Which physiological changes occur due to sympathetic nervous system activation?

The activation of the sympathetic nervous system is often referred to as the "fight or flight" response, which prepares the body to respond to perceived threats or stressors. When this system is engaged, various physiological changes are initiated to enhance the body's ability to cope with stress.

One of the hallmark changes is the increase in heart rate and blood pressure. This is primarily achieved through the release of catecholamines, such as adrenaline (epinephrine) and norepinephrine, from the adrenal medulla. These hormones stimulate the heart to pump more vigorously and increase the force of each contraction, resulting in a higher heart rate. At the same time, blood vessels constrict in certain areas while dilating in others, optimizing blood flow to essential organs and muscles, thus raising blood pressure.

These changes collectively enhance blood flow and oxygen delivery to tissues, particularly the muscles and the brain, improving physical performance and cognitive function during critical situations. Understanding this physiological response helps in recognizing how the body prepares itself for immediate action, which is crucial in contexts like labor and delivery, where fetal monitoring can provide insight into the well-being of both the mother and the fetus in response to stressors.