Maintaining the Bodys Water Balance

What happens if the blood becomes to concentrated(the level of water in blood falls)

1)A receptor in the brain detects that the water content is too low

2)The coordination centre in brain receives a he information and coordinate a response.

3)The pituitary gland releases the hormone ADH into bloodstream

4)ADH travels to the kidneys and causes kidney tubules to become more permeable to water(more water can pass out of kidney tubules)

5)So more water is reabsorbed from the tubules back into the blood.

6)This means less urine is produced and amount of water in blood rises back to normal levels

7)As level of water in the blood returns to normal, the pituitary gland stops releasing ADH

What happens if blood becomes too dilute(the level of water in blood rises) if someone drinks water

1)The concentration of water rises so pituitary gland stops releasing ADH

2)So kidney tubules reabsorbs less water into the blood.

3)Now more urine is produced and the concentration of water in the blood returns back to normal

When do we do kidney dialysis

When you want to be kept alive if you have kidney failure

Explain how dialysis works

1)People with kidney failure blood have a high concentration of water,ions and urea than it should

2)So in kidney dialysis the persons blood flows between the partially permeable membrane surrounded by dialysis fluid. This allows urea,ions and water through but not large molecules like protein and blood cells.

3)On the other side of membrane we have dialysis fluid which has the same concentration of dissolved ions and glucose as healthy blood but doesn’t contain urea.

4)So urea and excess ions and water diffuse across the barrier into fluid so concentration of persons blood returns to normal.

5)The dialysis fluid is constantly refreshed to ensure that there is always a large concentration gradient for urea.

What are the disadvantages of people on kidney dialysis

1)It’s inconvenient as patients have to visit several times a week

2)Also have to be on a controlled diet so they don’t produce much urea

3)It’s also expensive for the NHS to run

However, dialysis buys patients with kidney failure time until a donor organ is found.

How does a kidney transplant work and disadvantages

The disease kidney is replaced with a healthy kidney from a donor.

However, in some cases the donated kidney may be rejected by patients immune system.

Compare advantages and disadvantages of Kidney transplant and dialysis

1)No shortage of diaysis machines but there’s a shortage of kidney donors

2)Dialysis Requires frequent treatments and controlled diet while with transplant patient can live a normal life.

3)Kidney dialysis is expensive long term while transplant it’s only expensive initially

4)Kidney transplant you need to take anti-rejection drugs for rest of life while you don’t for dialysis.