b12 - homeostaesis in action

Question 1

which two parts of the body have thermoreceptors?

Answer 1

• hypothalamus
• skin

Question 2

vasodilation of blood vessels

Answer 2

• capillaries get wider so a larger amount of blood can flow near the skin surface

Question 3

what happens when the temperature rises on a hot day?

Answer 3

1) vasodilation of the blood vessels
2) evaporation sweat - produced by the sweat glands and then is evaporated from the skin
3) no shivering
4) hairs and hair erector muscles are relaxed (no goosebumps)

Question 4

vasoconstriction of the blood vessels

Answer 4

• capillaries get smaller so less blood can flow near the skin surface. no energy is released

Question 5

where/how is urea produced?

Answer 5

deamination - removes the poisonous part of amino acid

Question 6

how is urea removed?

Answer 6

through the kidney via urine

Question 7

kidneys

Question 8

renal artery

Answer 8

brings deoxygenated blood containing urea and other substances

Question 9

renal vein

Answer 9

carries oxygenated blood away from the kidney once the urea and other substances have been removed from it

Question 10

ureter

Answer 10

tube that connects the kidneys and the bladder

Question 11

what happens when the temperature falls

Answer 11

1) vasoconstriction of blood vessels
2) no sweat produced
3) the body starts to shiver to produce heat for the body
4) hairs and hair erector muscles stand on end to trap air

Question 12

glomerulus

Answer 12

• acts as a filter to remove water and urea from deoxygenated blood

Question 13

nephron

Answer 13

each of the functional units in the kidney, consisting of a glomerulus and its associated tubule, through which the filtrate passes before emerging as urine

Question 14

why do kidneys have a large blood supply?

Answer 14

• all blood has toxins so the more blood filtered through, the better

Question 15

role of ADH (antidiuretic hormone) in water regulation - high/low ADH

Answer 15

HIGH ADH: increases permeability of kidney tubule - more water reabsorbed by the kidney so less urine

LOW ADH: decreases permeability of kidney tubule, less water reabsorbed by kidney, more urine

Question 16

maintaining a constant temperature - behavioural

Answer 16

• sweating - removing thermal energy
• goosebumps - hairs standing up to trap a layer of air
• shivering - muscle contractions which require energy

Question 17

optimum body temperature

Answer 17

37 degrees

Question 18

why do we want to maintain our body temperature?

Answer 18

if the internal temperature is too high, the enzymes may denature and will no longer be able to catalyse important reactions

Question 19

ultrafiltration

Answer 19

filters out ALL the small molecules (even the useful ones)

Question 20

selective reabsorption

Answer 20

sodium, amino acids and glucose (useful molecules) are then reabsorbed from the filtrate back into the blood

Question 21

how is carbon dioxide removed from the body?

Answer 21

via respiration

Question 22

how is urea removed from the body?

Answer 22

through the urine

Question 23

how is the water reabsorbed?

Answer 23

via osmosis (after selective reabsorption)

Question 24

why do red blood cells not get filtered out?

Answer 24

they’re too big to pass through the permeable membrane

Question 25

why is urea removed?

Answer 25

if it becomes too concentrated, it becomes poisonous

Question 26

why do kidneys have a large blood supply?

Answer 26

so that urea can removed from from as mush blood as possible

Question 27

how is glucose transported back into the blood?

Answer 27

diffusion and active transport

Question 28

what reaction in the body produces respiration

Answer 28

aerobic respiration

Question 29

maintaining water and mineral balance

Answer 29

your body has control over urea, excess water and mineral ions removed via kidneys but no control over how much water leaves the lungs and mineral ions and urea removed via the kidneys

Question 30

where is ADH produced?

Answer 30

the pituitary gland

Question 31

how is the amount of water in the blood is controlled by the kidneys

Answer 31

- pituitary gland - releases ADH - changes permeability of the nephron/ tubule - water reabsorbed

Question 32

problems with the kidneys

Answer 32

- damage due to injury - kidney failure - bacterial infections - polycystic kidneys (genetic)

Question 33

two types of treatment

Answer 33

- kidney dialysis - kidney transplant

Question 34

is there active transport in dialysis?

Answer 34

no, there isn't there is DIFFUSION

Question 35

what is in dialysis fluid?

Answer 35

water, glucose, ions - same conc as blood so a conc gradient can be maintained

Question 36

what is dialysis?

Answer 36

removal of waste/cystic product (nearly the same to the function of a kidney)

Question 37

why does the clean blood flow through a bubble trap?

Answer 37

a pocket of oxygen could lead to further damage eg. an aneurysm

Question 38

why are there blood thinners in the dialysis process?

Answer 38

to prevent clotting

Question 39

how does dialysis take place?

Answer 39

dialysis fluid carrying waste products and urea is removed via the use of a dialysis machine

Question 40

why is the glucose concentration in the dialysis fluid the same as its concentration in blood?

Answer 40

so that there is no net movement of glucose out of the blood via diffusion so that its concentration can be maintained

Question 41

how does dialysis ensure that the urea is removed?

Answer 41

no urea in the dialysis fluid ensures that there is a large concentration so diffusion will happen at a faster rate

Question 42

why is dialysis an option?/ what does it do?

Answer 42

it removes urea from the blood when the kidneys themselves cannot

Question 43

transplants and how they work

Answer 43

- donor needs to be the same blood group and tissue type as the recipient - can be a relative (who is alive) - or from a victim of an accident, stroke or heart attacks - involves operation (risks) - transplants may be rejected by the immune system - immunosuppressants - medicines given to suppress the immune system

Question 44

thermoregulatory centre

Answer 44

hypothalamus

Question 45

shivering

Answer 45

- causes the muscles to automatically contract - the process requires energy from respiration - respiration produces heat which warms us up

Question 46

sweating

Answer 46

- sweat glands release water, which covers the skin - heat energy is transferred to this water and once it reaches the surface of the skin, it evaporates - as it evaporates it takes the heat energy with it - hence cooling you down