B12

Question 1

What is homeostasis?

Answer 1

Maintenance and control of our internal environment

Question 2

What is temperature controlled by?

Answer 2

Thermoregulatory centre in the hypothalamus

Question 3

How does the thermorugulatory centre control temperature?

Answer 3

Receptors that are sensitive to temp changes in the blood flowing through the brain.

Question 4

How to blood vessels cool the body down?

Answer 4

Skin capillaries widen(vasodilation) to bring more blood to skin.
Skin flushes and heat is lost by radiation and convection

Question 5

How does sweating cool the body down?

Answer 5

Sweat glands produce sweat which is secreted on the surface of the skin.
When it evaporates it removes heat from the skin

Question 6

What is sweat made up of?

Answer 6

Water
Salts
Urea

Question 7

How to blood vessels keep you warm?

Answer 7

Skin capillaries narrow to bring less blood to skin

This reduces heat loss by radiation

Question 8

How does shivering reduce heat loss?

Answer 8

Skeletal muscles contract and relax rapidly releasing heat due to respiration that happens

Question 9

Name 4 waste products

Answer 9

Carbon dioxide
Water
Mineral ion’s
Urea

Question 10

How is co2 removed from body?

Answer 10

1) CO2 diffuses out of respiring cells and into plasma
2) CO2 diffuses from plasma into alveoli
3) here it is exhaled by the respiratory system as a gas

Question 11

How is urea removed from the body?

Answer 11

1) urea diffuses from liver cells to plasma of blood
2) it is filtered out of the blood by the kidneys
3) removed from body as urine

Question 12

How are excess amino acids and protein removed?

Answer 12

1) converse into ammonia
2) converted from ammonia to urea 3) 3) 3) which can be safely removed by the body

Rest of amino acids converted to glucose then respired or stored

Question 13

What are the functions of the kidneys(3)

Answer 13

1) Removal of urea from blood
2) Removal of excess water and mineral ions from blood
3) conservation of water and mineral ions if In short supply

Question 14

How do the kidneys work (4)

Answer 14

1) all water,mineral ions,glucose and urea pass from the blood to the kidney
2) all glucose reabsorbed by diffusion and active transport
3) no urea reabsorbed
4) water and mineral ions are selectively reabsorbed

Question 15

What does ADH do?

Answer 15

Controls the amount of water reabsorbed from the kidney by making structures more permeable to water

Question 16

Explain the role of ADH when water balance is low? (5)

Answer 16

1) detected by receptors in hypothalamus
2) causes pituitary to secrete ADH
3) ADH travels to kidney via blood
4) ADH makes collecting ducts in the kidney permeable to water which increases rate of reabsorption
5) this produces a small volume of concentrated urine

Question 17

Explain the role of ADH when water balance is too high

Answer 17

1) detected by receptors in hypothalamus
2) causes pituitary to secrete less ADH
3) with less ADH less collecting ducts are permeable to water which decreases the rate of reabsorption back into blood
4) produces large volume of diluted urine

Question 18

2 effects of kidney damage

Answer 18

Build up of toxins

Cells damaged due to osmosis

Question 19

What is dialysis?

Answer 19

When a machine carries out the function of the kidney

All blood is passed through machine to get it cleaned

Question 20

How does dialysis work?

Answer 20

Blood flows between partially permeable membranes in the machine
On the other side of machine is dialysis fluid
Substances diffuse form blood to fluid and vice versa until concentrations are balanced

Question 21

How does an organ become rejected?

Answer 21

1) immune system recognises it as foreign and attacks it
2) antigens of cell surface membranes are not recognised by immune system
3) lymphocytes produce antibodies complimentary to antigens
4) antibodies bind and kidney cells are destroyed

Question 22

How does tissue matching reduce rejection?

Answer 22

Find a kidney with similar antigens to recipient

Question 23

How do immunosuppressant drugs reduce rejection?

Answer 23

They suppress the immune system and turn down its response.

Question 24

Disadvantage of immunosuppressants

Answer 24

They prevent patients from being able to deal with other infections