What substance regulates fight or flight response?

The fight or flight response is primarily regulated by the hormone adrenaline (also known as epinephrine), which is released by the adrenal glands in response to stress. This hormone prepares the body to react quickly to perceived threats by increasing heart rate, dilating airways, and redirecting blood flow to essential muscles. Additionally, cortisol, another hormone released during stress, helps sustain the body's response over a longer period. Together, these substances coordinate the physiological changes necessary for survival in dangerous situations.