[Verse 1] Down past the soma a cable uncoils, wrapped and insulated in waxy white foils The axon hillock is the ramp where the charge gets steep Then the initial segment, loaded with sodium gates to keep the pulse precise — that's the spark zone, dense and small Action potentials usually answer this very call [Chorus] One axon, one output line, hillock to initial segment, that's the starting sign Branches fork like creek beds, collaterals unfold, kinesin runs the errands out, dynein brings it home From a stub too short to measure to a meter-long relay, the cable keeps the message moving, never losing its way [Verse 2] Some axons stay close, barely longer than a grain, others stretch a whole meter, a marathon of strain Like the sciatic giant, running spine down to your toes, one single fiber wiring where the longest signal goes It splits along the journey into branching, leafless trees, each collateral a courier, delivering with ease [Chorus] One axon, one output line, hillock to initial segment, that's the starting sign Branches fork like creek beds, collaterals unfold, kinesin runs the errands out, dynein brings it home From a stub too short to measure to a meter-long relay, the cable keeps the message moving, never losing its way [Verse 3] Inside the shaft are microtubule tracks, straight and true, tiny motors walking cargo like a freight train pushing through Kinesin carries forward, called anterograde, away from base, dynein hauls the old parts back, retrograde, a homeward race Fast lanes clip two hundred, maybe four hundred millimeters a day, molecular movers never resting, never taking holiday [Bridge] A squid once lent its secret, a giant axon thick as string, a whole millimeter wide — researchers threaded everything They slipped a wire inside it, measured voltage, watched it climb, unlocked the action potential, one cephalopod at a time [Verse 4] Wrapped in sheaths of myelin, laid down segment by segment, oligodendrocytes and Schwann cells building out the pavement Between each sheath a gap appears, the node of Ranvier stands bare, where sodium channels cluster thick, renewing voltage there The signal doesn't crawl along, it leaps from node to node, saltatory conduction lights the fast electric road Lose the sheath and watch it stumble, slow and scattered, losing pace— that's the cost of demyelination, a stutter in the race [Chorus] One axon, one output line, hillock to initial segment, that's the starting sign Branches fork like creek beds, collaterals unfold, kinesin runs the errands out, dynein brings it home From a stub too short to measure to a meter-long relay, the cable keeps the message moving, never losing its way [Outro] Hillock, segment, sodium spark, kinesin out, dynein back through the dark One long cable, built to send, the axon's job: deliver to the end
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