Resting membane potential and acrion potential Flashcards
what does selective permemabiy of the membrane mean
it generates resting membrane poteintal
what is the voltage charge across a cell membrane
-50 to -90
what does the difference in ions across the plasma membrane result in>
generates RMP
what does diffusion do in the memrbane?
establish membrane potential
what does active t do in the membrane
maintains it
describe the leaky boat example?
K+ leaks out, Na+ seeps in
Na+K+ pump bails Na+ out and K+ in
Rate of active transport =rate of Na+ diffusion
why the changing of the rmp important?
Changes in RMP allow neurons to receive process & send information
how does the rmp change?
Alteration of ion concentration
Alteration of membrane permeability
describe a graded portential?
Usually incoming
Short distances
Variable strength
Action Potentials describe?
Long distance
Same stregth
what happens in depolarisation?
decrease in membrane potential
less negatvie
-70 to -65mv
what happens in hypoerpolarisation?
increase in membrane potential and is more negative
-70 to -75
what is a temporal summation?
rapid sucession of stimuli
what is spatial summation?
differnet sources of stimuli
what causes depolirsation?
sodium flowing into the cell
what causes repolirsation?
caused by k+ flowing out of the cek
what causes hyperpolirsation?
caused by k+ continiung to leave the cell
what happens in rapid depolrisation?
voltage gates sodium and pottassium have activation gates
a stimuuus finally reaches it which cause the threshold to go to -55mv
the gates now open +ve feedback
what happens in hypoerpolarisation?
increase in k+ permemability last longer than required
the sodium and potassium pump back to resting membrane potential
what is the refactory period
time interval during and after an action potential when a neuron or muscle cell is temporarily unable to generate another action potential in response to a stimulus.
what happens in an absolute rf
all sodium channels open or inactive
what happens in a relative rf
increase threshld for an AP and a 2nd ap is potential
Period of reduced excitability
during AP
immedialtey after AP
what is the good thing about a RF
enforces one way tranmission of AP
how do AP travel?
Na+ influx in specific region
Depolarisation of region
Adjacent current flow
VG-Na+ channels open in adjacent region
explain the propagation of a non myelinated axon?
Na+ influx in specific region
Depolarisation of region
Adjacent current flow
VG-Na+ channels open in adjacent region
Process continues along entire length of axon
Self-propagating
Refractory period drives forward direction
what does a myelinated popgation allow?
saltatoru conduction
graded potentials are …
Graded potentials are below the subthreshold but can summate to initiate action potentials.
