Biological Systems Involved in the Stress Response
According to Goleman (2006), the fight or flight system can cause post-traumatic stress in humans. He defined PTSD in humans as “that condition of vigilance and over-reactivity” (p. 225). Goleman described the biological systems that are involved in preparing humans to face a physical or emotional threat. “In linking stress to health, the key biological systems are the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis” (p. 226). When faced with a threat, either emotional or physical, the SNS and the HPA axis deliver hormones that prepare the body to meet the challenge. The protocol includes taking resources from both the immune and endocrine systems, which can have the effect of diminishing both. According to Goleman, this weakening can continue for a minute or many years. According to Lehrer et al. (2007), “The hypothalamic-pituitary-adrenal (HPA) axis, a three-component biological system comprising the hypothalamus and pituitary regions of the brain and the adrenal glands, evolves into a hypersensitive system” (p. 19). While the activation of the SNS and release of fight-or-flight hormones might provide a solution to a short-lived problem, Bjorntorp, Holm, and Rosmond (1999) asserted that the chronic recruitment of stress hormones is responsible for inflammatory disease, insulin resistance, and endocrine abnormalities. These levels of biological stress, whether lasting a moment or years, create what is scientifically called an “allostatic load” (McEwen, 1998). It is the allostatic load that is the culprit in bringing on disease.
“Under stress, the adrenal glands release cortisol, one of the hormones the body mobilizes in an emergency. These hormones have widespread effects in the body, including many that are adaptive in the short term for healing bodily injuries” (Goleman, 2006, p. 225). Cortisol, if allowed to remain high for too long, can damage both the cardiovascular and immune systems, leading to disorders such as diabetes and hypertension. Also, neurons in the hippocampus are affected by cortisol, leading to a distortion in size and a harmful impact on memory.