Resting Membrane Action Potentials Flashcards
what must occur to do any kind of activity voluntary and involuntary
Transmission of Signals
what must exist so signals may be sent to any cells
Electrical Potential
what happens when Electrical Potential is achieved
Electrochemical impulses are generated which carry signals to cells
This is the potential difference between intracellular and Extracellular fluid
Membrane potential
Two types of Membrane Potential
- Resting Membrane P
- Action P
Rapid changes in the membrane spreading along the nerve fiber
Action Potential membrane
Cells are at rest, no change is happening
no net charge
RMP
When there is an concentration gradiant
there is an electrical difference
this is the main force responsible for the establishing of the concentration K+ and Na+
Sodium potassium pump
this is higher intercellularly
Ka+
this is higher Extracellularly
Na+
how to equalize the concentration
K+ moves out thru Potassium leak channels
what happens when K+ moves out to the outer membrane from the cyptoplasm
outer membrane- electro positive
cytoplasm- Electronegative
how does the K+ go back in
the accumulation of anions attract Ka+ in
What is the RMP of the large nerve Fiber
-90MV
this is the Exact point of K* moving is the same of K+ moving back in
Equilibrium Nerst Potential
what is the MV of Ka+
.94mv is needed to attarct Ka+
Mv of NA+
+61mV
how do you obtain nerst potential or what equation do you use to obtain nerst
Nernst Equation
this equation is used to get all the ions involved
Goldman Equation
How do you get the -90mv of the large nerve
get all the mv of ions using the goldman equation.
this equation if also put in the goldman eq.
Nernst equation
what is the result when nersnt equation is put in goldman Eq.
you find the -.86mv = it’s the potential inside the membrane
Rmp is -90mv
what happens to the -4?
-4 comes from the NaK pump
it adds additional negativity inside
significance of RMP
- basic Cell to cell communication
- keeps cells ready for Action potential
- RMP is the driving force for ions to enter cells
What is the movement of ACTION POTENTIAL
unidirectionals
where does the nerve signal arise during acition potential
1st node of Ranvier and Axon Hilock
how does Action Potential work. what happens during AP
Rapid change of normal resting negative membrane to positive potential.
ends equally rapidly
Initiation of Action Potential
- Stimulus triggers RMP
- cell becomes permeable NA+
- NA+ enter cells
- cell reaches THRESHOLD POTENTIAL (-55)
- if -55 is not reached no AP
what is the MV of Threshold Potential of large nerves
-55mv
integral membrane proteins that change conformation in response to depolarization of the membrane potential, open a transmembrane pore, and conduct sodium ions inward to initiate and propagate action potentials
VOLTAGE-GATED SODIUM CHANNEL
2 gates of Voltage gated Sodium Channel
- Activation gate
- inactivation gate
this gate is towards the outside the cell
Activation gate
this gate is towards the inside
inactivation gate
3 stages of voltage gated sodium channel
- Resting stage
- Activated stage
- inactivated stage
this stage of volted gated stage NA - ions can no longer enter channels and repolarization is occuring
Inactivated stage
+35 to -90mv
this stage of volted gated stage NA - membrane is at -90
activation gate is closed so no influx is happening
Resting stage
this stage of volted gated stage NA - -90 to +35
opening of activation gate abd influx of Na ions making the channel more positive
Activated stage
are transmembrane channels responsible for returning the depolarized cell to a resting state after each nerve impulse
VOLTAGE-GATED POTASSIUM CHANNEL
2 stages of Voltage gated K+ channels
- Resting stage
- slow activation stage
this stage of voltage of is at -90mv. preventing efflux of K+
Resting stage
this stage of voltage of is at K+ is fully open and Na+ is closing
Slow activation stage
Stages of Action potential
- Resting stage
- Depolarization
- Repolarization
- hyperpolarization
- Recovery
2 ion channels
Sodium channel
potassium channel
Action potential stage where - Na+ channe closes and K channels open
goes back to normal resting membrane
Repolarization
Action potential stage where - excess exit of K+ and membrane will be more negative than RMP
Hyperpolarization
Action potential stage where - resting membrane before the AP begins. polarized at this stage and -70
Resting stage
Action potential stage where - membrane become more permeable to NA+ hence more positive and -70mv is neutralized
Depolarization
what happens when excess NA go into Large nerves
it goes in and overshoots near or beyond zero and becomes positive
what happens when excess NA goes into small fibers
it goes to 0 and does not overshoot
Action potential stage where - ions go back to normal. refractory period
Recovery
this is transmission of depolarization along a nerve or fiber
Impulse
characteristics of Action Potentials
- All or nothing
- Absolute refractory period
- Relative Refractory period
this characteristic of Ap. process will travel only if conditions are right
action potential must be higher or equal to threshold to proceed
All or nothing principle
this characteristic of Ap. starts at start of AP (Upstroke) until repolarization (downstroke)
- 2nd ap will not occure
- NA channels will be inhibited and membrane must return to RMP
Absolute Refractory period
this characteristic of Ap. Rmp is attained at Hyperpolarization
- stimulus must be greater than threshold but energy will be less
Relative Refractory period
2 types of transmission of nerve impulses
- Non saltatory
- Saltatory conduction
this is the continous conduction
- charges will leak
and decrease in charge
AP will stop
Non Saltatory Conduction
this type of nerve transmission travels from node to node
myelin sheaths prevent leakages
enables transmit effectively
Saltatory conduction
this nerve transmission has small nerve fiber
no myelin sheaths and velocity at 0.25
non saltatory
this nerve transmission has large nerve fiber
with mylein sheaths and 100 velocity
Saltatory conduction
