Baroreflex Constriction Of The Peripheral Circulation During Exercise

Baroreflex Constriction of the Peripheral Circulation During Exercise

Jul 8, 2011 | By Laura Niedziocha

During exercise, a redistribution of blood flow occurs. At rest, about 15 percent of blood is given to the skeletal muscles, but during exercise, this can increase up to 80 percent to 85 percent. The sympathetic nervous system influences your cardiovascular system by eliciting changes in blood vessels, heart rate and blood pressure. However, none of this could be possible without the feedback given from baroreceptors.

Baroreceptors and Exercise

Baroreceptors provide the feedback necessary for blood pressure regulation. Baroreceptors work by establishing a set point to maintain blood pressure. When exercise begins, the baroreceptors increase their set point based on the intensity of your exercise, ensuring that blood flow keeps up with the demand. The location of the barorecptors, inside the arteries around the heart, allows the receptor to give the brain a real-time indication of the pressure inside the cardiovascular system.

Mechanism

The baroreceptor reports to the medulla when blood pressure needs to increase. The medulla then stimulates innervation of the sympathetic nervous system. The baroreceptors also influence the pressor center of the medulla, the portion of the medulla responsible for increasing blood pressure through vasoconstriction. When blood pressure needs to be raised, the pressor area is stimulated and vasoconstriction occurs. Thus, the baroreceptor is able to influence the rate of blood flow and dilation of vessels based on the blood pressure and blood flow needs of the body.

Significance

This feedback mechanism is important for two reasons. First, it keeps the body's hemodynamics able to keep up with the needs of the body during exercise. Secondly, vasoconstriction facilitates the increase in blood flow needed to the working muscles. Without adequate blood flow, working muscle cells cannot obtain enough oxygen to make the energy they need to produce movement and participate in physical activity.

Chronic Adaptations

As fitness increases, so does the activity of the baroreceptors. This adaptation makes the response of your body to exercise more effective and efficient. Immediate changes in blood pressure, vasoconstriction and heart rate at the onset of exercise, as provided by the baroreceptor function prepare your body for the demands of exercise.