There are 2 systems responsible for the spread of stress in the body: the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis of our endocrine system. Let's figure out what happens “behind the curtain” when something unusual and unexpected happens. A car suddenly appears around the corner... Someone shouted loudly nearby... The boss unexpectedly calls in... A favorite vase is broken... Etc. The first to react is a piece of the brain called the amygdala. This is one of the most ancient structures of the brain. We can say that it acts as a kind of “alarm bell.” The amygdala sends an alarm signal, triggering several reactions: - the thalamus sends a “Wake up” signal to the brain stem (an ancient department responsible for instinctive reactions), it releases the stimulating hormone norepinephrine into the brain. - The SNS sends a signal to the main organs and muscle groups of our body so that they are ready to flee from unexpected danger or fight - the hypothalamus (the main manager of the endocrine system) causes the pituitary gland to “order” the adrenal glands to release “stress hormones” - adrenaline and cortisol. Pituitary gland After a second or two, the brain is on alert: adrenaline makes our heart beat faster (and pump more blood), dilates the pupils (so that they collect more light). Norepinephrine keeps blood flowing to major muscle groups and our lungs are primed for increased gas exchange so we can run faster or hit harder. Cortisol firstly suppresses the immune system to reduce the chance of inflammation in wounds; Second, it causes the brainstem to further excite the amygdala, which in turn further excites the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis, which releases more cortisol. Thirdly, cortisol suppresses the activity of the hippocampus (which usually inhibits the activity of the amygdala), and the amygdala “gets freedom”, which ultimately leads to the release of even larger doses of cortisol into the blood - and the vicious stress circle is closed, the chain begins again.. .The hippocampus is indicated in blue, the amygdala is indicated in blue. Appetite disappears, salivation decreases, peristalsis slows down, the mouth dries out, the stomach stops working. Emotions intensify, organize and stimulate the activity of the entire brain. Activation of the SNS/HPA systems excites the amygdala, and it is ready to focus on negative information and react sharply to it. And the state of stress provokes in us a feeling of fear and anger. In the harsh conditions in which our evolution took place, such activation of many body systems helped us survive. But in modern conditions, this condition takes resources away from long-term projects (for example, maintaining a strong immune system or maintaining a good mood) for the sake of short-term crises..