nerve impulses Flashcards
what is the resting potential volatge
-70
why is this
because their are more positively charged ions on the outside of the neurone
what is resting potential
the potential differance across the membrane while the neurone is at rest.
during resting potential how is the potential difference altered
na+ and k+ pump at 3na+ out of the cell and 2k+into cell
what does this result in
there fore their is a higher concentration of Na+ outside and more k+ inside
what does this cuase the na+ and k= ions to do
na+ diffuses in and k+ diffuses out
however why does the inner membrane remane more negative - -70
because more Na+ channels are closed and the plasma membrane is more permeable to k+ ions
how is resting potential maintained
through the sodium potassium pump
what does this require
ATP
what does the sodium potassium pump do
sodium potassium pump moves 3 na+ ions outside the cell and two k+ ions to the inside of the cell
if k+ move into the nerve cell how come the resting is - 70
because the k+ ions have moved in it creates a concentration gradient of pottassium ions inside the cell and so k+ ions diffuse out the neuron creating a negative resting potential
why do sodium ions not just diffuse back through
sodium potassium pump becomes less permeable to na+ ions so they cant be transported
what causes the start of action potential
when a stimulus is received by the receptors
what does this change in stimulus cause
sodium channels open so more Na+ ions diffuse through
what does this cause
depolarization
what is depolerisation
when the inside of the neuron becomes more positively charged
what is the threshold potential
-50v
what happens if depolerization reaches -50v
more voltage gated sodium ion channels are opened- higher influx
what does this cause the action [potential to change to
+40v
after depolerization occours what happens
repolerisation
what is repolerisation
the potential of the neurone is returning back to a negative state
how does repolerization occour
more voltage gated k+ channels open and k+ ions leave the neuron
when most of the potassium ions leave the neuron what does this cause
hyperpolerization
what is hyperpolerisation
when the charge of the neuron drops bellow its resting
