Baroreceptor reflex and long-term regulation of blood pressure
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Definition
Baroreceptor reflex (baroreflex, sino-aortic reflex): a rapid neural reflex from carotid sinus and aortic arch stretch receptors that corrects blood pressure within seconds.
It is the principal short-term mechanism of BP regulation, operating over 50 to 200 mmHg.
Receptors and Afferent Pathway
Baroreceptors are stretch receptors in the carotid sinus and aortic arch wall; a BP rise stimulates them, a fall reduces it.
Afferents: glossopharyngeal nerve (IX) from the carotid sinus; vagus nerve (X) from the aortic arch.
Baroreceptors are branched, knobby, myelinated terminals and are high-pressure receptors (arterial side).
Distinct from low-pressure (cardiopulmonary) baroreceptors in the atria and pulmonary circulation.
IX branch (carotid sinus): the carotid sinus nerve (buffer nerve).
X branch (aortic arch): the aortic nerve, a distinct branch of vagus only in the rabbit.