Baroreflex

The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels.

The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes the heart rate to decrease.

The system relies on specialized neurons, known as baroreceptors, chiefly in the aortic arch and carotid sinuses, to monitor changes in blood pressure and relay them to the medulla oblongata.

Baroreflex-induced changes in blood pressure are mediated by both branches of the autonomic nervous system: the parasympathetic and sympathetic nerves.

Baroreceptor activity travels along these nerves directly into the central nervous system to excite glutamatergic neurons within the solitary nucleus (SN) in the brainstem.

[citation needed] Even at resting levels of blood pressure, arterial baroreceptor discharge activates SN neurons.

When blood pressure rises, the carotid and aortic sinuses are distended further, resulting in increased stretch and, therefore, a greater degree of activation of the baroreceptors.

[citation needed] The sympathetic and parasympathetic branches of the autonomic nervous system have opposing effects on blood pressure.

[citation needed] By coupling sympathetic inhibition and parasympathetic activation, the baroreflex maximizes blood pressure reduction.

[citation needed] The baroreflex may be responsible for a part of the low-frequency component of heart rate variability, the so-called Mayer waves, at 0.1 Hz.

[citation needed] One trial[6] has already shown that baroreflex activation therapy improves functional status, quality of life, exercise capacity and N-terminal pro-brain natriuretic peptide.