What is the neurotransmitter that triggers our fight or flight response?
Answer
The fight or flight response is also called the acute stress response or hyperarousal; it is a physiological reaction that occurs when the brain perceives an imminent threat. Epinephrine (also known as adrenaline) is the neurotransmitter most responsible for this response. It can signal an increase in blood flow to muscles and greater blood flow through the heart, among other things (this is why your heart starts to beat quickly when you are afraid).
The hypothalamus sends a nervous signal down to the adrenal medulla. It gives off epinephrine or adrenaline a chemical signal attached to the circulatory system; it's going to bind to proteins on the surface of those cells. In the liver, it's going to trigger a signal transduction pathway. It's going to convert glycogen to glucose. Now you have a supply of energy. Now glucose is going to be coursing through our body along with epinephrine. Epinephrine goes to other places in the body. What does it do to the cells of the lungs? It's going to speed up that breathing rate. What's it going to do in the heart? Epinephrine will trigger a signal transduction pathway in the heart that is very similar to the one found in liver cells. It does not cause a release of glucose, but increases the rate of the beating of those cardiac cells. What do you think will happen to the digestive system? Epinephrine goes there too but what's it going to do is vasoconstrict to slow down digestion. It's going to slow down those blood vessels that feed those areas that allow us to break down and digest food. Because when you are getting out of the way of a car or fighting an attacker, you don't need to concentrate on breaking down breakfast. At the muscles, the blood vessels will vasodilate.