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Etymology: L, reflectere, to bend back
a neural mechanism that automatically increases or reduces the heart rate. Stimulation of stretch receptors in the right side of the heart by increased venous return increases the heart rate, whereas increased arterial blood pressure stimulates nerve endings in the carotid sinus and aortic arch to reduce the heart rate.
An involuntary response consisting of a change in cardiac rate. Stimulation of sensory nerve endings in the wall of the carotid sinus by increased arterial blood pressure reflexively slows the heart (Marey law). Stimulation of vagus fibers in the right side of the heart by increased venous return reflexively increases the heart rate (Bainbridge reflex).
See also: reflex