration, however this only occurs if there is an imbalance.

Question 11

Why is the fluid in the machine constantly refreshed?

Answer 11

• So that concentration gradients are maintained between the dialysis fluids and the blood.

Question 12

The haemodialyser is designed so that…

Answer 12

• The patient’s blood and the dialysate flow in opposite directions, creating a concentration gradient along the length of the dialyser component of the machine.

Question 13

Why is the drug heparin added to the haemodialyser?

Answer 13

• Heparin is added to the blood as an anticoagulant (blood thinner) that prevents the formation of blood clots.

Question 14

What is peritoneal dialysis?

Answer 14

• Dialysate is introduced to the abdominal cavity through a catheter.

Question 15

What products diffuse into the dialysate during peritoneal dialysis?

Answer 15

• Urea, other metabolic waste products and excess substances.

Question 16

What is the disadvantage of both types of dialysis?

Answer 16

• Both forms a dialysis impose heavy restrictions on the lives of patients that rely on them.
• Patients have to carefully control their diet to minimise their urea production and their salt intake.