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I know that pressure is sensed in the skin by mechanoreception mediated by skin receptors. Static pressure stimuli are mainly sensed by slow-adapting fibers connected to receptors like the Merkel discs. Vibratory stimuli are sensed by rapidly adapting receptors like the Pacinian corpuscle.

Blood pressure is also sensed by the body and the brain regulates blood pressure by influencing the peripheral nervous system that can increase or decrease the blood output of the heart.

How are blood pressure differences in the brain sensed and how do these receptors mediate cardiac activity? Are blood pressure differences in the brain sensed by rapidly adapting receptors akin to Pacinian corpuscles?

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    $\begingroup$ I've added background to the question and I vote to re-open. $\endgroup$ – AliceD Mar 29 '17 at 18:36
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Blood pressure is sensed in blood vessels by baroreceptors. Baroreceptors are stretch-sensitive nerve fibers located primarily in the aortic arch and carotid sinuses. The baroreceptors send afferent fibers via the glossopharyngeal nerve to the nucleus tractus solitarii in the dorsal medulla in the brainstem. From there, efferent cardiovascular neurons send projections to the medulla and spinal cord. There are also stretch-sensitive receptors in the heart and pulmonary vessels, called cardiopulmonary receptors that use the same nerural connections as the baroreceptors.

The baroreflex loop results in activation of sympathetic or parasympathetic fibers to the heart, the smooth muscle of the peripheral blood vessels, and other organs such as the kidney to maintain arterial pressure at normal levels.

In a simplified scheme, increased pressure stimulates baroreceptors, which attenuates the sympathetic outflow to the peripheral vessels and the heart, restoring pressure to normal levels. The parasympathetic influence will dominate which is mediated by acetylcholine. Conversely, a decrease in pressure relieves the baroreceptors and increases sympathetic outflow. Sympathetic activation causes a release of noradrenaline that leads to vasoconstriction and increased cardiac output and hence an increased blood pressure (see Fig. 1).

conrol of blood pressure
Fig. 1. Control of blood pressure. Source: Human Physiology (2011).

Reference
- Cougias et al., Med Sci Monit (2010); 16(1): RA1–RA8

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    $\begingroup$ With regard to blood pressure in the brain, note that besides the general baroreceptor in the aorta at the output of the heart, there are two at the carotid sinuses. The latter are in the neck just under the head and sense the pressure of the blood flowing into the head, providing close control of the blood pressure in the brain. $\endgroup$ – mgkrebbs Feb 10 '16 at 3:20
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The control mechanism in the brain for blood pressure is a endocrine hormone named ADH. This stands for AntiDiuretic Hormone. This hormone is produced by special nerves in the hypothalamus and stored in the posterior pituitary gland. ADH is stimulated by increased blood solute (particles like ions and other molecules) present or decreased blood volume level. When you have adequate hydration, this hormone is actually inhibited. On a very elementary level, it works by stimulating kidney tubule cells to reabsorb water rather than eliminate it. Some drugs also interfere with ADH, most commonly ethanol (drinking alcohol).

Edit: Forgot to add that ADH is also known as Vasopressin, and is also responsible for constricting the blood vessels.

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    $\begingroup$ Although AVP may affect blood pressure (does it?), its primary role is in fluid balance by affecting kidney function. And if EtOH affects AVP, it should also affect blood pressure according to your reasoning? Could you add some references to back your answer up? I don't buy it :-) $\endgroup$ – AliceD Feb 9 '16 at 20:06
  • $\begingroup$ Fluid balance is the primary regulator of blood pressure. EtOH most definitely affects blood pressure, as it is a CNS depressant. ADH is also known as vasopressin, and is the main control for blood fluid, and solute levels which in turn is responsible for the mineralcorticoids (renin-angiotensin) synthesized in the Adrenal Cortex. The method I've explained is how the brain regulates blood pressure. What Christaan posted is how blood pressure is locally mediated. -- Edit: Maybe balance is the wrong word - but rather Fluid Volume regulation. --Edit2: ADH inhibitors exist to modulate bp. $\endgroup$ – MG_MD Feb 10 '16 at 16:03

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