User:Jovanna.lanbaxter/Stress (biology)

Effects of chronic stress[edit]
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". Stress on occasions can sometimes have health benefits with regards to maintaining an allostasis.[1] Chronic stress can essentially lead to mental and physical illnesses since the individual’s allostasis is budgeting an undersupplied balance. 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. 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. ''There are different types of stressor that can cause chronic stress. For instance, physical and mental abuse, neglect, verbal and physical aggression are examples of different factors that can cause chronic stress in someone’s day to day life''. 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. Also, your body can’t tell the difference between physical stress or emotional stress and it ends up weakening your immune system due to the excessive stress on the body and mind.

Immunological[edit]
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.

Infectious[edit]
''Studies have discovered that there is a correlation between chronic stress and physical disease, especially in adolescents. For example, verbal abuse has been known to alter the immune response of teenagers enough to reactivate latent viruses (such as the herpes simplex virus, or HSV), reduce the effect of some vaccines, and can even slow the general healing response of the body.''

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.

Chronic disease[edit]
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[edit]
''Long periods of chronic stress can harm the human brain. Studies show that chronic stress, including physical and sexual abuse, aswell as verball aggression can eat away at the brain and body over a long period of time.''

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.

More generally, prenatal life, infancy, childhood, and adolescence are critical periods in which the vulnerability to stressors is particularly high.

Psychopathology[edit]
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, and functional somatic syndromes.

''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 diabetes, 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.''

Innovation

''Chronic stress has a negative impact on one’s ability to create and to innovate. When one devotes themselves to such creative activities, a surplus of energy must be utilized. However, 20% of the body’s metabolic budget is already expended on baseline brain activity. Thus, when an individual is dealing with chronic stress they do not possess the required energy to carry out these creative endeavors.''