[Verse 1]
Picture a wall built of fat and of gate,
Sodium outside, piling up, impatient to wait,
Potassium's crowded on the inner side of town,
Leak channels crack the door, letting potassium down,
Each ion that slips through leaves a charge in its wake,
Inside turns negative — seventy millivolts, that's the stake,
Not dead, not firing, just coiled and quiescent,
A held breath of voltage, patient and present.
[Chorus]
Negative seventy, that's the resting line,
Three sodium out, two potassium in — our pump keeps time,
Potassium leaks, leaves the inside in debt,
That's the battery charged, the cell's not finished yet,
Negative seventy, whisper it, know it,
The voltage is waiting, the membrane will show it.
[Verse 2]
Meet the sodium-potassium pump, tireless and small,
Burning a packet of ATP to work the wall,
Three sodium shoved out for every two K brought home,
An unequal trade that builds a voltage dome,
It's electrogenic — a pump that tips the scale,
Net charge marching outward makes the inside pale,
Do this a billion times a second, cell by cell,
And the gradient you get rings like a tiny bell.
[Chorus]
Negative seventy, that's the resting line,
Three sodium out, two potassium in — our pump keeps time,
Potassium leaks, leaves the inside in debt,
That's the battery charged, the cell's not finished yet,
Negative seventy, whisper it, know it,
The voltage is waiting, the membrane will show it.
[Verse 3]
Now Nernst walks in with a slide rule and a question,
Where would each ion rest, with no outside suggestion?
For potassium alone, the answer's ninety below,
For sodium alone, it's sixty high, you know,
Equilibrium's the hush where push and pull are matched,
Where hunger to diffuse meets the voltage it's attached,
But the cell's not pure — it's open, give and take,
So neither number alone explains the shape we make.
[Bridge]
Enter Goldman, weighing permeabilities with care,
Mostly potassium's voice is the loudest in the air,
Blend in whispers of sodium, a little chloride song,
Average them by how open every gateway is along,
Out comes seventy negative, the number we can trust,
The sum of every leak and pump, exact and never just a guess.
[Chorus]
Negative seventy, that's the resting line,
Three sodium out, two potassium in — our pump keeps time,
Potassium leaks, leaves the inside in debt,
That's the battery charged, the cell's not finished yet,
Negative seventy, whisper it, know it,
The voltage is waiting, the membrane will show it.
[Outro]
Quiescent, charged, and ready to spark,
Every thought that you have starts here in the dark,
Hold that number, seventy down inside,
The battery's set — now let the signal ride.