phases: the shock phase and the antishock phase. shock phase: during this phase, the body can endure changes such as hypovolemia, hypoosmolarity, hyponatremia, hypochloremia, hypoglycemia—the stressor effect. this phase resembles addison's disease. the organism's resistance to the stressor drops temporarily below the normal range and some level of shock (e.g. circulatory shock) may be experienced. antishock phase: when the threat or stressor is identified or realized, the body starts to respond and is in a state of alarm. during this stage, the locus coeruleus and sympathetic nervous system activate the production of catecholamines including adrenaline, engaging the popularly-known fight-or-flight response. adrenaline temporarily provides increased muscular tonus, increased blood pressure due to peripheral vasoconstriction and tachycardia, and increased glucose in blood. there is also some activation of the hpa axis, producing glucocorticoids (cortisol, aka the s-hormone or stress-hormone). stage 2 resistance is the second stage. during this stage, increased secretion of glucocorticoids intensifies the body's systemic response. glucocorticoids can increase the concentration of glucose, fat, and amino acid in blood. in high doses, one glucocorticoid, cortisol, begins to act similarly to a mineralocorticoid (aldosterone) and brings the body to a state similar to hyperaldosteronism. if the stressor persists, it becomes necessary to attempt some means of coping with the stress. the body attempts to respond to stressful stimuli, but after prolonged activation, the body's chemical resources will be gradually depleted, leading to the final stage. stage 3 the third stage could be either exhaustion or recovery: recovery stage follows when the system's compensation mechanisms have successfully overcome the stressor effect (or have completely eliminated the factor which caused the stress). the high glucose, fat and amino acid levels in blood prove useful for anabolic reactions, restoration of homeostasis and regeneration of cells. exhaustion is the alternative third stage in the gas model. at this point, all of the body's resources are eventually depleted and the body is unable to maintain normal function. the initial autonomic nervous system symptoms may reappear (panic attacks, muscle aches, sore eyes, difficulty breathing, fatigue, heartburn, high blood pressure, and difficult time sleeping, etc.). if stage three is extended, long-term damage may result (prolonged vasoconstriction results in ischemia which in turn leads to cell necrosis), as the body's immune system becomes exhausted, and bodily functions become impaired, resulting in decompensation. the result can manifest itself in obvious illnesses, such as general trouble with the digestive system (e.g. occult bleeding, melena, constipation/obstipation), diabetes, or even cardiovascular problems (angina pectoris), along with clinical depression and other mental illnesses. stress relief a person can stop stress from being overwhelming by exercising when symptoms of stress become apparent, reflecting on their day (thinking about what they accomplished, not what they have not), and speaking to a therapist about their concerns. the parasympathetic nervous system is responsible for calming down the body's arousal and helping a person relax. history in research the current usage of the word stress arose out of hans selye's 1930s experiments. he started to use the term to refer not just to the agent but to the state of the organism as it responded and adapted to the environment. his theories of a universal non-specific stress response attracted great interest and contention in academic physiology and he undertook extensive research programs and publication efforts. while the work attracted continued support from advocates of psychosomatic medicine, many in experimental physiology concluded that his concepts were too vague and unmeasurable. during the 1950s, selye turned away from the laboratory to promote his concept through popular books and lecture tours. he wrote for both non-academic physicians and, in an international bestseller entitled stress of life, for the general public. a broad biopsychosocial concept of stress and adaptation offered the promise of helping everyone achieve health and happiness by successfully responding to changing global challenges and the problems of modern civilization. selye coined the term "eustress" for positive stress, by contrast to distress. he argued that all people have a natural urge and need to work for their own benefit, a message that found favor with industrialists and governments. he also coined the term stressor to refer to the causative event or stimulus, as opposed to the resulting state of stress. selye was in contact with the tobacco industry from 1958 and they were undeclared allies in litigation and the promotion of the concept of stress, clouding the link between smoking and cancer, and portraying smoking as a "diversion", or in selye's concept a "deviation", from environmental stress. from the late 1960s, academic psychologists started to adopt selye's concept; they sought to quantify "life stress" by scoring "significant life events", and a large amount of research was undertaken to examine links between stress and disease of all kinds. by the late 1970s, stress had become the medical area of greatest concern to the general population, and more basic research was called for to better address the issue. there was also renewed laboratory research into the neuroendocrine, molecular, and immunological bases of stress, conceived as a useful heuristic not necessarily tied to selye's original hypotheses. the us military became a key center of stress research, attempting to understand and reduce combat neurosis and psychiatric casualties. the psychiatric diagnosis post-traumatic stress disorder (ptsd) was coined in the mid-1970s, in part through the efforts of anti-vietnam war activists and the vietnam veterans against the war, and chaim f. shatan. the condition was added to the diagnostic and statistical manual of mental disorders as posttraumatic stress disorder in 1980. ptsd was considered a severe and ongoing emotional reaction to an extreme psychological trauma, and as such often associated with soldiers, police officers, and other emergency personnel. the stressor may involve threat to life (or viewing the actual death of someone else), serious physical injury, or threat to physical or psychological integrity. in some cases, it can also be from profound psychological and emotional trauma, apart from any actual physical harm or threat. often, however, the two are combined. by the 1990s, "stress" had become an integral part of modern scientific understanding in all areas of physiology and human functioning, and one of the great metaphors of western life. focus grew on stress in certain settings, such as workplace stress, and stress management techniques were developed. the term also became a euphemism, a way of referring to problems and eliciting sympathy without being explicitly confessional, just "stressed out". it came to cover a huge range of phenomena from mild irritation to the kind of severe problems that might result in a real breakdown of health. in popular usage, almost any event or situation between these extremes could be described as stressful. during this time society spent less attention to the actual danger and severeness to mental health, this society might not have cared about those consequences of what we say or do. we might not agree that those consequences of being harsh to another individual verbally is to be considered abuse but they nonetheless have costs that we all pay. the american psychological association's 2015 stress in america study found that nationwide stress is on the rise and that the three leading sources of stress were "money", "family responsibility", and "work".