How and why does stress have such an impact on physical health when it is meant to be all in the head?

stress and physical health dates back to Hippocrates time. Stress was confirmed by Walter Cannon is a response of a unified mind-body system. Extreme cold, lack of oxygen, and emotion-arousing inidents all trigger an outpouring of stress hormones epinephrin and norepinephrine from your adrenal glands also stress hormones glucocorticoid (i dont think i spelled it correctly) such as cortisol. When stress is chronic is can momentarily mobilize the immune system that defends of illnesses such as little as a cut or infections. The immune system is essential for that it contains lymphocytes such as B and T lymphocytes. B lymphoc fight off viruses in the bone marrow and release antibodies and T fight off in the thymus and other lymphatic tissues and also cancer cells. The brain regulates the secretion of stress hormones. Thus when understress immune response and activity lessens. Stress if chronic (long exposure of stress) may cause heart problems, some psychophysiosological illness such as hypertension and headaches.