6.5 Homeostasis Flashcards
why do we need to keep our pH constant
pH affects the ammount of hydrogen ions and this can cause the tertiary structure of an enzyme to change, denaturing of an enzyme changing thr active site, preventing enzyme-substrate complexes and chemical reactions
why do we need to keep our temperature constant
low temp=little kinetic energy so chemical reactions involving enzymes slow down
high temp= too much kinetic energy, enzymes denature due to H,ionic and disulphide bonds breaking, changing the active site and preventing E-S complexes forming and therefore chemical reactions happening
why do we need to keep our water potential constant
too little water in the blood = blood having a lower wp than our tissue fluid. water will move by osmosis into our blood and this causes tissues to dehydrate
too much water in blood = water will have a higher wp therefore water will move into the tissue and not return, causing swelling
binding of insulin lead to an increase in rate of respiration in cells.
explain why (2)
insulin leads to more channel proteins for glucose
therefore more glucose enters cell for respiration
explain how insulin lowers the concentration of blood glucose (3)
insulin binds to receptors on liver/muscle cells
this causes more carrier/ channel proteins to become active
glucose diffuses into cells
enzymes in cells convert glucose to glycogen
people with type 2 diabetes have cells which do not respond to insulin. explain how this leads to a reduced ability to regulate blood glucose control (3)
fewer receptors on cell membrane
so fewer glucose transporter molecules
so less glucose can diffuse into cell and be converted to glycogen
during a glucose tolerance test the person remains at rest. why is it important that the person remains at rest? (2)
movement uses muscles
movement increases rate of respiration
therefore more glucose is used up
stimulation of osmoreceptors can lead to secretion of ADH. describe and explain how secretion of ADH affects urine produced by the kidneys (4)
permeability of membrane is increased
therefore more water absorbed from collecting duct
meaning a smaller volume of urine is produced
urine becomes more concentrated due to less water in it
explain how urea is concentrated in the filtrate (3)
water is reabsorbed by osmosis in decending loop of henle
active transport of ions creates a water potential gradient to allow water to leave
explain the role of the loop of henle in the absorbtion of water from the filtrate (6)
in the decending limb of the loop of henle, water leaves by the limb by osmosis due to a low water potential in the medulla compared to inside the limb
to create this wp gradient, sodium ions are actively transported out of the accending loop
accending limb impermeable to water
further down loop of henle the lower the wp in the loop of henle
water leaves collecting duct by osmosis
describe how ultra filtration produces glomerular filtrate (5)
high hydrostatic pressure forces small molecules eg. water, ions and amino acids out of capillaries
through basement membrane then podocytes
proteins that are too large stay in blood
homeostasis
the maintenance of a constant internal environment
ways in which water is removed from the body
via the kidneys
sweating
breathing
explain how a large increase in a persons body temperature can cause harm
enzymes denatured altering tertiary structure. preventing E-S
preventing hydrolysis of carbs (or any other example)
negative feedback
where a change triggers a response which reduces the effect of a change
