Simple Explanation
They also activate an emotional response in the amygdala of the brain, such as fear of the threat. At the same time, they have effects on attention and other cognitive functions, and can lead to increased aversive long-term memories. You are ready to fight or flee and you are more likely to remember the threat to react to it in the future.
Technical Explanation
As the stress response is triggered and the body’s sympathetic nervous system (SNS) is activated, the adrenal glands release stress hormones like cortisol, while the sympathetic-adrenomedullary axis (SAM) is also triggered to release catecholamines. These circulate through the bloodstream and the brain. They act on neuroreceptor sites to create changes in the body to mobilize energy. This is part of “fight or flight,” preparing your body to take action. The immediate effects of catecholamines include:
Constricting the blood vessels in the skinIncreasing glucose in your bloodstreamIncreasing your cardiac outputMaking you feel excitedOpening up your lungsRetaining sodiumSending more blood flow to your skeletal musclesSlowing down the intestines
Your heart is beating faster and directing the flow to your muscles so you’ll be able to run or fight. By reducing flow to your skin, there may be less bleeding in case of an injury. You breathe faster and take in more oxygen. Prolonged exposure to catecholamines can create negative psychological and physical outcomes. Prolonged release of catecholamines can reduce the effects of certain neurotransmitters that affect mood, creating a negative feedback loop between emotions and physiology. These changes can also lead to chronic inflammation of organs and the failure of adaptive systems. This can lead to behavior and quality of life changes, sleep disturbances, metabolic disturbances, and cardiovascular disturbances. A negative feedback loop resolves the stress response, allowing a shift to the body’s parasympathetic nervous system (PNS) or the relaxation response, and returns the body to its prestressed state when the perceived threat is gone.
