Neuronal Action Potential
Neuronal Action Potential
To the tune of “Wait For It” from Hamilton
[Verse 1]
A neuron rests at negative seventy millivolts
Low enough to keep the voltage-gated channels closed
A summation of potentials
Brings the axon to threshold
The sodium channels open
And here we go
[Chorus 1]
The depolarization phase
Sodium influxes with haste, and with haste, and with haste, and with haste
It wants to equilibrate
As dictated by the variables in the Nernst equation
If there’s a reason potential climbs, and voltage continues to rise
It’s the electrochemical gradient, the electrochemical gradient
[Verse 2]
Sodium channels shut their inactivation gate
An additional stimulus cannot generate
Another action potential
Sodium cannot cross the membranes
Potassium channels open
And the voltage will change
[Chorus 2]
The repolarization phase
Potassium effluxes with haste, with haste, and with haste, and with haste
It wants to equilibrate
As dictated by the variables in the Nernst equation
If there’s a reason for this at all, as voltage continues to fall
It’s the electrochemical gradient, the electrochemical gradient
[Bridge]
(Gradient, gradient, gradient, gradient)
Myelination increases potential speed
Schwann cells offer the insulation we need
The action potential can hop from node to node
Enough current to bring the next one to threshold
Action potentials, they are “all or none”
Stimulus intensity, recorded by frequency
Balance restored by the sodium-potassium pump
In a process requiring ATP
[Chorus 3]
The hyperpolarization phase
Potassium effluxes with haste, and with haste, and with haste, and with haste
It wants to equilibrate
Potential will change, fall below the resting membrane
If there’s a reason for this at all, as voltage continues to fall
It’s the electrochemical gradient, the electrochemical gradient
[Chorus 4]
Action potentials stimulate
Cells that neurons innervate so that they will respond to change
Reproducible in shape
The cycle does not change, for the same ions permeate
And if there’s a reason for all of this, one must exist
It’s the electrochemical gradient, the electrochemical gradient
