Which of the following is NOT a part of the sympathetic nervous system's response?

The sympathetic nervous system is responsible for the body's "fight or flight" response, which prepares the body to react to stressful situations. During this response, various physiological changes occur to enhance the body's ability to respond quickly to perceived threats.

Adrenaline and nonadrenaline (also known as norepinephrine) are two key hormones released during sympathetic activation. Adrenaline secretion from the adrenal glands leads to increased heart rate, elevated blood pressure, and expanded air passages in the lungs, while nonadrenaline plays a significant role in increasing arousal and readiness. Both of these responses prepare the body for a quick reaction.

Increased heart rate is another characteristic response of the sympathetic nervous system. This is achieved through the direct action of adrenaline and nonadrenaline, which stimulate the heart to pump faster and more forcefully, ensuring that more oxygen and nutrients are delivered to muscles and vital organs.

On the other hand, increased immune response is not typically a function associated with the sympathetic nervous system. In fact, during periods of acute stress, there may be a temporary suppression of certain immune functions as the body prioritizes immediate survival over long-term health. This means that while there may be some immune activation in response to stress, the sympathetic nervous system