The sympathetic nervous system is responsible for responding to perceived stress. When activated, the “fight-or-flight” response is initiated. Part of this response includes stimulation of the cardiovascular system leading to increased cardiac output. Heart rate, blood pressure, and skeletal muscle perfusion are all increased. On the other hand, gastrointestinal and excretory organ perfusion are lessened and blood is diverted to organs such as the heart, brain, and lungs. Because of this, digestion slows and sphincters close, preventing bowel movements or urine elimination. Additionally, activation of the RAAS and the stimulation of aldosterone release contribute to increasing blood pressure by retaining water and elevating blood volume. In
