Sensory functions of the heart.

Stretch receptors are situated in the walls of the atria, left ventricle and coronary arteries. Atrial receptors are stimulated by atrial distension due to increased filling as the result, amongst other things, of an increased blood volume. Their reflex responses are increases in heart rate and in urine flow. Ventricular receptors may be stimulated by chemical agents, mechanical stimuli, or both. They are responsible for the Bezold-Jarisch reflex of bradycardia and hypotension, but their normal physiological role, if any, is uncertain. The proximal part of the left coronary artery contains baroreceptors which are excited by increases in blood pressure. Their role, like other baroreceptors, is to control blood pressure by regulation of the diameter of the peripheral blood vessels.