Action potential Flashcards
resting state
inside of the neurone is more negatively charged than the outside of the neurone
potential difference
difference in charge
how is the resting potential maintained ?
sodium-potassium pumps in the neurone membrane
sodium-potassium pumps
three na+ ions are transported out of the neurone for every two k+ ions that are transported in .
sodium-potassium pumps
three na+ ions are transported out of the neurone for every two k+ ions that are transported in . leads to a build up of positive ions outside the cell
potassium ion channels
potassium ion channels in the neurone means its permeable to k+ ions
what happens to na+ ions (potassium channels)
becomes impermeable to na+ ions so the ions cannot diffuse back in the cell once they have been transported out /
resting potential (mv)
-70mv
order
- stimulation
- depolarisation
- all or nothing
- repolarisation
- hyperpolarisation
- resting potential
order
- stimulation
- depolarisation
- all or nothing
- repolarisation
- hyperpolarisation
- resting potential
stimulation
na+ channels open and flood into the neurone. potential difference becomes positive inside the neurone
depolarisation
potential increases above the threshold value (-55mv) membrane becomes depolarised. sodium channels open potential differnce becomes 30mv
all or nothing
if potential difference reaches threshold depolarisation will take place.if stimulus is stronger action potentials produce more frequently but size stays the same .
repolarisation
neurone is 30mv sodium ion channels close and potassium ions channels open. na+ ions transport back and potential differnce becomes more negative .
hyperpolarisation
prevents the neurone from being re-stimulated (refractory period)
