norepinephrine

/ˌnɔrɛpɪˈnɛfrɪn/
noun
  1. A hormone and neurotransmitter that helps the body respond to stress by increasing heart rate, blood pressure, and alertness.
    • When you feel scared, your body releases norepinephrine to prepare for action.
    • Exercise can increase levels of norepinephrine, which improves focus.
    • Doctors sometimes use norepinephrine to treat dangerously low blood pressure.