prefrontal cortex and hippocampus attenuate, hpa axis activity; however, complex relationships do exist between the regions. the immune system may be heavily influenced by stress. the sympathetic nervous system innervates various immunological structures, such as bone marrow and the spleen, allowing for it to regulate immune function. the adrenergic substances released by the sympathetic nervous system can also bind to and influence various immunological cells, further providing a connection between the systems. the hpa axis ultimately results in the release of cortisol, which generally has immunosuppressive effects. however, the effect of stress on the immune system is disputed, and various models have been proposed in an attempt to account for both the supposedly "immunodeficiency" linked diseases and diseases involving hyper activation of the immune system. one model proposed to account for this suggests a push towards an imbalance of cellular immunity(th1) and humoral immunity(th2). the proposed imbalance involved hyperactivity of the th2 system leading to some forms of immune hypersensitivity, while also increasing risk of some illnesses associated with decreased immune system function, such as infection and cancer. effects of chronic stress main article: chronic stress chronic stress is a term sometimes used to differentiate it from acute stress. definitions differ, and may be along the lines of continual activation of the stress response, stress that causes an allostatic shift in bodily functions, or just as "prolonged stress". for example, results of one study demonstrated that individuals who reported relationship conflict lasting one month or longer have a greater risk of developing illness and show slower wound healing. it can also reduce the benefits of receiving common vaccines. similarly, the effects that acute stressors have on the immune system may be increased when there is perceived stress and/or anxiety due to other events. for example, students who are taking exams show weaker immune responses if they also report stress due to daily hassles. while responses to acute stressors typically do not impose a health burden on young, healthy individuals, chronic stress in older or unhealthy individuals may have long-term effects that are detrimental to health. immunological acute time-limited stressors, or stressors that lasted less than two hours, results in an up regulation of natural immunity and down regulation of specific immunity. this type of stress saw in increase in granulocytes, natural killer cells, iga, interleukin 6, and an increase in cell cytotoxicity. brief naturalistic stressors elicit a shift from th1 (cellular) to th2 (humoral) immunity, while decreased t-cell proliferation, and natural killer cell cytotoxicity. stressful event sequences did not elicit a consistent immune response; however, some observations such as decreased t-cell proliferation and cytotoxicity, increase or decrease in natural killer cell cytotoxicity, and an increase in mitogen pha. chronic stress elicited a shift toward th2 immunity, as well as decreased interleukin 2, t cell proliferation, and antibody response to the influenza vaccine. distant stressors did not consistently elicit a change in immune function. another response to high impacts of chronic stress that lasts for a long period of time, is more immune dysfunction and more metabolic dysfunction. it is proven in studies that when continuously being in stressful situations, it is more likely to get sick. also, when being exposed to stress, some claim that the body metabolizes the food in a certain way that adds extra calories to the meal, regardless of the nutritional values of the food. infectious some studies have observed increased risk of upper respiratory tract infection during chronic life stress. in patients with hiv, increased life stress and cortisol was associated with poorer progression of hiv. also with an increased level of stress, studies have proven evidence that it can reactivate latent herpes viruses. chronic disease a link has been suggested between chronic stress and cardiovascular disease. stress appears to play a role in hypertension, and may further predispose people to other conditions associated with hypertension. stress may precipitate abuse of drugs and/or alcohol. stress may also contribute to aging and chronic diseases in aging, such as depression and metabolic disorders. the immune system also plays a role in stress and the early stages of wound healing. it is responsible for preparing the tissue for repair and promoting recruitment of certain cells to the wound area. consistent with the fact that stress alters the production of cytokines, graham et al. found that chronic stress associated with care giving for a person with alzheimer's disease leads to delayed wound healing. results indicated that biopsy wounds healed 25% more slowly in the chronically stressed group, or those caring for a person with alzheimer's disease. development chronic stress has also been shown to impair developmental growth in children by lowering the pituitary gland's production of growth hormone, as in children associated with a home environment involving serious marital discord, alcoholism, or child abuse. chronic stress also has a lot of illnesses and health care problems other than mental that comes with it. severe chronic stress for long periods of time can lead to an increased chance of catching illnesses such as diabetes, cancer, depression, heart disease and alzheimer's disease. more generally, prenatal life, infancy, childhood, and adolescence are critical periods in which the vulnerability to stressors is particularly high. this can lead to psychiatric and physical diseases which have long term impacts on an individual. psychopathology chronic stress is seen to affect the parts of the brain where memories are processed through and stored. when people feel stressed, stress hormones get over-secreted, which affects the brain. this secretion is made up of glucocorticoids, including cortisol, which are steroid hormones that the adrenal gland releases, although this can increase storage of flashbulb memories it decreases long-term potentiation (ltp). the hippocampus is important in the brain for storing certain kinds of memories and damage to the hippocampus can cause trouble in storing new memories but old memories, memories stored before the damage, are not lost. also high cortisol levels can be tied to the deterioration of the hippocampus and decline of memory that many older adults start to experience with age. these mechanisms and processes may therefore contribute to age-related disease, or originate risk for earlier-onset disorders. for instance, extreme stress (e.g. trauma) is a requisite factor to produce stress-related disorders such as post-traumatic stress disorder. chronic stress also shifts learning, forming a preference for habit based learning, and decreased task flexibility and spatial working memory, probably through alterations of the dopaminergic systems. stress may also increase reward associated with food, leading to weight gain and further changes in eating habits. stress may contribute to various disorders, such as fibromyalgia, chronic fatigue syndrome, depression, as well as other mental illnesses and functional somatic syndromes. psychological concepts main article: stress (psychological) eustress selye published in year 1975 a model dividing stress into eustress and distress. where stress enhances function (physical or mental, such as through strength training or challenging work), it may be considered eustress. persistent stress that is not resolved through coping or adaptation, deemed distress, may lead to anxiety or withdrawal (depression) behavior. the difference between experiences that result in eustress and those that result in distress is determined by the disparity between an experience (real or imagined) and personal expectations, and resources to cope with the stress. alarming experiences, either real or imagined, can trigger a stress response. coping main article: stress management responses to stress include adaptation, psychological coping such as stress management, anxiety, and depression. over the long term, distress can lead to diminished health and/or increased propensity to illness; to avoid this, stress must be managed. stress management encompasses techniques intended to equip a person with effective coping mechanisms for dealing with psychological stress, with stress defined as a person's physiological response to an internal or external stimulus that triggers the fight-or-flight response. stress management is effective when a person uses strategies to cope with or alter stressful situations. there are several ways of coping with stress, such as controlling the source of stress or learning to set limits and to say "no" to some of the demands that bosses or family members may make. a person's capacity to tolerate the source of stress may be increased by thinking about another topic such as a hobby, listening to music, or spending time in a wilderness. a way to control stress is first dealing with what is causing the stress if it is something the individual has control over. other methods to control stress and reduce it can be: to not procrastinate and leave tasks for the last minute, do things you like, exercise, do breathing routines, go out with friends, and take a break. having support from a loved one also helps a lot in reducing stress. one study showed that the power of having support from a loved one, or just having social support, lowered stress in individual subjects. painful shocks were applied to married women's ankles. in some trials women were able to hold their husband's hand, in other trials they held a stranger's hand, and then held no one's hand. when the women were holding their husband's hand, the response was reduced in many brain areas. when holding the stranger's hand the response was reduced a little, but not as much as when they were holding their husband's hand. social support helps reduce stress and even more so if the support is from a loved one. cognitive appraisal lazarus argued that, in order for a psychosocial situation to be stressful, it must be appraised as such. he argued that cognitive processes of appraisal are central in determining whether a situation is potentially threatening, constitutes a harm/loss or a challenge, or is benign. both personal and environmental factors influence this primary appraisal, which then triggers the selection of coping processes. problem-focused coping is directed at managing the problem, whereas emotion-focused coping processes are directed at managing the negative emotions. secondary appraisal refers to the evaluation of the resources available to cope with the problem, and may alter the primary appraisal. in other words, primary appraisal includes the perception of how stressful the problem is and the secondary appraisal of estimating whether one has more than or less than adequate resources to deal with the problem that affects the overall appraisal of stressfulness. further, coping is flexible in that, in general, the individual examines the effectiveness of the coping on the situation; if it is not having the desired effect, s/he will, in general, try different strategies. assessment health risk factors both negative and positive stressors can lead to stress. the intensity and duration of stress changes depending on the circumstances and emotional condition of the person with it (arnold. e and boggs. k. 2007). some common categories and examples of stressors include: sensory input such as pain, bright light, noise, temperatures, or environmental issues such as a lack of control over environmental circumstances, such as food, air and/or water quality, housing, health, freedom, or mobility. social issues can also cause stress, such as struggles with conspecific or difficult individuals and social defeat, or relationship conflict, deception, or break ups, and major events such as birth and deaths, marriage, and divorce. life experiences such as poverty, unemployment, clinical depression, obsessive compulsive disorder, heavy drinking, or insufficient sleep can also cause stress. students and workers may face performance pressure stress from exams and project deadlines. adverse experiences during development (e.g. prenatal exposure to maternal stress, poor attachment histories, sexual abuse) are thought to contribute to deficits in the maturity of an individual's stress response systems. one evaluation of the different stresses in people's lives is the holmes and rahe stress scale. general adaptation syndrome a diagram of the general adaptation syndrome model physiologists define stress as how the body reacts to a stressor - a stimulus, real or imagined. acute stressors affect an organism in the short term; chronic stressors over the longer term. the general adaptation syndrome (gas), developed by hans selye, is a profile of how organisms respond to stress; gas is characterized by three phases: a nonspecific mobilization phase, which promotes sympathetic nervous system activity; a resistance phase, during which the organism makes efforts to cope with the threat; and an exhaustion phase, which occurs if the organism fails to overcome the threat and depletes its physiological resources. stage 1 alarm is the first stage, which is divided into two