Chapter 3: Keeping internal conditions constant

Question 1

What is homeostasis?

Answer 1

The art of keeping the environment inside ones body constant.

Question 2

3 examples of variables that need regulating:

Answer 2

Temperature, waste levels, levels of useful substances

Question 3

What are the two main poisonous waste products?

Answer 3

Carbon Dioxide and Urea

Question 4

Why must carbon dioxide be removed?

Answer 4

Because it mixes with fluid inside cells and creates acidic solutions that prevent enzymes from working

Question 5

Where does urea come from?

Answer 5

Extra amino acids in protein that cannot be used by the body are converted into urea.

Question 6

What is the function of the kidneys?

Answer 6

To remove waste products, a part of homeostasis.

Question 7

What can Kidneys filter out if it is needed?

Answer 7

Water and mineral ions

Question 8

What must Kidneys filter out?

Answer 8

Urea

Question 9

What are the main ways through which a person looses water?

Answer 9

Through sweat and breathing it out.

Question 10

Where is urea produced?

Answer 10

The liver

Question 11

What is a Ureter?

Answer 11

A tube connecting a kidney to the bladder.

Question 12

What is the Urethra?

Answer 12

The tube connecting the bladder to the sex organs.

Question 13

How do the kidneys work?

Answer 13

They completely filter the blood of everything, then re absorb everything the body needs.

Question 14

Why don’t blood cells enter the kidney tubules?

Answer 14

They are too big.

Question 15

How is sugar re-absorbed back into the bloodstream?

Answer 15

Active transport

Question 16

What are the two methods of treating kidney failure?

Answer 16

Dialysis (Artificial Kidney), or a Kidney transplant.

Question 17

What does Dialysis Fluid contain? Why is it important?

Answer 17

The same amount of useful substances as the blood. Therefore no net movement of useful substances occurs out of the blood.

Question 18

What does Dialysis Fluid not contain? Why is this important?

Answer 18

Urea. There will be a steep concentration gradient of urea between the dialysis fluid and the blood, so urea will diffuse out of the blood.

Question 19

What are the disadvantages of Dialysis?

Answer 19

You have to follow a very carefully controlled diet, and you have to spend a long time connected to the machine, many times a week.

Question 20

What is the main problem with transplanting kidneys or other organs?

Answer 20

Rejection as the anti-bodies of the recipient attack the anti-gens on the cells of the donor’s organ

Question 21

How is rejection combated?

Answer 21

Use of immuno suppressant drugs

Question 22

What is the disadvantage of using immuno suppressant drugs?

Answer 22

The body is less effective at fighting off diseases.

Question 23

Why does body temperature need to remain constant?

Answer 23

The function of enzymes and chemical reactions vary depending on it.

Question 24

How does the thermoregulatory center of the brain work?

Answer 24

It measures the temperature of blood passing through it, and adjusts the body accordingly.

Question 25

What does the body do to control temperature?

Answer 25

Sweat more/less, expand/contract capillaries and pull hair up or flat (although this does very little in humans) and shivering.

Question 26

What temperature does the body work at?

Answer 26

37 degrees C.

Question 27

Why does sweating cool a person?

Answer 27

Heat energy warms the sweat and causes it to evaporate, taking the heat energy with it.

Question 28

Why does shivering warm a person?

Answer 28

Causes muscles to contract and relax rapidly, releasing more thermal energy due to respiration.