Kidney dialysis

Homeostasis

What can disease or damage to kidneys affect?

Ability to remove toxic waste substances from the body.

How many kidneys does a human need to function?

Only one, but in case of total kidney failure, treatment is needed urgently.

How can kidney failure be treated?

An organ transplant or kidney dialysis

Who uses a dialysis machine?

Patients who are waiting for a suitable donor to become available for an organ transplant.

What does kidney dialysis use?

Specialised equipment, usually in a hospital setting.

What first happens during dialysis?

Unfiltered blood is taken from the body via a blood vessel in the arm.

What is the blood from the arm mixed with?

Anti-coagulants to prevent the natural blood clotting.

What happens to this blood after mixing with anti-coagulants?

It is pumped into the dialysis machine.

What is inside the dialysis machine?

A partially permeable membrane which seperates the patients unfiltered blood from the dialysis fluid.

What direction does blood flow in a dialysis machine?

In the opposite direction to the dialysis fluid to ensure concentration gradient is maintained and exchange of substances can occur.

What does dialysis fluid contain?

Glucose, ions and no urea.

What happens to urea in the blood?

It moves across the partially permeable membrane, down the concentration gradient and into dialysis fluid by diffusion.

What is important about the concentrations of glucose and ions in the dialysis fluid?

They are similar to that within blood plasma, so they are only exchanged across the membrane if there is an imbalance and safe levels are maintained.

Advantages of kidney dialysis

• Allows a patient with kidney failure to maintain their health.

• Reduces levels of urea in the blood

• Maintains glucose levels

• Restores natural water and ion levels.

Disadvantages of kidney dialysis

• Expensive

• Time consuming and restrictive on lifestyle - 4-6 hours, 2 to 3 times a week.

• Only effective whilst the dialysis is being run so patients must monitor their levels carefully between treatments.

• Diet restrictions - avoid high salt foods and excessive protein.

• Only effective for a limited time - many patients die waiting for a transplant.