Question

The fight-or-flight response is most clearly associated with the release of ________ into the bloodstream.

Answer 1

Adrenaline.
The answer is adrenaline.

Answer 2

Answer: The fight-or-flight response is most clearly associated with the release of epinephrine into the bloodstream.

Any physiological reaction occurring due to something which frightens physically or mentally is fight-or-flight response. In order to produce the fight-or-flight response the hypothalamus activation of the adrenal cortical system and sympathetic nervous system takes place. On receiving the signal from hypothalamus the sympathetic nervous system makes the actions of body speed up or gets tensed and body is in an alert condition.

The impulses are sent by the sympathetic nervous system to the smooth muscles and also glands. As a response to it epinephrine or adrenaline and the norepinephrine or noradrenaline is released by the adrenal medulla in the bloodstream. These stress hormones thus bring about changes in the body such as increase in blood pressure and heart rate.