How does the baroreceptor reflex explain the decrease in HR

How does the baroreceptor reflex explain the decrease in HR during “carotid sinus massage”?

Solution

Baro receptors are abundant in -a. wall of each internal carotid artery

                                                   b. wall of aortic arch

carotid baroreceptors are transmitted through small hering nerves to glossopharyngealnerves in the high neck and then to tractus solitarius in the medullary area of brain stem. signals from the aortic sinus is transmitted by vagus nerve to same tractus solitarius in medulla.

these together work as a baroreceptor reflex

on caarotid masage, the stretch receptor in arterial wall give a baroreceptor signal which goes to tractus solitarius. secomdary signals generated which inhibit the vasoconstrictor centre of the medulla and excite the vagal parasympathetic centre. the net effects are

- vasodilation of the veins and arterioles through out the peripheral system

- decreased heart rate and decreased cardiac contractility