Who Activates the sympathetic nervous system?

The sympathetic nervous system is activated by the hypothalamus, which is a small brain region located at the base of the brain. The hypothalamus is responsible for maintaining homeostasis, which is the body's internal balance. When the hypothalamus senses a threat or stressor, it activates the sympathetic nervous system, which in turn triggers the body's fight-or-flight response. This response prepares the body to either confront the threat or flee from it. The sympathetic nervous system activates the adrenal glands, which release hormones such as adrenaline and cortisol. These hormones increase the heart rate, blood pressure, and breathing, and divert blood flow to the muscles. They also inhibit non-essential bodily functions, such as digestion and reproduction.