B3.3 Homeostasis

Question 1

Where is urea produced?

Answer 1

in the LIVER

Question 2

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

Answer 2

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

Question 3

Then do water and ions enter the body?

Answer 3

When we eat and drink

Question 4

Describe how a healthy kidney produces urine

Answer 4

• filters the blood
• reabsorbs all the sugar
• reabsorbs dissolved ions needed by the body
• reabsorbs as much water as the body needs
• releases urea, excess ions and water as urine

Question 5

What are the 2 ways that people who suffer from kidney failure can be treated?

Answer 5

dialysis

kidney transplant

Question 6

Describe how kidney dialysis works

Answer 6

in a dialysis machine, a person’s blood flows between partially permeable membranes.

The dialysis fluid contains the same concentration of the useful substances as the blood.

This ensures that glucose and useful mineral ions are not lost. Urea passes out from the blood into the dialysis fluid

Question 7

What are some disadvantages and advantages of kidney dialysis?

Answer 7

it restores the concentrations of dissolved substances in the blood to normal levels

readily available, no waiting list

it has to be carried out at regular intervals

may cause blood clots or infection

Question 8

Describe a kidney transplant

Answer 8

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

Question 9

What are some disadvantages of kidney transplants

Answer 9

• lack of donor organs

- kidney may be rejected by the immune system unless precautions are taken

Question 10

Describe why a kidney may be rejected

Answer 10

immune system produces antibodies

which attack the antigens on the transplanted kidney

Question 11

How can you prevent rejection of a transplanted kidney?

Answer 11

• A donor kidney with a ‘tissue-type’ similar to that of the recipient is used
• The recipient is treated with drugs that suppress the immune system

Question 12

What monitors and controls body temperature?

Answer 12

the thermoregulatory centre in the brain

Question 13

Describe the thermoregulatory centre in the brain

Answer 13

it monitors and controls body temperature

It has receptors sensitive to the temperature of blood flowing through the brain

temperature receptors in the skin send impulses to the thermoregulatory centre, giving information about skin temperature

Question 14

What happens if the core body temperature is too high?

Answer 14

blood vessels supplying the skin capillaries dilate so that more blood flows through the capillaries and more heat is lost (easier for heat to be transferred from the blood to the environment) - This is why the skin looks red when we are hot

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

Question 15

Describe what happens if the core body temperature is too low?

Answer 15

• Blood vessels supplying the skin capillaries constrict to reduce the flow of blood through the capillaries
• Muscles may ‘shiver’- their contraction needs respiration, which releases some energy to warm the body

Question 16

What controls the blood sugar concentration of the body?

Answer 16

the PANCREAS

Question 17

Describe how the pancreas controls blood sugar levels

Answer 17

• produces a hormone called INSULIN which allows the glucose to move from the blood into the cells
• produces GLUCAGON when blood glucose levels fall. This causes GLYCOGEN to be converted into GLUCOSE and be released into the blood

Question 18

What temperature do enzymes in the body work most effectively?

Answer 18

37 degrees

Question 19

Describe type 1 diabetes and how it can be controlled

Answer 19

it is 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

it can be controlled by careful attention to diet, exercise and by injecting insulin

can have a pancreas transplant- problems of rejection ect

Question 20

What is homeostasis?

Answer 20

the maintenance of a constant internal environment

Question 21

What happens if someone with kidney failure is not treated?

Answer 21

may die because toxic substances accumulate in their blood

Question 22

What 4 things does the body need to monitor?

Answer 22

body temperature

water content

ion content

blood sugar

Question 23

What are 2 waste products that have to be removed from the body?

Answer 23

carbon dioxide- produced by respiration and removed via the lungs when we breathe out

urea- produced in the liver by the breakdown of amino acids and removed by the kidneys in the urine, which is temporary stored in the bladder

Question 24

How is insulin for diabetics made?

Answer 24

genetic engineering

Question 25

What helps to remove glucose from the blood?

Answer 25

vigorous exercise

Question 26

What are some symptoms of kidney disease?

Answer 26

accumulation of toxins in blood protein and blood in urine

Question 27

Give 3 functions of the kidney

Answer 27

- maintain correct water concentration of the blood - maintain correct ion concentration of the blood - Production of urine to remove urea

Question 28

What hormone is released when blood sugar levels are too high and what effect does this have on the body?

Answer 28

insulin allows glucose to move into cells for respiration and allows glucose to move into the liver where it is converted into glycogen

Question 29

What hormone is released when blood sugar levels are too low and what effect does this have on the body?

Answer 29

Glucagon causes glycogen in the liver to be converted to glucose and released into the blood

Question 30

What happens if there is too much carbon dioxide in the blood?

Answer 30

makes the blood become acidic- denatures enzymes

Question 31

What happens if there is too much urea in the blood?

Answer 31

poisons cells

Question 32

Where is urea made and what is it is product of?

Answer 32

a product of the breakdown of amino acids in the liver

Question 33

What are some advantages of a kidney transplant?

Answer 33

no need to control diet high success rate

Question 34

What should someone do if they are losing a lot of sodium (salt) through sweating?

Answer 34

Eat more food which contains sodium - (increase intake of sodium) stay indoors + be less active so they sweat less

Question 35

Suggest why someone may overheat in humid conditions

Answer 35

sweat is released but it can not evaporate because of the high humidity so less heat is lost (less cooling) as it is the evaporation of sweat that cools the body

Question 36

Explain why the levels of glucose in the blood increase if someone has not eaten for a long period of time

Answer 36

because glucagon (made in the pancreas) causes glycogen in the liver to be converted into glucose glucose is then released into the blood stream

Question 37

Describe the processes that prevent glucose being excreted in the urine

Answer 37

glucose is filtered out of the blood by the kidneys the filtered glucose is then taken back into the blood (reabsorbed) by active transport

Question 38

Explain why someone with kidney disease has protein in the urine but someone who does not have kidney disease has no protein in the urine

Answer 38

in a healthy person, protein is not present because protein molecules are large and so they can not pass through the filter in the kidneys in a person with kidney disease, the protein allows protein through

Question 39

What are some advantages of a kidney transplant over dialysis and some disadvantages?

Answer 39

advantages of transplant over dialysis: keeps blood concentration constant, prevent high blood pressure, don't need to restrict diet,dialysis may cause blood clots, transplant is cheaper disadvantages of transplant over dialysis: problems finding tissue match, rejection, dangers during operation, require immuno-suppressant drugs

Question 40

Describe how the brain monitors body temperature exam answer = learn

Answer 40

thermoregulatory centre has receptors which monitor blood temperature as it flows through the brain temperature receptors in the skin send impulses to the brain

Question 41

Why is drinking sports drinks bad for people with diabetes?

Answer 41

sports drinks contain a lot of glucose a person with diabetes does not produce enough insulin so blood glucose levels will rise too high

Question 42

During exercise, why does the core body temperature increase?

Answer 42

due to increased respiration + muscle contraction which releases energy

Question 43

During exercise, why does the skin temperature decrease?

Answer 43

sweating sweat evaporates and cools the skin

Question 44

Describe how the body responds when the blood glucose concentration begins to decrease

Answer 44

pancreas detects low blood glucose produces glucagon glycogen is converted into glucose