Blood Pressure Regulation
The control of the pressure that drives blood through the vessels — high enough to reach every tissue, low enough not to damage the vessels or overwork the heart.
Fast control — the nervous system
Section titled “Fast control — the nervous system”Pressure sensors (baroreceptors) in major arteries report continuously to the brainstem, which adjusts within seconds by changing:
- the heart rate and force of the heartbeat, and
- the diameter of blood vessels — narrowing raises pressure, widening lowers it.
Slow control — hormones and the kidneys
Section titled “Slow control — hormones and the kidneys”Over minutes to days, blood pressure is set largely by blood volume, which the kidneys control by adjusting how much water and salt they keep or release. The RAAS and vasopressin systems are central here.
Key idea
Section titled “Key idea”Blood pressure is regulated on two timescales at once: a fast nervous reflex for moment-to-moment stability, and a slow hormonal–kidney system that sets the long-term baseline.