The Kidney

Question 1

How is urea taken out of the body?

Answer 1

It passes in the blood to the kidneys to be excreted.

Question 2

Where and how is water moved within the body?

Answer 2

Water moves in and out of cells through osmosis.

Question 3

What is the process of a healthy human kidney?

Answer 3

• First, the blood is filtered
• Glucose is reabsorbed
• The dissolved mineral ions needed by the body are reabsorbed
• As much water as is needed is reabsorbed
• Urea, excess mineral ions and water are released in the urine.

Question 4

What is the name for the process of only reabsorbing some water, ions etc?

Answer 4

selective reabsorption.

Question 5

Explain ADH and the water balance.

Answer 5

• If the water content is too low, more ADH is released from the pituitary gland, so more water is reabsorbed. This causes more concentrated urine.
• If the water content is too high, less ADH is released, so less water is reabsorbed. This causes more diluted urine.
• ADH works by changing the permeability of the kidney tubules so that more water is reabsorbed.

Question 6

What does a dialysis machine contain?

Answer 6

A partailly permeable membrane, surrounded by dialysis fluid.

Question 7

What does the dialysis fluid contain?

Answer 7

The same concentration of useful substances such as glucose and mineral ions as the patient’s blood.

Question 8

Why does the dialysis fluid contain useful mineral ions?

Answer 8

So that these substances do not diffuse out of the blood, and do not need to be reabsorbed.

Question 9

What diffuses out from the blood into the dialysis fluid?

Answer 9

Urea.

Question 10

What are the advantages of kidney dialysis?

Answer 10

• It restores the concentration of substances in the blood back to normal.
• It greatly reduces the levels of urea.
• It is available for all patients.
• It doesn’t require immune-suppressant drugs.

Question 11

What happens in dialysis when a patient’s blood is too low in ions?

Answer 11

They will diffuse from the dialysis fluid into the blood, restoring the ideal level in the blood.

Question 12

What happens in dialysis when a patient’s blood is too high in ions?

Answer 12

The excess ions will diffuse from the blood to the dialysis fluid.

Question 13

What are the disadvantages of kidney dialysis?

Answer 13

• It must be carried out at regular intervals.
• A patient’s diet must be carefully monitored.
• It is generally more expensive.

Question 14

What are the advantages of a kidney transplant?

Answer 14

• It only needs to be carried out once, and last for a long time.
• It is generally cheaper than dialysis.

Question 15

What are the disadvantages of a kidney transplant?

Answer 15

• The patient must take immune-suppressant drugs to prevent rejection, which can be infectious.
• It can be difficult to find a donor who has matching antigens to the patient.
• The kidney tends to only last between 8 and 9 years.