This is a simple guide to adrenaline and its effects on the human body. An adrenaline rush is often referred to as the flight or fight response. You, the writer, put your characters into the most incredible situations and then decide if they will confront the enemy or run away – or do something completely unexpected. But what really happens when a person confronts an assailant or has a panic attack?

Adrenaline is a hormone that is sometimes referred to as epinephrine, but only in American medical circles – and that word may be slowly dying out. Adrenaline is the word of choice in all popular media and around the world.

Your characters are likely to have more than one adrenaline rush on their way to the exciting climax in your story. It happens in response to trauma, shock or a sudden fright. The hormone bursts out of…