Homeostasis

Question 1

What does homeostasis mean?

Answer 1

Keeping your internal environment constant.

Question 2

What 5 things does homeostasis include monitoring and controlling?

Answer 2

1. Waste materials.
2. Body temperature.
3. Water content
4. Ion content.
5. Blood glucose levels.

Question 3

What 2 waste materials have to be removed from the body?

Answer 3

1. Carbon dioxide.

2. Urea.

Question 4

How is carbon dioxide produced?

Answer 4

By respiration.

Question 5

How is carbon dioxide removed from the body?

Answer 5

Via the lungs when we breathe out.

Question 6

How is urea produced?

Answer 6

In the liver by the breakdown of amino acids.

Question 7

How is urea removed from the body?

Answer 7

By the kidneys. It is temporarily stored in the bladder and then excreted as urine.

Question 8

What temperature should the body be kept constant at?

Answer 8

37^oC

Question 9

What 3 things does the thermoregulatory centre in the brain do?

Answer 9

1. Monitors and controls body temperature.
2. Has receptors that monitor the temperature of the blood flowing through the brain.
3. Receives information (impulses) from temperature receptors in the skin.

Question 10

Why do people sweat?

Answer 10

To cool the body. When it is hot, more water is lost by your body, so more water has to be taken in as drink or in food to balance this lost.

Question 11

What two things does the body do when it is hot to regulate body temperature?

Answer 11

1. Sweat.

2. Skin appears flushed.

Question 12

Why does skin appear flushed when it’s hot?

Answer 12

Because there is an increased blood flow beneath its surface.

Question 13

What 2 things happen if core body temperature is too high?

Answer 13

1. Blood vessels supplying skin capillaries dilate (widen) to increase blood flow and heat loss.
2. Sweat glands release more sweat, which cools the skin as it evaporates.

Question 14

What 2 things happen if core body temperature is too low?

Answer 14

1. Blood vessels supplying skin capillaries constrict (narrow) to reduce blood flow and heat loss.
2. Muscles start to shiver, causing heat energy to be released by respiration in cells.

Question 15

What is the main function of the kidneys?

Answer 15

To maintain the concentrations of dissolved substances in the blood.

Question 16

What three things do the kidneys do?

Answer 16

1. Regulate the amount of water in the blood.
2. Regulate the amount of ions in the blood.
3. Remove all urea in the form of urine.

Question 17

How do water and ions enter the body?

Answer 17

When you eat and drink.

Question 18

Why does the level of water and ions need to be maintained?

Answer 18

Because too much water moving into or out of the cells may damage them.

Question 19

What three processes occur in the kidneys?

Answer 19

1. Ultra filtration.
2. Selective reabsorption.
3. Excretion of waste.

Question 20

What do blood vessels carry through the kidneys?

Answer 20

Blood.

Question 21

What is ultra filtration?

Answer 21

When lots of water and all the small molecules are squeezed out of the blood, under pressure, into tubules in the kidney.

Question 22

What is selective reabsorption?

Answer 22

When all the sugar, plus any ions and water needed by the body, are reabsorbed back into the blood from the tubules.

Question 23

What is excretion of waste?

Answer 23

When excess water, ions and all lof the urea pass to the bladder in the form of urine, where it’s stored before being released from the body.

Question 24

How can failed kidneys be treated?

Answer 24

1. Using a dialysis machine.

2. By having a kidney transplant.

Question 25

How does a dialysis machine work?

Answer 25

1. Blood flows through a dialysis machine. 2. The blood is separated from the dialysis fluid by partially permeable membranes. 3. The membranes allow urea, and any excess substances, to pass from the blood into the dialysis fluid. 4. Concentrations of dissolved substances in the blood are restored to their normal levels.

Question 26

What is in dialysis fluiid?

Answer 26

The same concentration of useful substances as blood. This ensures glucose and essential mineral ions aren't lost through diffusion.

Question 27

How often should dialysis be carried out?

Answer 27

At regular intervals to maintain the patient's health.

Question 28

What does a kidney transplant involve?

Answer 28

A diseased kidney being replaced with a healthy one from a donor.

Question 29

What is the main problem with kidney transplants?

Answer 29

The donor kidney might be rejected by the recipient's immune system. There are antigens on the surface of cells. The recipient's antibodies may attack the antigens on the donor organ because they don't recognise them as being part of the recipient's own body.

Question 30

What 2 things can be done to prevent rejection of the transplanted kidney in a kidney transplant?

Answer 30

1. A donor kidney with a tissue-type similar to that of the recipient is used (this is best achieved if the donor is a close relative. 2. The recipient is treated with drugs that suppress the immune system.

Question 31

What are the two main functions of the pancreas?

Answer 31

1. To monitor and control blood sugar levels. | 2. To secrete the hormone insulin.

Question 32

What does insulin do?

Answer 32

It allows glucose to move from the blood into the cells.

Question 33

What other organ does the level of insulin in the pancreas affect?

Answer 33

The liver.

Question 34

What happens if a person's pancreas doesn't produce enough enough insulin?

Answer 34

A person's glucose concentration may rise to a high level. This is called Type 1 diabetes.

Question 35

How can type 1 diabetes be controlled?

Answer 35

1. By careful management of diet and exercise. | 2. By injecting insulin into the blood.

Question 36

How is human insulin made?

Answer 36

Via genetic engineering, quickly and cheaply using bacteria.

Question 37

How does insulin work?

Answer 37

It converts glucose into glycogen, which is stored in the liver. A second hormone called glucagon is made in the pancreas when blood glucose levels fall too low. This cause glycogen to be converted into glucose and be released into the blood.

Question 38

What reaction happens between glucose and insulin?

Answer 38

Glucose glycogen

Question 39

What is glucose needed for?

Answer 39

To provide energy for the body.

Question 40

What happens if blood sugar level is too high?

Answer 40

1. Thirst. 2. Hunger. 3. Need to urinate. 4. Blurred vision. 5. Dizziness. 6. Nausea.

Question 41

What happens if blood sugar level is too low?

Answer 41

1. Hunger. 2. Weakness. 3. Inability to concentrate. 4. Dizziness. 5. Convulsions. 6. Loss of consciousness.

Question 42

Which part of the brain monitors body temperature?

Answer 42

The thermoregulatory centre.

Question 43

Where is insulin made?

Answer 43

Pancreas.

Question 44

What is urea?

Answer 44

Broken down amino acids.

Question 45

Where is urine stored?

Answer 45

In the bladder.

Question 46

If a person's kidney fails, what type of machine can be used to filter their blood?

Answer 46

Dialysis machine.