Topic overview

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MAP is determined by cardiac output and systemic vascular resistance, and can be estimated from diastolic pressure and pulse pressure. Rapid buffering comes from the baroreceptor reflex, which senses stretch in the carotid sinus and aortic arch and adjusts vagal and sympathetic activity. Chemoreceptors and the CNS ischemic response also contribute under particular conditions. Intermediate regulation involves hormones including angiotensin II, aldosterone, ADH, and natriuretic peptides. Over the longer term, the kidney–body fluid mechanism adjusts sodium and water balance to help normalize pressure. Local autoregulation, endothelial signals, sympathetic activity, and vascular stress-relaxation add further control. Together, these mechanisms explain how arterial pressure is defended while blood flow and fluid balance are adjusted.