B12

Question 1

thermoregulatory system

Answer 1

body temp is controlled by the thermoregulatory centre in the brain
contains receptors sensitive to the blood

Question 2

skin

Answer 2

contains temperature receptors and sends nerve impulses to the thermoregulatory centre

Question 3

cooling down the body

Answer 3

• body temp too high
• blood vessels dilate
  -sweat is produced from sweat glands
• cause a transfer of energy from he skin to the environment

Question 4

keeping warm

Answer 4

• body temp too low
• blood vessels constrict
• sweating stops
• reducing transfer if energy to the environment

Question 5

shivering

Answer 5

• skeletal muscles contract
• exothermic reactions of respiration needed
• muscle contraction
• raises temperature

Question 6

waste products

Answer 6

• water leaves the body via the lungs during exhalation
• water, mineral ions and urea are lost through the skin in sweat
• there is no control over these

Question 7

carbon dioxide waste

Answer 7

carbon dioxide produced in respiration must be removed because dissolved carbon dioxide produces an acid which effects enzymes working

Question 8

urea waste

Answer 8

removed via the kidneys in the urine. Loss of water and mineral ions is carefully balanced in the body

Question 9

functions of the kidneys

Answer 9

important for excretion and homeostasis

Question 10

how kidneys work

Answer 10

• produces urine by filtering the blood
• then reabsorbs all of the glucose, mineral ions and water needed by the body
• excess mineral ions, urea and water are removed in urine

Question 11

water balance

Answer 11

• maintained by hormone ADH
• if blood becomes too concentrated pituitary gland releases ADH into blood
• changes the amount of water reabsorbed by the kidney tubules

Question 12

kidney failure treatment

Answer 12

• regular sessions of dialysis
• kidney transplant

Question 13

dialysis

Answer 13

• function of the kidneys is carried out artificially
• in dialysis machine the concentration of dissolved substances in the blood is restored to normal levels

Question 14

how dialysis works

Answer 14

the level of useful substances in the blood are maintained, while urea and excess mineral ions pass from the blood into the dialysis fluid

Question 15

disadvantages of dialysis

Answer 15

• controlled diet
• regular sessions
• feel tired, unwell

Question 16

kidney transplants

Answer 16

a healthy kidney from a donor replaces the function of the diseased or damaged kidney

Question 17

rejection problem

Answer 17

• antigens of donor are different to antigens of recipient
• risk antibodies of immune system of recipient will attack antigens of donor organ
• results in rejection and destruction of kidney

Question 18

preventing rejection

Answer 18

• tissue types of donor and recipient are matched closely as possible
• immunosuppressant drugs are used

Question 19

dialysis or transplant

Answer 19

• dialysis more available
• dialysis has lots of disadvantages
• dialysis is more expensive
• transplant means free from restrictions
• have to take drugs every day
• risk of rejection