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91-405: A large gene pool indicates extensive genetic diversity , which is associated with robust populations that can survive bouts of intense selection . Meanwhile, low genetic diversity (see inbreeding and population bottlenecks ) can cause reduced biological fitness and an increased chance of extinction , although as explained by genetic drift new genetic variants, that may cause an increase in

182-446: A major physical trauma or prolonged starvation can greatly disrupt homeostasis. On the other hand, an organism's attempt at restoring conditions back to or near homeostasis, often consuming energy and natural resources, can also be interpreted as stress. The brain cannot sustain an equilibrium under chronic stress; the accumulation of such an ever-deepening deficit is called chronic stress. The ambiguity in defining this phenomenon

273-478: A brief biological background of neuroanatomy and neurochemistry and how they relate to stress. Stress, either severe, acute stress or chronic low-grade stress may induce abnormalities in three principal regulatory systems in the body: serotonin systems , catecholamine systems , and the hypothalamic-pituitary-adrenocortical axis . Aggressive behavior has also been associated with abnormalities in these systems. The brain endocrine interactions are relevant in

364-436: 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

455-443: A decrease in genetic diversity (if a disadvantageous allele is selected against). Hence, genetic diversity plays an important role in the survival and adaptability of a species. The capability of the population to adapt to the changing environment will depend on the presence of the necessary genetic diversity. The more genetic diversity a population has, the more likelihood the population will be able to adapt and survive. Conversely,

546-496: A disease-causing bacterium changes to attack a specific genetic variation, it can easily wipe out vast quantities of the species. If the genetic variation that the bacterium is best at attacking happens to be that which humans have selectively bred to use for harvest, the entire crop will be wiped out. The nineteenth-century Great Famine in Ireland was caused in part by a lack of biodiversity. Since new potato plants do not come as

637-425: A group of mental and behavioral disorders which have their aetiology in reaction to severe stress and the consequent adaptive response. Chronic stress, and a lack of coping resources available, or used by an individual, can often lead to the development of psychological issues such as delusions , depression and anxiety (see below for further information). Chronic stress also causes brain atrophy , which

728-440: 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

819-491: A new egg is produced every time a female mates. By mating with multiple males, the mother increases the genetic diversity within a single litter of cubs. Attempts to increase the viability of a species by increasing genetic diversity is called genetic rescue. For example, eight panthers from Texas were introduced to the Florida panther population, which was declining and suffering from inbreeding depression. Genetic variation

910-416: A number of physical changes that have both short- and long-term effects on the body. The Holmes and Rahe stress scale was developed as a method of assessing the risk of disease from life changes. The scale lists both positive and negative changes that elicit stress. These include things such as a major holiday or marriage, or death of a spouse and firing from a job. Homeostasis is a concept central to

1001-418: A particular locus. This may occur, for instance, if a species has a large range relative to the mobility of individuals within it. Frequency-dependent selection is the hypothesis that as alleles become more common, they become more vulnerable. This occurs in host–pathogen interactions , where a high frequency of a defensive allele among the host means that it is more likely that a pathogen will spread if it

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1092-684: A person with Alzheimer's disease. 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

1183-467: 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

1274-494: 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 . Selye published in year 1975

1365-402: 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

1456-495: 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 . Chronic stress is a term sometimes used to differentiate it from acute stress. Definitions differ, and may be along

1547-517: A range of different objectives. It provides the raw material for selective breeding programmes and allows livestock populations to adapt as environmental conditions change. Livestock biodiversity can be lost as a result of breed extinctions and other forms of genetic erosion . As of June 2014, among the 8,774 breeds recorded in the Domestic Animal Diversity Information System ( DAD-IS ), operated by

1638-402: A rapid decline in genetic diversity may be highly susceptible to extinction. Variation in the populations gene pool allows natural selection to act upon traits that allow the population to adapt to changing environments. Selection for or against a trait can occur with changing environment – resulting in an increase in genetic diversity (if a new mutation is selected for and maintained) or

1729-426: A rapid decrease in genetic diversity. Even with an increase in population size, the genetic diversity often continues to be low if the entire species began with a small population, since beneficial mutations (see below) are rare, and the gene pool is limited by the small starting population. This is an important consideration in the area of conservation genetics , when working toward a rescued population or species that

1820-440: A result of reproduction, but rather from pieces of the parent plant, no genetic diversity is developed, and the entire crop is essentially a clone of one potato, it is especially susceptible to an epidemic. In the 1840s, much of Ireland's population depended on potatoes for food. They planted namely the "lumper" variety of potato, which was susceptible to a rot-causing oomycete called Phytophthora infestans . The fungus destroyed

1911-400: 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

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2002-401: 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

2093-441: 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

2184-474: A spouse with dementia, or may result from brief focal events that have long term effects, such as experiencing a sexual assault. Studies have also shown that psychological stress may directly contribute to the disproportionately high rates of coronary heart disease morbidity and mortality and its etiologic risk factors . Specifically, acute and chronic stress have been shown to raise serum lipids and are associated with clinical coronary events. However, it

2275-451: 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. The third stage could be either exhaustion or recovery : The result can manifest itself in obvious illnesses, such as general trouble with

2366-401: 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. Lazarus argued that, in order for

2457-490: Is able to overcome that allele . A study conducted by the National Science Foundation in 2007 found that genetic diversity (within-species diversity) and biodiversity are dependent upon each other — i.e. that diversity within a species is necessary to maintain diversity among species, and vice versa. According to the lead researcher in the study, Dr. Richard Lankau, "If any one type is removed from

2548-424: Is absent from both lay and expert life narratives before the 1930s". Physiological stress represents a wide range of physical responses that occur as a direct effect of a stressor causing an upset in the homeostasis of the body. Upon immediate disruption of either psychological or physical equilibrium the body responds by stimulating the nervous , endocrine , and immune systems . The reaction of these systems causes

2639-400: Is characterized by three phases: a nonspecific alarm 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. Alarm is the first stage, which is divided into two phases:

2730-536: 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. 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

2821-465: 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

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2912-413: Is genetically healthy. Random mutations consistently generate genetic variation . A mutation will increase genetic diversity in the short term, as a new gene is introduced to the gene pool. However, the persistence of this gene is dependent of drift and selection (see above). Most new mutations either have a neutral or negative effect on fitness, while some have a positive effect. A beneficial mutation

3003-650: 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. 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. A link has been suggested between chronic stress and cardiovascular disease. Stress appears to play

3094-417: Is more likely to occur, thus perpetuating more common alleles to the point of fixation, thus decreasing genetic diversity. Concerns about genetic diversity are therefore especially important with large mammals due to their small population size and high levels of human-caused population effects. A genetic bottleneck can occur when a population goes through a period of low number of individuals, resulting in

3185-408: Is more likely to persist and thus have a long-term positive effect on genetic diversity. Mutation rates differ across the genome, and larger populations have greater mutation rates. In smaller populations a mutation is less likely to persist because it is more likely to be eliminated by drift. Gene flow , often by migration, is the movement of genetic material (for example by pollen in the wind, or

3276-564: Is most often measured indirectly. For example, heritability can be measured as h 2 = V A / V P {\displaystyle h^{2}=V_{A}/V_{P}} or adaptive population differentiation can be measured as Q S T = V G / ( V G + 2 V A ) {\displaystyle Q_{ST}=V_{G}/(V_{G}+2V_{A})} . It may be possible to identify adaptive genes through genome-wide association studies by analyzing genomic data at

3367-470: Is particularly pertinent to mental illnesses, whereby chronic or severe stress remains a common risk factor for several mental illnesses . Acute stressful situations where the stress experienced is severe is a cause of change psychologically to the detriment of the well-being of the individual, such that symptomatic derealization and depersonalization , and anxiety and hyperarousal , are experienced. The International Classification of Diseases includes

3458-536: Is possible for individuals to exhibit hardiness —a term referring to the ability to be both chronically stressed and healthy. Even though psychological stress is often connected with illness or disease, most healthy individuals can still remain disease-free after being confronted with chronic stressful events. This suggests that there are individual differences in vulnerability to the potential pathogenic effects of stress; individual differences in vulnerability arise due to both genetic and psychological factors. In addition,

3549-418: Is the loss of neurons and the connections between them. It affects the part of the brain that is important for learning, responding to the stressors and cognitive flexibility. Chronic stressors may not be as intense as acute stressors such as natural disaster or a major accident, but persist over longer periods of time and tend to have a more negative effect on health because they are sustained and thus require

3640-413: 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

3731-413: The fitness of organisms, are more likely to fix in the population if it is rather small. When all individuals in a population are identical with regard to a particular phenotypic trait, the population is said to be 'monomorphic'. When the individuals show several variants of a particular trait they are said to be polymorphic . The Russian geneticist Alexander Sergeevich Serebrovsky first formulated

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3822-652: The parasympathetic nervous system returns the body to homeostasis . The second major physiological stress-response center, the HPA axis, regulates the release of cortisol , which influences many bodily functions such as metabolic, psychological and immunological functions . The SAM and HPA axes are regulated by several brain regions, including the limbic system , prefrontal cortex , amygdala , hypothalamus , and stria terminalis . Through these mechanisms, stress can alter memory functions , reward , immune function , metabolism and susceptibility to diseases. Disease risk

3913-407: The shock phase and the antishock phase. 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

4004-613: The Food and Agriculture Organization of the United Nations ( FAO ), 17 percent were classified as being at risk of extinction and 7 percent already extinct. There is now a Global Plan of Action for Animal Genetic Resources that was developed under the auspices of the Commission on Genetic Resources for Food and Agriculture in 2007, that provides a framework and guidelines for the management of animal genetic resources. Awareness of

4095-607: The age at which the stress is experienced can dictate its effect on health. Research suggests chronic stress at a young age can have lifelong effects on the biological, psychological, and behavioral responses to stress later in life. The term "stress" had none of its contemporary connotations before the 1920s. It is a form of the Middle English destresse , derived via Old French from the Latin stringere , "to draw tight". The word had long been in use in physics to refer to

4186-728: The body's physiological response to occur daily. This depletes the body's energy more quickly and usually occurs over long periods of time, especially when these microstressors cannot be avoided (i.e. stress of living in a dangerous neighborhood). See allostatic load for further discussion of the biological process by which chronic stress may affect the body. For example, studies have found that caregivers, particularly those of dementia patients, have higher levels of depression and slightly worse physical health than non-caregivers. When humans are under chronic stress, permanent changes in their physiological, emotional, and behavioral responses may occur. Chronic stress can include events such as caring for

4277-476: The body's response to a stressor or embody the act of stress itself is part of the ambiguity in defining what exactly stress is. The central nervous system works closely with the body's endocrine system to regulate these mechanisms. The sympathetic nervous system becomes primarily active during a stress response , regulating many of the body's physiological functions in ways that ought to make an organism more adaptive to its environment. Below there follows

4368-498: The body. In humans and most mammals, the autonomic nervous system and hypothalamic-pituitary-adrenal (HPA) axis are the two major systems that respond to stress. Two well-known hormones that humans produce during stressful situations are adrenaline and cortisol . The sympathoadrenal medullary (SAM) axis may activate the fight-or-flight response through the sympathetic nervous system , which dedicates energy to more relevant bodily systems to acute adaptation to stress, while

4459-408: The brain stem nuclei, particularly the noradrenergic nuclei stimulate CRH release. Other regions of the hypothalamus both directly and indirectly inhibit HPA axis activity. Hypothalamic neurons involved in regulating energy balance also influence HPA axis activity through the release of neurotransmitters such as neuropeptide Y , which stimulates HPA axis activity. Generally, the amygdala stimulates, and

4550-464: The broader context of cognitive-consistency theory . Stress can have many profound effects on the human biological systems. Biology primarily attempts to explain major concepts of stress using a stimulus-response paradigm, broadly comparable to how a psychobiological sensory system operates. The central nervous system (brain and spinal cord) plays a crucial role in the body's stress-related mechanisms. Whether one should interpret these mechanisms as

4641-592: The concept in the 1920s as genofond (gene fund), a word that was imported to the United States from the Soviet Union by Theodosius Dobzhansky , who translated it into English as "gene pool." Harlan and de Wet (1971) proposed classifying each crop and its related species by gene pools rather than by formal taxonomy. Gene pool centres refers to areas on the earth where important crop plants and domestic animals originated. They have an extraordinary range of

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4732-428: The coronavirus RNA genome is catalyzed by an RNA-dependent RNA polymerase . During replication this polymerase may undergo template switching, a form of homologous recombination. This process which also generates genetic diversity appears to be an adaptation for coping with RNA genome damage. The natural world has several ways of preserving or increasing genetic diversity. Among oceanic plankton , viruses aid in

4823-405: The crop. One way farmers get around this is through inter-cropping . By planting rows of unrelated, or genetically distinct crops as barriers between herbivores and their preferred host plant, the farmer effectively reduces the ability of the herbivore to spread throughout the entire plot. The genetic diversity of livestock species permits animal husbandry in a range of environments and with

4914-450: 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

5005-425: The digestive system, secretion of the epinephrine and cortisol from the adrenal medulla, and relaxation of the bladder wall. The parasympathetic nervous response, "rest and digest", involves return to maintaining homeostasis, and involves miosis , bronchoconstriction , increased activity of the digestive system, and contraction of the bladder walls. Complex relationships between protective and vulnerability factors on

5096-474: The effect of childhood home stress on psychological illness, cardiovascular illness and adaption have been observed. ANS related mechanisms are thought to contribute to increased risk of cardiovascular disease after major stressful events. The HPA axis is a neuroendocrine system that mediates a stress response. Neurons in the hypothalamus, particularly the paraventricular nucleus , release vasopressin and corticotropin releasing hormone , which travel through

5187-828: 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. 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

5278-620: The environment, leading to adaptation of the remaining species. Changes in genetic diversity, such as in loss of species, leads to a loss of biological diversity . Loss of genetic diversity in domestic animal populations has also been studied and attributed to the extension of markets and economic globalization . Neutral genetic diversity consists of genes that do not increase fitness and are not responsible for adaptability. Natural selection does not act on these neutral genes. Adaptive genetic diversity consists of genes that increase fitness and are responsible for adaptability to changes in

5369-400: The environment. Adaptive genes are responsible for ecological, morphological, and behavioral traits. Natural selection acts on adaptive genes which allows the organisms to evolve. The rate of evolution on adaptive genes is greater than on neutral genes due to the influence of selection. However, it has been difficult to identify alleles for adaptive genes and thus adaptive genetic diversity

5460-470: The future of a population given measures such as allele frequency and population size. Genetic diversity can also be measured. The various recorded ways of measuring genetic diversity include: Stress (biology) Stress , whether physiological , biological or psychological , is an organism's response to a stressor such as an environmental condition. When stressed by stimuli that alter an organism's environment, multiple systems respond across

5551-512: The future. Large populations are more likely to maintain genetic material and thus generally have higher genetic diversity. Small populations are more likely to experience the loss of diversity over time by random chance, which is an example of genetic drift . When an allele (variant of a gene) drifts to fixation, the other allele at the same locus is lost, resulting in a loss in genetic diversity. In small population sizes, inbreeding , or mating between individuals with similar genetic makeup,

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5642-758: The genetic shifting process. Ocean viruses, which infect the plankton, carry genes of other organisms in addition to their own. When a virus containing the genes of one cell infects another, the genetic makeup of the latter changes. This constant shift of genetic makeup helps to maintain a healthy population of plankton despite complex and unpredictable environmental changes. Cheetahs are a threatened species . Low genetic diversity and resulting poor sperm quality has made breeding and survivorship difficult for cheetahs. Moreover, only about 5% of cheetahs survive to adulthood. However, it has been recently discovered that female cheetahs can mate with more than one male per litter of cubs. They undergo induced ovulation, which means that

5733-425: The genus Arabidopsis , appear to have high adaptive potential despite suffering from low genetic diversity overall due to severe bottlenecks . Therefore species with low neutral genetic diversity may possess high adaptive genetic diversity, but since it is difficult to identify adaptive genes, a measurement of overall genetic diversity is important for planning conservation efforts and a species that has experienced

5824-407: 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

5915-469: The hypophysial portal vessel where they travel to and bind to the corticotropin-releasing hormone receptor on the anterior pituitary gland . Multiple CRH peptides have been identified, and receptors have been identified on multiple areas of the brain, including the amygdala. CRH is the main regulatory molecule of the release of ACTH. The secretion of ACTH into systemic circulation allows it to bind to and activate Melanocortin receptor , where it stimulates

6006-567: The idea of stress. In biology , most biochemical processes strive to maintain equilibrium (homeostasis), a steady state that exists more as an ideal and less as an achievable condition. Environmental factors, internal or external stimuli, continually disrupt homeostasis; an organism's present condition is a state of constant flux moving about a homeostatic point that is that organism's optimal condition for living. Factors causing an organism's condition to diverge too far from homeostasis can be experienced as stress. A life-threatening situation such as

6097-616: The importance of maintaining animal genetic resources has increased over time. FAO has published two reports on the state of the world's animal genetic resources for food and agriculture , which cover detailed analyses of our global livestock diversity and ability to manage and conserve them. High genetic diversity in viruses must be considered when designing vaccinations. High genetic diversity results in difficulty in designing targeted vaccines, and allows for viruses to quickly evolve to resist vaccination lethality. For example, malaria vaccinations are impacted by high levels of genetic diversity in

6188-562: The internal distribution of a force exerted on a material body, resulting in strain . In the 1920s and '30s, biological and psychological circles occasionally used "stress" to refer to a physiological or environmental perturbation that could cause physiological and mental "strain". The amount of strain in reaction to stress depends on the resilience . Excessive strain would appear as illness. Walter Cannon used it in 1926 to refer to external factors that disrupted what he called homeostasis . But "...stress as an explanation of lived experience

6279-460: 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

6370-427: 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,

6461-499: The migration of a bird). Gene flow can introduce novel alleles to a population. These alleles can be integrated into the population, thus increasing genetic diversity. For example, an insecticide -resistant mutation arose in Anopheles gambiae African mosquitoes. Migration of some A. gambiae mosquitoes to a population of Anopheles coluzziin mosquitoes resulted in a transfer of the beneficial resistance gene from one species to

6552-715: The natural regulatory capacity of an organism". The brain cannot live in an harsh family environment, it needs some sort of stability between another brain. People who have reported being raised in harsh environments such as verbal and physical aggression have showed a more immune dysfunction and more metabolic dysfunction. Indeed, in 1995 Toates already defined stress as a "chronic state that arises only when defense mechanisms are either being chronically stretched or are actually failing," while according to Ursin (1988) stress results from an inconsistency between expected events ("set value") and perceived events ("actual value") that cannot be resolved satisfactorily, which also puts stress into

6643-492: The other. The genetic diversity was increased in A. gambiae by mutation and in A. coluzziin by gene flow. When humans initially started farming, they used selective breeding to pass on desirable traits of the crops while omitting the undesirable ones. Selective breeding leads to monocultures : entire farms of nearly genetically identical plants. Little to no genetic diversity makes crops extremely susceptible to widespread disease; bacteria morph and change constantly and when

6734-418: The person with it (Arnold. E and Boggs. K. 2007). Some common categories and examples of stressors include: 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

6825-485: The population level. Identifying adaptive genetic diversity is important for conservation because the adaptive potential of a species may dictate whether it survives or becomes extinct , especially as the climate changes . This is magnified by a lack of understanding whether low neutral genetic diversity is correlated with high genetic drift and high mutation load . In a review of current research, Teixeira and Huber (2021), discovered some species, such as those in

6916-601: The postganglionic nerves, which is controlled by preganglionic neurons originating in the intermediolateral cell column . The ANS receives inputs from the medulla , hypothalamus , limbic system , prefrontal cortex , midbrain and monoamine nuclei . The activity of the sympathetic nervous system drives what is called the "fight or flight" response. The fight or flight response to emergency or stress involves mydriasis , increased heart rate and force contraction, vasoconstriction , bronchodilation , glycogenolysis , gluconeogenesis , lipolysis , sweating , decreased motility of

7007-496: The 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

7098-439: 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, they will, in general, try different strategies. Both negative and positive stressors can lead to stress. The intensity and duration of stress changes depending on the circumstances and emotional condition of

7189-449: The protein antigens. In addition, HIV-1 genetic diversity limits the use of currently available viral load and resistance tests. Coronavirus populations have considerable evolutionary diversity due to mutation and homologous recombination . For example, the sequencing of 86 SARS-CoV-2 coronavirus samples obtained from infected patients revealed 93 mutations indicating the presence of considerable genetic diversity. Replication of

7280-460: The release of steroid hormones . Steroid hormones bind to glucocorticoid receptors in the brain, providing negative feedback by reducing ACTH release. Some evidence supports a second long term feedback that is non-sensitive to cortisol secretion. The PVN of the hypothalamus receives inputs from the nucleus of the solitary tract , and lamina terminalis . Through these inputs, it receives and can respond to changes in blood. The PVN innervation from

7371-537: The span of survival for a species. It is distinguished from genetic variability , which describes the tendency of genetic characteristics to vary. Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Those individuals are more likely to survive to produce offspring bearing that allele. The population will continue for more generations because of

7462-416: The success of these individuals. The academic field of population genetics includes several hypotheses and theories regarding genetic diversity. The neutral theory of evolution proposes that diversity is the result of the accumulation of neutral substitutions. Diversifying selection is the hypothesis that two subpopulations of a species live in different environments that select for different alleles at

7553-456: The system, the cycle can break down, and the community becomes dominated by a single species." Genotypic and phenotypic diversity have been found in all species at the protein , DNA , and organismal levels; in nature, this diversity is nonrandom, heavily structured, and correlated with environmental variation and stress . The interdependence between genetic and species diversity is delicate. Changes in species diversity lead to changes in

7644-410: 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

7735-532: The translation of stress into physiological and psychological changes. The autonomic nervous system (ANS), as mentioned above, plays an important role in translating stress into a response. The ANS responds reflexively to both physical stressors (for example baroreception ), and to higher level inputs from the brain. The ANS is composed of the parasympathetic nervous system and sympathetic nervous system , two branches that are both tonically active with opposing activities. The ANS directly innervates tissue through

7826-399: The vast majority of the potato crop, and left one million people to starve to death. Genetic diversity in agriculture does not only relate to disease, but also herbivores . Similarly, to the above example, monoculture agriculture selects for traits that are uniform throughout the plot. If this genotype is susceptible to certain herbivores, this could result in the loss of a large portion of

7917-448: The vulnerability of a population to changes, such as climate change or novel diseases will increase with reduction in genetic diversity. For example, the inability of koalas to adapt to fight Chlamydia and the koala retrovirus (KoRV) has been linked to the koala's low genetic diversity. This low genetic diversity also has geneticists concerned for the koalas' ability to adapt to climate change and human-induced environmental changes in

8008-451: The vulnerability to stressors is particularly high. This can lead to psychiatric and physical diseases which have long term impacts on an individual. 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

8099-399: The wild counterparts of cultivated plant species and useful tropical plants. Gene pool centres also contain different sub tropical and temperate region species. Genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species , and can be correlated to

8190-576: Was first recognized by Hans Selye (1907–1982) in 1926. In 1951 a commentator loosely summarized Selye's view of stress as something that "...in addition to being itself, was also the cause of itself, and the result of itself". First to use the term in a biological context, Selye continued to define stress as "the non-specific response of the body to any demand placed upon it". Neuroscientists such as Bruce McEwen and Jaap Koolhaas believe that stress, based on years of empirical research, "should be restricted to conditions where an environmental demand exceeds

8281-473: Was thus increased and resulted in a significant increase in population growth of the Florida Panther. Creating or maintaining high genetic diversity is an important consideration in species rescue efforts, in order to ensure the longevity of a population. Genetic diversity of a population can be assessed by some simple measures. Furthermore, stochastic simulation software is commonly used to predict

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