B3.3 Homeostasis

Question 1

What waste products need to be removed form the body?

Answer 1

Carbon dioxide and urea

Question 2

What is carbon dioxide produced by?

Answer 2

Respiration

Question 3

How is carbon dioxide removed?

Answer 3

Via the lungs when we breathe out

Question 4

What is urea produced by?

Answer 4

The liver in the breakdown of amino acids

Question 5

How is urea removed?

Answer 5

By the kidneys in the urine, which is temporarily stored in the bladder

Question 6

What may happen if the water or ion content of the body is wrong?

Answer 6

Too much water may move into or out of the cells and damage them

Question 7

How do water and ions enter the body?

Answer 7

When we eat and drink

Question 8

How does a healthy kidney produce urine?

Answer 8

It filters the blood, then it reabsorbs all the useful subsatances such as: sugar, dissolved ions, and as much water that the body needs. Then it releases urea, excess ions and water as urine

Question 9

How may people suffering kidney failure be treated?

Answer 9

Either by using a kidney dialysis machine or by having a healthy kidney transplanted

Question 10

What does treatment by dialysis do?

Answer 10

It restores the concentrations of dissolved substances in the blood to normal levels and has to be carried out at regular intervals

Question 11

In a dialysis machine, what does a person’s blood flow through?

Answer 11

A partially permeable membrane

Question 12

What concentration does the dialysis fluid contain?

Answer 12

The same concentration of useful substances as the blood. This ensures that glucose and useful mineral ions are not lost

Question 13

In dialysis, what does urea pass in to?

Answer 13

The dialysis fluid from the blood

Question 14

What happens in a kidney transplant?

Answer 14

A diseased kidney is replaced with a healthy one from a donor

Question 15

What may happen to the transplanted kidney?

Answer 15

It may be rejected by the immune system unless immunosuppressant drugs are taken to prevent this from happening

Question 16

What are antigens?

Answer 16

Proteins on the surface of cells

Question 17

What may the recipient of the transplant’s antibodies do to the antigens on the donor organ?

Answer 17

Attack them as they do not recognise them as part of the recipient’s body

Question 18

How do you prevent the rejection of the transplanted kidney?

Answer 18

A donor kidney with a similar tissue-type to the recipient is used and the recipient is treated with drugs that suppress the immune system (immunosuppressant drugs)

Question 19

What does sweating help to do?

Answer 19

Cool the body

Question 20

More water is lost when it is…

Answer 20

Hot, and more water has to be taken in as drink or food to balance this loss

Question 21

What is body temperature monitored and controlled by?

Answer 21

The thermoregulatory centre in the brain

Question 22

What does the thermoregulatory centre of the brain have?

Answer 22

Receptors sensitive to the temperature of the blood flowing through the brain

Question 23

What do temperature sensors in the skin also do?

Answer 23

Send impulses to the thermoregulatory centre, giving information about skin temperature

Question 24

What happens in blood vessels if the core temperature is too high?

Answer 24

Blood vessels supplying the skin capillaries dilate so that more blood flows through the capillaries and more heat is lost

Question 25

What happens in sweat glands if the core temperature is too high?

Answer 25

Sweat glands release more sweat which cools the body as it evaporates

Question 26

What happens in the blood vessels if the core temperature is too low?

Answer 26

Blood vessels supplying the skin capillaries constrict to reduce the flow of blood through the capillaries

Question 27

What happens in the muscles if the core temperature is too low?

Answer 27

The muscles may shiver, their contraction needs respiration, which releases some energy to warm the body

Question 28

What is the blood glucose concentration monitored and controlled by?

Answer 28

The pancreas

Question 29

What hormone does the pancreas produce?

Answer 29

Insulin

Question 30

What does insulin allow the glucose to do?

Answer 30

Move from the blood into the cells

Question 31

When is glucagon produced?

Answer 31

It is produced in the pancreas when blood glucose levels fall

Question 32

What does glucagon cause?

Answer 32

Glycogen to be converted into glucose and to be released into the blood

Question 33

What is type 1 diabetes?

Answer 33

A disease in which a person’s blood glucose concentration may rise to a high level because the pancreas does not produce enough of the hormone insulin

Question 34

How can type 1 diabetes be controlled?

Answer 34

By careful attention to diet, exercise and by injecting insulin