Action Potential Flashcards
What is the value at which there is no net move of ions in the cell
-70mV
What is the value for K
At -94 millivolts no net K+ diffusion outside
What is the value for Na?
At +61 millivolt no net diffusion of Na+.
What is an action potential?
change in permeability of the membrane due to activation of voltage-gated channels which are inactive at rest state
-EMF- electromotive force?
The net driving forces for ion diffusion (electrical and chemical) inside and outside.
Cations- (Vdf>0) ___________
(Vdf<0) __________
outward, inward
Every cell has different ____________ value.
resting potentiala
Anions- (Vdf>0) ________
(Vdf<0) ______
inward, outward
____________________ for each ion tends to cause net movement of the ion across the membrane. This driving force is equal to the difference between the membrane potential (Vm) and the equilibrium potential of the ion (Veq)- Vdf = Vm – Veq
electrochemical driving force (Vdf)
-Equilibrium potential?
is the point at which there is no net movement of an ion into or out of a cell. It occurs when the concentration gradient of the ion is in balance with the electrical gradient of the ion
-At resting potential charge of cells is __________ inside and __________ outside
negative, positive
action potential has 3 stages:
1) resting stage - 70mV
2) Depolarization - electrical gradient raises until its positive (+35mV) aka hyperpolarization state. This is due to influx of sodium.
3) Repolarization - electrical gradient is lowered again until it reaches rest state (going through a -94mV, hyperpolarization state). The Na+ channels begin to close as the K+ channels open. Diffusion of K+ to the exterior re-establishes the normal negative resting membrane potential
-Voltage gated Na+ channel- has __ gates and __ stages. They can be at ___________________
2, 3 , rest, activated or inactivated.
At rest inactivated gate is opened and activated is close. Increase of voltage opens activation gate and closes inactivation gate. Activation gate recloses when the cell is back to rest state potential (-70mV). The activation gate opens quickly and it takes time for inactivation gate to close while sodium influx (depolarization).
-Voltage gated K+ channel- __ gate with __stages. Increase of voltage opens the gate (slow activation) approximately when Na+ channels become inactivated.
1, 2
what is the action potential activation treshold?
-50mV