baroreceptorrefleksen

Baroreceptor reflex, also known as the baroreflex, is a physiological mechanism that helps regulate blood pressure and heart rate. It is a negative feedback loop that monitors the pressure within the blood vessels and adjusts the cardiovascular system accordingly. The baroreceptors are specialized sensory receptors located in the walls of the carotid sinus and aortic arch, which are sensitive to changes in blood pressure.

When blood pressure increases, the baroreceptors stretch, sending signals to the brainstem via the glossopharyngeal and vagus nerves. This information is processed in the nucleus tractus solitarii, which then sends signals to the cardiovascular centers in the medulla oblongata. These centers respond by activating the parasympathetic nervous system, which slows the heart rate, and the sympathetic nervous system, which causes vasodilation (widening of blood vessels) to lower blood pressure.

Conversely, when blood pressure decreases, the baroreceptors are less stretched, leading to a decrease in the firing rate of the afferent nerve fibers. This results in a decrease in parasympathetic activity and an increase in sympathetic activity, which causes vasoconstriction (narrowing of blood vessels) and an increase in heart rate to raise blood pressure.

The baroreceptor reflex is crucial for maintaining homeostasis, as it ensures that the body can respond to changes in blood pressure quickly and effectively. Dysfunction of the baroreceptor reflex can lead to conditions such as orthostatic hypotension, where a person experiences a drop in blood pressure upon standing, and orthostatic hypertension, where blood pressure rises upon standing.