Kidney failure 5.2.9

Question 1

Give 4 reasons as to why kidney failure can occur

Answer 1

• High blood pressure
• Diabetes
• Blood loss in an accident
• Overuse of certain drugs

Question 2

What happens if kidneys fail?

Answer 2

• Urea, water, salts, and various toxins are retained and not excreted
• Less blood is filtered by the glomerulus, causing the glomerular filtrate rate to decrease
• This leads to a build up of toxins in the blood
• Also, the electrolyte balance of the blood is disrupted

Question 3

How long can kidney failure last

Answer 3

• Sometimes happens suddenly and only lasts for a short time
• In other cases it can become a long term condition

Question 4

Why is electrolyte balance in the blood important?

Answer 4

• Can have harmful consequences
• Excess K ions can lead to abdominal cramps, tiredness, muscle weakness, and even paralysis
• If K ions continue to increase, frequency of impulses from SAN decreases leading to arrhythmia
• Kidneys either conserve or secrete sodium which plays important role in neuromuscular function and fluid balance
• Build up of sodium can cause muscle spasms and high blood pressure

Question 5

How many kidneys can humans survive with?

Answer 5

One

Question 6

What happens if both kidneys are damaged?

Answer 6

There will quickly be a build up of toxic wastes in the body which will be fatal if not removed

Question 7

What are the two forms of treatment for kidney failure?

Answer 7

• Renal dialysis
• Kidney transplant

Question 8

Explain renal dialysis

Answer 8

Toxins, metabolic waste products, and excess substances are removed from the blood by diffusion via a dialysis membrane

Question 9

Explain kidney transplant

Answer 9

The non functioning kidney(s) are replaced with a functioning one

Question 10

Describe the term dialysis

Answer 10

Describes the separation of small and large molecules using a partially permeable membrane

Question 11

Explain haemodialysis

Answer 11

In this dialysis machine, partially permeable dialysis membrane separates the blood from the dialysis fluid - which is passed through tubes surrounded by this dialysate. The blood and the fluid also flows in opposite directions
The dialysate contains substances needed in the blood (e.g. glucose, amino acids) in the right concentrations.
This allows the correct solute concentration to be constantly maintained in the patients blood as when there is an imbalance the movement of salts or glucose occurs into the blood
This dialysate contains no urea, so this causes urea to diffuse down its concentration gradient from the blood into the machine where it is disposed of
The drug heparin is added to the blood which acts as a anticoagulant and prevents the formation of blood clots

Question 12

What is the purpose of the countercurrent flow in a haemodialysis machine?

Answer 12

To ensure that a concentration gradient is constantly maintained between the blood and the dialysate

Question 13

What are 4 disadvantages of renal dialysis

Answer 13

• Imposes heavy restrictions on patients lives ; have to live with a machine
• Expensive
• Diet care
• Make regular trips to the hospital

Question 14

What is the function of the drug heparin?

Answer 14

It is an anticoagulant that prevents the formation of blood clots

Question 15

Why is urea not in the dialysate

Answer 15

To force urea to diffuse down its concentration gradient from the blood into the dialysate, where it is eventually disposed of

Question 16

When does the movement of solutes only occur in dialysis

Answer 16

When there is an imbalance (if blood is too high/low in salts for example)

Question 17

What must be found fora kidney transplant to occur

Answer 17

A donor with a compatible blood group

Question 18

What medication must a kidney transplant patient take and why?

Answer 18

Immunosuppressants to stop their immune system from rejecting the donated kidney as this kidney will often be of a different tissue type

Question 19

What are three disadvantages to kidney transplants

Answer 19

• Donors won’t have the same antigens on cell surface membranes so there will be some immune response to the new kidney (risk of rejection is reduced by tissue typing the donor and patient first)
• Has to take immunosuppressants for the rest of their lives
• There are not enough donors to cope with the demand

Question 20

What are four benefits of kidney transplants

Answer 20

• Patient has much more freedom as they are not tied to having dialysis several times a week in one place
• Their diets can be much less restrictive than they are when on dialysis
• Use of dialysis machines is very expensive
• Kidney transplant is a long term solution