Action Potential Flashcards
True or false
Action potential is a change in membrane potential resulting in
Repolarization followed by
Depolarization of membrane”
F
Brief reversal of membrane potential
occurs with a total amplitude of
100 mv
What are the Two types of channels involved
in action potential in a nerve
fiber
Voltage (k and na)
True or false
Voltage potassium channels are present in smooth muscles
True
Sodium and potassium channels Gates open or close in response
to a change in
Membrane potential i.e. voltage
……is that level of membrane
potential [MP] at which action potential is
inevitable.
Threshold
T or f
At threshold potential, net
inward current becomes larger than net
outward current
T
True or false
In resting state , the membrane is more premeable to k+
True
True or false
All Voltage-Gated Na+ and K+ channels are open
False
What gate of na channel open in resting state
Inactivation
What typa channel opena qhwn depolarization happen
Na channel(activation gates)
Depolarization is due to ?
Opening v-g na channel
At the end of depeloarization what gate of na channel closes
Inactivation gate
True or false
During undershoot
Na+ tries to take mp to its equilibrium potential
F. Overshoot
True or false
At the peak of AP, membrane is closest to Na+ equilibrium
potential
T
What causes downstroke in graph?
Positive charges leaving cell
Thus repolarization is caused by
an outward K+ current as well as stopping of Na+ influx
True or false
Repolarization and k efflux restore the resting ionic
conditions
False.Repolarization and K efflux
restores the resting electrical
conditions of the neuron only
Ionic redistribution back to
resting condition is restored by
the
sodium-potassium pump
True or false
During Resting state more K+ leaking out, less Na+ leaking in
True
Graded potential are produced by
Soma and dendrites
Graded potentials are produced in dendrites and soma due to
Opening of ligand gated channels
Action potential fires up at which region
in the region of initial segment rich in V-G Na+
The transmission of a depolarization process along a nerve fiber is called
Nerve impulse
When does voltage gated Ca++ channels open
When AP reaches axon terminal
Speed of propagation depends on
Myelination
Diameter
كلهم علاقتهم طردية
What type of impulse conducting is faster
Saltatory
“The time period during which another normal AP can
not be generated, no matter how strong is the stimulus.
“
This is a definition of?
Shows refractiry period
Whats this Diffention
Time from the opening of the Na+ activation gates (threshold) followed by closure of inactivation gates that enter a
closed, inactive state.
Absolute refractory period
True or false
In relative refactory period k+ gates are open and repolarization is occuring
True
Why in the relative refactory pitiontal the supra-threshold stimuli can open Na channels to cause AP
Cause The threshold level is elevated
the magnitude of ap is dependent upon
1-serum Na+ level
Refactory period
True or false
The action potential amplitude depends on strength
F. It follows all or none law
I cardiac and smooth muscles what ions enter the cell to produce depolarization
calcium
Affect of hyperkalemia on membrane
depolarization c
Hypokalemia affect on membrane
Hyperpolarizing
What happens when ca binds to na
stabilize the
electrical state of Na+ channels.
Whats the cause behind muscle tetany
Hypocakcemia
At the peak of AP, membrane is closest to …… equilibrium
potential
Na
