Excretion

Question 1

How do doctors treat patients with kidney disease?

Answer 1

They use dialysis or kidney transplantation.

Question 2

What are the 4 main excretory products made by cells?

Answer 2

Carbon dioxide, mineral salts, water, and urea.

Question 3

What other toxic materials have to be removed from the blood?

Answer 3

Alcohol.

Question 4

What are the three main excretory organs?

Answer 4

The lungs, the kidneys and the skin.

Question 5

What do the lungs excrete?

Answer 5

Carbon Dioxide.

Question 6

What does the skin excrete?

Answer 6

Sweat.

Question 7

What do the kidneys excrete?

Answer 7

Urine, a solution containing urea, mineral ions and other waste substances.

Question 8

Where is urea made?

Answer 8

In the liver.

Question 9

How many kidneys are there?

Answer 9

2

Question 10

How do the kidneys work?

Answer 10

They filter the blood, reabsorb all the sugar and any dissolved ions needed by the body, and reabsorb as much water as the body needs.

Question 11

If the body does not have enough water, what happens to the urine?

Answer 11

It becomes more concentrated, conserving more water.

Question 12

How does haemodialysis work?

Answer 12

Blood passes through the machine, passed the dialysis fluid that is separated via a partially permeable membrane. Urea and other waste substance diffuse from the blood to the fluid. Useful substances remain in the blood by controlling the concentration in the dialysis fluid. Excess water leaves the blood by osmosis.

Question 13

What are disadvantages of haemodialysis?

Answer 13

The patient must be connected for 4 to 5 hours, often in a hospital 3 times a week.
The patient has to have a restricted diet.
Costs £35000 per year.
Possible infection from equipment.
Availability of machines and expert staff.

Question 14

How does peritoneal dialysis work?

Answer 14

Dialysis fluid is inserted into the abdominal fluid, waste materials diffuse out of the blood, through the peritoneal membrane into the cavity. The fluid is then drained away plus the waste.

Question 15

What are the advantages of a kidney transplant?

Answer 15

Recipient freed from dependency on machines.
Long term costs less that dialysis.
Diet less restricted.

Question 16

What are the disadvantages of a kidney transplant?

Answer 16

Risk of rejection, so immune system must be suppressed.
Costs about £17000 per patient.
Check-ups needed
Availability of donors.

Question 17

What are the advantages of haemodialysis?

Answer 17

Patient kept alive while waiting for transplant.

Suitable for patients with abdominal scars and wounds who cannot have peritoneal dialysis.

Question 18

What are the advantages of peritoneal dialysis?

Answer 18

Patient kept alive while waiting for transplant.
Can be done at home at times to suit, by the patient.
Only bags of fluid needed when travelling.
Diet may be less restricted than when on haemodialysis.

Question 19

What are the disadvantages of peritoneal dialysis?

Answer 19

Patient must maintain strict hygienic conditions.
Costs £17500 a year.
Not suitable for people with abdominal wounds or scars.
Regular monitoring.