B3- Keeping Internal Conditions constant

Question 1

What is meant by homeostatis?

Answer 1

This means keeping the body in the same/a steady state.

Question 2

How do the kidneys keep the body the same?

Answer 2

Kidneys keep water and ion concentration constant.

Question 3

Why is body temperature kept the same?

Answer 3

The body is kept at 37^o so that enzymes can work quickly, but do not denature.

Question 4

How is blood glucose level kept the same?

Answer 4

The pancreas releases insulin when blood glucose rises, and glucagon when blood glucose falls.

Question 5

What does a healthy kidney do?

Answer 5

A healthy kidney:

1. Filters the blood.
2. Reabsorbs all the sugar.
3. Reabsorbs as much water and ions as the body needs.
4. Releases urea, excess ions and water in the urine.

Question 6

What is urea?

Answer 6

Urea is produced in the liver when excess protein is taken in. This cannot be stored so the protein is broken down in urea.

Question 7

How is blood filtered in the kidneys?

Answer 7

Nephrons.

Question 8

How can kidney disease be treated?

Answer 8

Either by dialysis or transplant.

Question 9

What is a dialysis machine?

Answer 9

A dialysis machine carries out the same job as the kidneys. It filters the blood using a partially permeable membrane, and restores the concentration of substances in the blood back to normal.

Question 10

What is in dialysis fluid?

Answer 10

Dialysis fluid contains the same concentration of useful substances as the body needs (water, glucose and ions) so the substances do not diffuse into the dialysis fluid.

There is no urea in the fluid, therefore urea in the blood diffuses into the fluid and so is removed from the blood.

Question 11

Why must immunosuppressants be taken after a kidney transplant?

Answer 11

The antigens on the donor organ may be attacked as the recipient’s immune system sees the antigens as ‘foreign’. Therefore immunosuppressant drugs must be taken to prevent rejection.

Question 12

What are the advantages and disadvantages of using dialysis for kidney disease?

Answer 12

A- Available to all patients (no shortage).

A- No need for immunosuppressant drugs.

D- Patients must limit salt and protein intake.

D- Expensive for the NHS.

D- Regular dialysis sessions➡️Impact on the patient’s life.

Question 13

What are the advantages and disadvantages of having a kidney transplant?

Answer 13

A- Patients can lead a more normal without having to watch what they eat and drink.

A- Cheaper for NHS overall.

D- Must take immunosuppressant drugs which increase risk of infection.

D- Shortage of organ donors.

D- Kidney only lasts 8-9 years on avergae.

D- Any operation carries risk.

Question 14

Where is blood temperature monitored?

Answer 14

Thermoregulatory centre in the brain (hypothalamus). This centre has receptors which detect the temperature of the blood flowing through the brain.

Question 15

What happens when the body is too hot?

Answer 15

• Arteries supplying capillaries dilate (muscles relax). This increases blood flow into capillaries and near the surface of the skin to increase the amount of heat loss by radiation.
• Sweat glands secrete swear➡️Evaporation of sweat requires energy which comes from the skin’s surface so cools the skin down.

Question 16

What happens when the body is too cold?

Answer 16

• Arteries supplying capillaries constrict (muscles contract). This means less blood flows in capillaries and near the surface of the skin, so less heat is lost by radiation.
• We shiver (muscles contract quickly) which increases the rate of respiration and some energy released warms the blood.
• Hair stands erect➡️Traps warm layer of air (more in animals).

Question 17

What happens if body temperature is not kept constant?

Answer 17

• If body temperature is too low the respiratory ezymes work too slowly and too little energy is released.
• If body temperature is too high enzymes can denature.

Question 18

Why is insulin produced, and what does it do?

Answer 18

Insulin is produced when there is too much glucose in the blood.

Insulin converts glucose to glycogen for storage in the liver and muscles.

Question 19

Why is glucagon produced, and what does it do?

Answer 19

Glucagon is produced when there is not enough glucose in the blood.

Glucagon converts glycagen back to glucose.

Question 20

What causes type 1 diabetes and how is it treated?

Answer 20

If the pancreas is unable to produce enough insulin, the blood glucose level may become too high.

Type 1 diabetes is traditionally treated with human insulin produced by genetically engineered bacteria. The diabetic must inject themselves with insulin before meals.

Question 21

What new methods are being developed to treat type 1 diabetes?

Answer 21

• Pancreas transplants.
• Transplanting pancreas cells.
• Using embryonic stem cells to produce insulin secreting cells.
• Using adult stem cells from diabetic patients.
• Genetically engineering pancreas cells to make them work properly.

Question 22

During exercise, why would the core body temperature increase?

Answer 22

Increased respiration, so more energy released.

Question 23

During exercise, why would the skin surface temperature decrease?

Answer 23

Increased sweating (1) which evaporates and uses energy, so cools the skin (1).