[Verse 1] Start the clock in the vena cava, dark tide rolling in, Low on oxygen, tired blood clocking back to kin, Right atrium opens like a lobby door, Thin-walled chamber priming for the tricuspid tour. Tricuspid flaps swing, three little sails, Cell slides through before the pressure prevails, Right ventricle grips it, thick-walled, quick, Loads the plunger for the pulmonic kick. [Chorus] Cava, atrium, tricuspid gate, Ventricle pumps it to the pulmonic straight, Lungs light it up, pulmonary vein sings home, Left atrium, mitral door, ventricle roams, Aortic valve opens, aorta's the road, Ten stations, one cell, carrying the load, Trace it, trace it, round the double track, Systemic goes out, pulmonary comes back. [Verse 2] Pulmonic valve — three cusps, a springboard cue, Shoots the cell to the lungs, old air traded for new, Alveoli whisper, carbon dioxide's the toll, Oxygen climbs aboard, that swap is the whole goal, Pulmonary vein — the only vein running bright red, Carries the fresh cargo to the left atrium bed, Small room, big job, station number eight, Mitral valve waiting, bicuspid, don't be late. [Chorus] Cava, atrium, tricuspid gate, Ventricle pumps it to the pulmonic straight, Lungs light it up, pulmonary vein sings home, Left atrium, mitral door, ventricle roams, Aortic valve opens, aorta's the road, Ten stations, one cell, carrying the load, Trace it, trace it, round the double track, Systemic goes out, pulmonary comes back. [Verse 3] Left ventricle's the powerhouse, walls thick as a fort, Squeezes with a force that could clear out a port, Aortic valve springs — cusps numbering three, Aorta's the highway, the cell rides free, Down through the body, organs sipping the tide, Capillary beds where the oxygen's supplied, Back to the vena cava, station ten complete, The loop closes quiet, then the pump beats repeat. [Verse 4] Zoom out further, feel the rhythm's design, Diastole fills soft, systole draws the line, SA node sparks it, the heart's own drummer boy, Signal rolls through atria, ventricles employ, AV node holds a beat, lets the chambers sync, Purkinje fibers flash quick as a blink, Every squeeze is timed, every valve on cue, The whole circuit dances, one continuous view. [Bridge – Quiz] Pop quiz, pop quiz — mitral valve springs a leak, What happens downstream when that seal turns weak? Backflow to the atrium, pressure starts to climb, Lungs get flooded — call it edema time. Now flip it: tricuspid's leaking on the right, Liver swells thick, ankles puff overnight. Every valve's a checkpoint, every leak tells a tale, Read the current backward, or the whole map derails. [Outro] Ten stations, one red cell, the map inside your chest, Trace it forward, trace it back — now you've passed the test.
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