Blood Pressure Regulation

[Intro] Ever wonder why it's two numbers and not one Something decides both of them every second and it never once asks you [Verse 1] Pressure is blood pushing out on the wall Every artery feels that force Cardiac output is what the heart sends Resistance is how tight the vessels squeeze Multiply those two and you've got pressure Move either one and the pressure moves [Pre-Chorus] Output is heart rate times stroke volume Resistance lives almost entirely in the radius Narrow the radius and resistance climbs Radius to the fourth power, hold onto that [Chorus] Output times resistance, that's pressure Heart rate times stroke volume gives you output Preload fills it, afterload fights it Contractility squeezes harder Radius to the fourth in the vessel Squeeze it a little, pressure jumps a lot [Verse 2] Pressure drops and the body catches it fast Baroreceptors sitting in the carotid sinus Sitting in the aortic arch reading the stretch Signal runs to the medulla in a heartbeat Sympathetic speeds it up and clamps the vessels Parasympathetic slows it through the vagus [Bridge] When it stays low the kidney steps in Renin wakes up angiotensinogen Lungs convert it to the form that constricts Aldosterone holds onto sodium and water [Chorus] Output times resistance, that's pressure Heart rate times stroke volume gives you output Preload fills it, afterload fights it Contractility squeezes harder Radius to the fourth in the vessel Squeeze it a little, pressure jumps a lot [Outro] Baroreceptors are fast, the kidney is slow Output is flow, radius is squeeze Preload fills, afterload resists Touch the radius and pressure moves the most [End]