Topic 5b- Controlling water content in blood

Question 1

What is the function of the kidneys?

Answer 1

To take urea and other waste products out of your blood.

Question 2

What is it called when the kidneys extract substances out the blood when it passes through them?

Answer 2

Filtration

Question 3

What is it called when useful substances are taken back into the blood from the kidneys?

Answer 3

Selective reabsorbtion

Question 4

What substances are removed from the blood by the kidneys?

Answer 4

Urea, excess ions and water.

Question 5

How does your body regulate water content in the blood?

Answer 5

Sweating and urinating

Question 6

What are excess amino acids in the body turned into? Where does this occur? What toxic substance is produced?

Answer 6

Fats and carbohydrates.
Occurs in the liver. The toxic substance (ammonia) is produced due to this process which the liver then turns into urea.

Question 7

What is the name of the process in the liver that converts amino acids into storable nutrients while producing a by-product of ammonia?

Answer 7

Deamination

Question 8

What is ammonia converted into in the liver?

Answer 8

Urea

Question 9

What is ADH?

Answer 9

Anti-diuretic hormone

Question 10

Where does filtration and selective reabsorbtion take place in the kidneys?

Answer 10

The kidney tubules

Question 11

What does ADH do?

Answer 11

Control how much water is lost from the kidney tubules back into the blood.

Question 12

What does ADH do to the cells of the kidney tubules?

Answer 12

Causes them to be more permeable and so changing the volume of water that can be reabsorbed into the blood.

Question 13

What happens if the water content in the blood is too high?

Answer 13

1. A receptor in the brain detects that the water content is too high.
2. The coordination centre in the brain recieves this information and coordinates a response.
3. The pituitary gland releases less ADH.
4. The kidney tubules become less permeable and less water is reabsorbed into the blood from the kidney tubules.
5. Water content in the blood decreases.

Question 14

What happens if the water content in the blood is too low?

Answer 14

1. A receptor in the brain detects that the water content is too low.
2. The coordination centre in the brain recieves this information and coordinates a response.
3. The pituitary gland releases more ADH.
4. The kidney tubules become more permeable and more water is reabsorbed into the blood from the kidney tubules.
5. Water content in the blood increases.

Question 15

What are three substances in a healthy person’s urine?

Answer 15

• urea
• water
• (excess) ions

Question 16

What are effects of kidney failure?

Answer 16

• waste substances build up in the blood
• inability to control ion and water level in blood

Question 17

How does a dialysis machine work?

Answer 17

1. Patient’s blood flows alongside a partially permeable membrane, surrounded by dialysis fluid.
2. Partially permeable membrane allows things like ions and waste substances through but not big molecules like proteins.
3. The dialysis fluid has the same concentration of dissolved ions and glucose as helthy blood.
4. This means useful dissolved ions and glucose do not diffuse across the membrane while urea and excess ions do.

Question 17

What are treatment options for kidney failure?

Answer 17

1. Having dialysis treatment- where machines do the job of the kidneys
2. Having a kidney transplant- where the diseased kidney is replaced by a healthy one.

Question 18

What are some problems with dialysis?

Answer 18

• Not a pleasant experience- patients have to go for 3-4 hours, 3 times a week
• Can lead to infections and cause blood clots
• Patients have to be careful with what they eat between sessions to avoid too much of a particular ion building up
• Patients have to limit their fluid intake
• Expensive

Question 19

Where can kidneys be supplied from for kidney transplants?

Answer 19

• Recently dead
• 1 kidney from someone alive (as we can live with 1 kidney)

Question 20

What is the problem with kidney transplants?

Answer 20

Rejection- antigens on the donors kidneys are recognised as foreign and antibodies are produced by the white blood cells causing the immune system to attack the donor cells as a result.

Question 20

What precautions can be taken to try and prevent rejection of a donor organ?

Answer 20

• Donor with a tissue type that closely matches the patient’s
• Patient treated with immunosuppressants

Question 21

Problems with kidney transplants

Answer 21

• Long waiting lists for kidneys
• Even if kidney has matching tissue type, still possibility of rejection
• Immunosuppressants make patient vulnerable to other illnesses and infections
• Kidney transplant is a major operation so it can be risky