Cardiovascular system: hemodynamics, blood pressure regulation
Physiology · MBBS
Study notes
A patient stands up fast, feels dizzy, but recovers in seconds. Standing pools blood in the legs, dropping pressure — baroreceptors in the carotid sinus detect the fall instantly and fire less; the brainstem answers with sympathetic surge: heart beats faster and stronger, vessels constrict — pressure restored in seconds (the baroreceptor reflex). When this reflex is sluggish (dehydration, some drugs, autonomic disease), dizziness or fainting on standing (orthostatic hypotension) results.
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