What is the neurotransmitter that is similar to adrenaline and plays a major role in the sympathetic nervous system?

The neurotransmitter similar to adrenaline is norepinephrine (noradrenaline). It plays a crucial role in the sympathetic nervous system by facilitating the "fight or flight" response, which prepares the body to react to stress or danger. Norepinephrine increases heart rate, blood flow to muscles, and energy availability, enhancing alertness and readiness for action.