Baroreceptors


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Baroreceptors

 

(baroceptors, mechanoreceptors, and pressoreceptors), sensory nerve terminals in blood vessels that perceive changes in blood pressure and reflexly regulate its level. Baroreceptors become stimulated when the walls of the vessels distend. They are found in all vessels but are concentrated mainly in reflexogenic zones (such as cardiac, aortic, carotid sinus, and pulmonary). When blood pressure rises, baroreceptors send impulses to the central nervous system that decrease the tonus of the vascular center and excite the central formations of the parasympathetic division of the autonomic nervous system, and result in a lowering of the pressure. After a frequent and prolonged rise in blood pressure, the baroreceptors adapt to it and thereby may be one of the causes of hypertension.

G. N. KASSIL’

References in periodicals archive ?
The physiological mechanisms responsible for PEH were not analyzed in the present study; however, some studies (7,31) suggest that the hypotensive response is caused by baroreceptor action, reduced total peripheral vascular resistance, and decreased cardiac output.
References [42,43] illustrate the dynamics of different firing patterns and the frequency and temporal coding mechanisms of aortic baroreceptor.
The MobiusHD System capitalises on the ability of the body's baroreceptor mechanism to regulate blood pressure.
The baroreflex arc is composed of multiple neural components including the aortic and carotid baroreceptors, the nucleus tractus solitarius (NTS), paraventricular nucleus of the hypothalamus (PVN), nucleus ambiguus (NA), caudal ventrolateral medulla (CVLM), and rostral ventrolateral medulla (RVLM) [16-19].
Denervation of baroreceptors leads to an inability of the receptors to alter systemic BP in response to various physiological stimuli; hence, hypertension following CEA coupled with baroreceptor reflex breakdown can result in cerebral hyperperfusion.
This decrease in the systemic vascular resistance causes reflex increase in the sympathetic activity, which is mediated by the baroreceptors present in the carotid sinus and aortic arch, thereby causing an increase in the heart rate.
In terms of the second theory a change in blood pressure is sensed by arterial baroreceptors, resulting in heart rate adjustment through the central nervous system and via also the fast vagal action and the slower sympathetic action.
The patient's sympathetic nervous system responded to inadequate blood supply, with baroreceptors in the arteries detecting the low pressure, causing the adrenal glands to release adrenaline and noradrenaline.
Experimental evidence has suggested that the DA neurons may be regulated by input from arterials baroreceptors. (3,32,33) This proposition is based on the finding that denervation of arterial baroreceptors caused decrease in dopamine content and in the activity of dopamine biosynthetic enzyme tyrosine hydroxylase in the striatum part of the VTA.
The patient's sympathetic nervous system responded to inadequate blood supply by her baroreceptors in the arteries, detecting the low pressure, and causing the adrenal glands to release adrenaline and noradrenaline.
With the use of existing experimental data of the aging human aorta, the researchers were also able to find how the stiffening of the aorta with age causes the baroreceptors to misinform the central nervous system about blood pressure.