fight-or-flight response

1. A physiological reaction in response to stress, characterized by an increase in heart rate and blood pressure, elevation of glucose levels in the blood, and redistribution of blood from the digestive tract to the muscles. These changes are caused by activation of the sympathetic nervous system by epinephrine (adrenaline), which prepares the body to challenge or flee from a perceived threat.

Example Sentences

“The medical effects of this are so profound and people don’t understand it, but it triggers a fight-or-flight response that triggers all kinds of stress hormones,” said Nalini Lasiewicz, who runs a nonprofit called Pickleball Noise Relief that has helped conduct studies on the harmful effects the sounds of pickleball can have on nearby residents.

From Los Angeles Times

This is part of the body's fight-or-flight response that has evolved to help us react quickly to the sounds like a predator crashing through the bushes.

From BBC

One common response to fear is the fight-or-flight response.

From Salon

“We’re talking about a fear response and anxiety accompanying it — it can trigger a fight-or-flight response to avoid it,” Kross says.

From Los Angeles Times

Exposure to stress triggers not only the fight-or-flight response, but in many situations it also initiates what psychologists call the “tend-and-befriend” system.

From Salon