Barorefleksien

Barorefleksien, also known as the baroreceptor reflex, is a rapid, short-term mechanism the body uses to regulate blood pressure. It is a crucial homeostatic feedback loop that helps maintain stable circulation. The primary components of the baroreflex are specialized stretch receptors called baroreceptors, located in the walls of the carotid arteries in the neck and the aorta, the main artery leaving the heart.

When blood pressure increases, these baroreceptors are stretched, increasing their firing rate. This signal is transmitted to the brainstem, specifically to the cardiovascular centers. In response, the brainstem decreases sympathetic nervous system output and increases parasympathetic nervous system output. This leads to vasodilation (widening of blood vessels) and a decrease in heart rate and contractility, effectively lowering blood pressure back to normal.

Conversely, when blood pressure falls, baroreceptor firing decreases. The brainstem then increases sympathetic activity and reduces parasympathetic activity. This results in vasoconstriction (narrowing of blood vessels), an increase in heart rate, and greater heart contractility, raising blood pressure. The baroreflex is constantly active, making adjustments within seconds to minute-to-minute changes in blood pressure, such as those that occur when standing up or during exercise. While essential for immediate blood pressure control, it is not the primary mechanism for long-term blood pressure regulation.