Stress (physiology)
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Stress, either
physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
, biological or
psychological Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between t ...
, is an organism's response to a
stressor A stressor is a chemical or biological agent, environmental condition, external stimulus or an event seen as causing stress to an organism. Psychologically speaking, a stressor can be events or environments that individuals might consider demandin ...
such as an environmental condition. Stress is the body's method of reacting to a condition such as a threat, challenge or physical and
psychological Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between t ...
barrier. There are two hormones that an individual produces during a stressful situation, these are well known as
adrenaline Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and ...
and cortisol. There are two kinds of stress hormone levels. Resting (basal) cortisol levels are normal everyday quantities that are essential for standard functioning. Reactive cortisol levels are increases in cortisol in response to stressors. Stimuli that alter an organism's environment are responded to by multiple systems in the body. In humans and most mammals, the
autonomic nervous system The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies viscera, internal organs, smooth muscle and glands. The autonomic nervous system is a control ...
and hypothalamic-pituitary-adrenal (HPA) axis are the two major systems that respond to stress. The sympathoadrenal medullary (SAM) axis may activate the
fight-or-flight response The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first des ...
through the
sympathetic nervous system The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of th ...
, which dedicates energy to more relevant bodily systems to
acute Acute may refer to: Science and technology * Acute angle ** Acute triangle ** Acute, a leaf shape in the glossary of leaf morphology * Acute (medicine), a disease that it is of short duration and of recent onset. ** Acute toxicity, the adverse eff ...
adaptation to stress, while the
parasympathetic nervous system The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of ...
returadrenaliney 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 The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.Schacter, Daniel L. 2012. ''Ps ...
,
prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, ...
,
amygdala The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verteb ...
,
hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...
, and
stria terminalis The stria terminalis (or terminal stria) is a structure in the brain consisting of a band of fibers running along the lateral margin of the ventricular surface of the thalamus. Serving as a major output pathway of the amygdala, the stria termina ...
. Through these mechanisms, stress can alter memory functions,
reward Reward may refer to: Places * Reward (Shelltown, Maryland), a historic home in Shelltown Maryland * Reward, California (disambiguation) * Reward-Tilden's Farm, a historic home in Chestertown Maryland Arts, entertainment, and media * "Rewa ...
,
immune function The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
,
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
and susceptibility to diseases. Disease risk is particularly pertinent to mental illnesses, whereby chronic or severe stress remains a common risk factor for several
mental illness A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitti ...
es.


Psychology

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 Derealization is an alteration in the perception of the external world, causing those with the condition to perceive it as unreal, distant, distorted or falsified. Other symptoms include feeling as if one's environment is lacking in spontaneity, ...
and
depersonalization Depersonalization can consist of a detachment within the self, regarding one's mind or body, or being a detached observer of oneself. Subjects feel they have changed and that the world has become vague, dreamlike, less real, lacking in significa ...
, and anxiety and
hyperarousal The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first des ...
, are experienced. The
International Classification of Diseases The International Classification of Diseases (ICD) is a globally used diagnostic tool for epidemiology, health management and clinical purposes. The ICD is maintained by the World Health Organization (WHO), which is the directing and coordinating ...
includes a group of mental and
behavioral Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as well ...
disorders which have their
aetiology Etiology (pronounced ; alternatively: aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek (''aitiología'') "giving a reason for" (, ''aitía'', "cause"); and ('' -logía''). More completely, e ...
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
delusion A delusion is a false fixed belief that is not amenable to change in light of conflicting evidence. As a pathology, it is distinct from a belief based on false or incomplete information, confabulation, dogma, illusion, hallucination, or som ...
s, depression and
anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
(see below for further information). Chronic stress also causes brain atrophy, which 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, tend to have a more negative effect on health because they are sustained and thus require 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 Allostatic load is "the wear and tear on the body" which accumulates as an individual is exposed to repeated or chronic stress. The term was coined by Bruce McEwen and Eliot Stellar in 1993. It represents the physiological consequences of chro ...
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 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 Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of atherosclerotic pla ...
morbidity A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
and mortality and its etiologic
risk factors In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often use ...
. Specifically, acute and chronic stress have been shown to raise
serum lipids Blood lipids (or blood fats) are lipids in the blood, either free or bound to other molecules. They are mostly transported in a protein capsule, and the density of the lipids and type of protein determines the fate of the particle and its influence ...
and are associated with clinical coronary events. However, it 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, 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.


Etymology and historical usage

The term "stress" had none of its contemporary connotations before the 1920s. It is a form of the
Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English p ...
''destresse'', derived via
Old French Old French (, , ; Modern French: ) was the language spoken in most of the northern half of France from approximately the 8th to the 14th centuries. Rather than a unified language, Old French was a linkage of Romance dialects, mutually intelligib ...
from the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''stringere'', "to draw tight". The word had long been in use in
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
to refer to the internal distribution of a force exerted on a material body, resulting in
strain Strain may refer to: Science and technology * Strain (biology), variants of plants, viruses or bacteria; or an inbred animal used for experimental purposes * Strain (chemistry), a chemical stress of a molecule * Strain (injury), an injury to a mu ...
. In the 1920s and '30s, biological and psychological circles occasionally used the term to refer to a mental strain or to a harmful environmental agent that could cause illness.
Walter Cannon Walter Bradford Cannon (October 19, 1871 – October 1, 1945) was an American physiologist, professor and chairman of the Department of Physiology at Harvard Medical School. He coined the term "fight or flight response", and developed the theory ...
used it in 1926 to refer to external factors that disrupted what he called
homeostasis In biology, homeostasis (British English, British also homoeostasis) Help:IPA/English, (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. Thi ...
. But "...stress as an explanation of lived experience 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 immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinters, ...
. The reaction of these systems causes a number of physical changes that have both short- and long-term effects on the body. The
Holmes and Rahe stress scale The Holmes and Rahe stress scale () is a list of 43 stressful life events that can contribute to illness. The test works via a point accumulation score which then gives an assessment of risk. The American Institute of Stress for instance, regards ...
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.


Biological need for equilibrium

Homeostasis In biology, homeostasis (British English, British also homoeostasis) Help:IPA/English, (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. Thi ...
is a concept central to the idea of stress. In
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
, most
biochemical Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology an ...
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 a major physical trauma or prolonged
starvation Starvation is a severe deficiency in caloric energy intake, below the level needed to maintain an organism's life. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, dea ...
can greatly disrupt homeostasis. On the other hand, an organism's attempt at restoring conditions back to or near homeostasis, often consuming
energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
and natural resources, can also be interpreted as stress. The brain cannot sustain a concentrated equilibrium under chronic stress, overtime if you constantly struggle in a simmering sea of stress, and you body budget accrued an ever-deepening deficit, that's called chronic stress and it does more than just make you miserable in that moment, It can and will gradually eat away at your brain and cause illness in your body. The ambiguity in defining this phenomenon was first recognized by
Hans Selye János Hugo Bruno "Hans" Selye (; hu, Selye János; January 26, 1907 – October 16, 1982) was a pioneering Hungarian-Canadian endocrinologist who conducted important scientific work on the hypothetical non-specific response of an organism to s ...
(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 Bruce Sherman McEwen (January 17, 1938 – January 2, 2020) was an American neuroendocrinologist and head of the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology at Rockefeller University. He was known for his work on the eff ...
and Jaap Koolhaas believe that stress, based on years of empirical research, "should be restricted to conditions where an environmental demand exceeds 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 the broader context of cognitive-consistency theory.


Biological background

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 The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...
(brain and spinal cord) plays a crucial role in the body's stress-related mechanisms. Whether one should interpret these mechanisms as the body's response to a
stressor A stressor is a chemical or biological agent, environmental condition, external stimulus or an event seen as causing stress to an organism. Psychologically speaking, a stressor can be events or environments that individuals might consider demandin ...
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 The endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs. In vertebrates, the hypothalamus is the neu ...
to regulate these mechanisms. The
sympathetic nervous system The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of th ...
becomes primarily active during a
stress response The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first des ...
, regulating many of the body's
physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
functions in ways that ought to make an organism more
adaptive Adaptation, in biology, is the process or trait by which organisms or population better match their environment Adaptation may also refer to: Arts * Adaptation (arts), a transfer of a work of art from one medium to another ** Film adaptation, a ...
to its environment. Below there follows a brief biological background of
neuroanatomy Neuroanatomy is the study of the structure and organization of the nervous system. In contrast to animals with radial symmetry, whose nervous system consists of a distributed network of cells, animals with bilateral symmetry have segregated, defin ...
and
neurochemistry Neurochemistry is the study of chemicals, including neurotransmitters and other molecules such as psychopharmaceuticals and neuropeptides, that control and influence the physiology of the nervous system. This particular field within neuroscience ...
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 Aggression is overt or covert, often harmful, social interaction with the intention of inflicting damage or other harm upon another individual; although it can be channeled into creative and practical outlets for some. It may occur either reacti ...
has also been associated with abnormalities in these systems.


Biology of stress

The brain endocrine interactions are relevant in the translation of stress into physiological and psychological changes. The
autonomic nervous system The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies viscera, internal organs, smooth muscle and glands. The autonomic nervous system is a control ...
(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 The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of ...
and
sympathetic nervous system The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of th ...
, two branches that are both tonically active with opposing activities. The ANS directly innervates tissue through the postganglionic nerves, which is controlled by preganglionic neurons originating in the
intermediolateral cell column The intermediolateral nucleus (IML) is a region of grey matter found in one of the three grey columns of the spinal cord, the lateral grey column. This is Rexed lamina VII. The intermediolateral cell column exists at vertebral levels T1 – L ...
. The ANS receives inputs from the
medulla Medulla or Medullary may refer to: Science * Medulla oblongata, a part of the brain stem * Renal medulla, a part of the kidney * Adrenal medulla, a part of the adrenal gland * Medulla of ovary, a stroma in the center of the ovary * Medulla of t ...
,
hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...
,
limbic system The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.Schacter, Daniel L. 2012. ''Ps ...
,
prefrontal cortex In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, ...
,
midbrain The midbrain or mesencephalon is the forward-most portion of the brainstem and is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation. The name comes from the Greek ''mesos'', " ...
and
monoamine nuclei Monoamine nuclei are clusters of cells that primarily use monoamine neurotransmitters to communicate. The raphe nuclei, ventral tegmental area, and locus coeruleus have been included in texts about monoamine nuclei. These nuclei receive a variet ...
. 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 Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessel ...
,
bronchodilation A bronchodilator or broncholytic (although the latter occasionally includes secretory inhibition as well) is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lun ...
, glycogenolysis,
gluconeogenesis Gluconeogenesis (GNG) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. It is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. In vertebrat ...
,
lipolysis Lipolysis is the metabolic pathway through which lipid triglycerides are hydrolyzed into a glycerol and free fatty acids. It is used to mobilize stored energy during fasting or exercise, and usually occurs in fat adipocytes. The most important ...
, sweating, decreased motility of 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 Miosis, or myosis (), is excessive constriction of the pupil.Farlex medical dictionary
citing: ...
,
bronchoconstriction Bronchoconstriction is the constriction of the airways in the lungs due to the tightening of surrounding smooth muscle, with consequent coughing, wheezing, and shortness of breath. Causes The condition has a number of causes, the most common be ...
, increased activity of the digestive system, and contraction of the bladder walls. Complex relationships between protective and vulnerability factors on 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 HPA may refer to: Organizations * Harry Potter Alliance, a charity * Halifax Port Authority, Canada * Hamburg Port Authority, Germany * Hawaii Preparatory Academy, a school in Hawaii, US * Health Protection Agency, UK * Heerespersonalamt, the Ger ...
is a neuroendocrine system that mediates a stress response. Neurons in the hypothalamus, particularly the
paraventricular nucleus The paraventricular nucleus (PVN, PVA, or PVH) is a nucleus in the hypothalamus. Anatomically, it is adjacent to the third ventricle and many of its neurons project to the posterior pituitary. These projecting neurons secrete oxytocin and a smaller ...
, release
vasopressin Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travel ...
and
corticotropin releasing hormone Corticotropin-releasing hormone (CRH) (also known as corticotropin-releasing factor (CRF) or corticoliberin; corticotropin may also be spelled corticotrophin) is a peptide hormone involved in stress (biology), stress responses. It is a releasing ...
, which travel through the hypophysial portal vessel where they travel to and bind to the
corticotropin-releasing hormone receptor Corticotropin-releasing hormone receptors (CRHRs), also known as corticotropin-releasing factor receptors (CRFRs) are a G protein-coupled receptor family that binds corticotropin-releasing hormone (CRH). There are two receptors in the family, ...
on the
anterior pituitary gland A major organ of the endocrine system, the anterior pituitary (also called the adenohypophysis or pars anterior) is the glandular, anterior lobe that together with the posterior lobe (posterior pituitary, or the neurohypophysis) makes up the p ...
. 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 Melanocortin receptors are members of the rhodopsin family of 7-transmembrane G protein-coupled receptors. There are five known members of the melanocortin receptor system each with differing specificities for melanocortins: * . MC1R is associat ...
, where it stimulates the release of
steroid hormones A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Withi ...
. Steroid hormones bind to
glucocorticoid receptors Steroid hormone receptors are found in the nucleus, cytosol, and also on the plasma membrane of target cells. They are generally intracellular receptors (typically cytoplasmic or nuclear) and initiate signal transduction for steroid hormones which ...
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 In the human brainstem, the solitary nucleus, also called nucleus of the solitary tract, nucleus solitarius, and nucleus tractus solitarii, (SN or NTS) is a series of purely sensory nuclei (clusters of nerve cell bodies) forming a vertical column ...
, and
lamina terminalis The median portion of the wall of the forebrain consists of a thin lamina, the lamina terminalis, which stretches from the interventricular foramen (Foramen of Monro) to the recess at the base of the optic stalk (optic nerve) and contains the vas ...
. Through these inputs, it receives and can respond to changes in blood. The PVN innervation from 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 Neuropeptide Y (NPY) is a 36 amino-acid neuropeptide that is involved in various physiological and homeostatic processes in both the central and peripheral nervous systems. NPY has been identified as the most abundant peptide present in the ma ...
, which stimulates HPA axis activity. Generally, the amygdala stimulates, and the prefrontal cortex and hippocampus attenuate, HPA axis activity; however, complex relationships do exist between the regions. The
immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
may be heavily influenced by stress. The sympathetic nervous system innervates various immunological structures, such as
bone marrow Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic ce ...
and the
spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .
, 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 Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
.


Effects of 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 The adaptive immune system, also known as the acquired immune system, is a subsystem of the immune system that is composed of specialized, systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system ...
. This type of stress saw in increase in
granulocytes Granulocytes are cells in the innate immune system characterized by the presence of specific granules in their cytoplasm. Such granules distinguish them from the various agranulocytes. All myeloblastic granulocytes are polymorphonuclear. They ha ...
,
natural killer cells Natural killer cells, also known as NK cells or large granular lymphocytes (LGL), are a type of cytotoxic lymphocyte critical to the innate immune system that belong to the rapidly expanding family of known innate lymphoid cells (ILC) and represen ...
, IgA,
Interleukin 6 Interleukin 6 (IL-6) is an interleukin that acts as both a pro-inflammatory cytokine and an anti-inflammatory myokine. In humans, it is encoded by the ''IL6'' gene. In addition, osteoblasts secrete IL-6 to stimulate osteoclast formation. Smooth ...
, and an increase in cell cytotoxicity. Brief naturalistic stressors elicit a shift from Th1(cellular) to Th2(humoral) immunity, while decreased
T-cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...
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, your body metabolizes the food in a certain way that adds extra calories to your meal, regardless of the nutritional values of the food.


Infectious

Some studies have observed increased risk of
upper respiratory tract infection An upper respiratory tract infection (URTI) is an illness caused by an acute infection, which involves the upper respiratory tract, including the nose, sinuses, pharynx, larynx or trachea. This commonly includes nasal obstruction, sore thro ...
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 Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
, 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 Wound healing refers to a living organism's replacement of destroyed or damaged tissue by newly produced tissue. In undamaged skin, the epidermis (surface, epithelial layer) and dermis (deeper, connective layer) form a protective barrier again ...
. 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 In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland, about the size of a chickpea and weighing, on average, in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The ...
's production of growth hormone, as in children associated with a home environment involving serious marital discord,
alcoholism Alcoholism is, broadly, any drinking of alcohol (drug), alcohol that results in significant Mental health, mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognize ...
, or
child abuse Child abuse (also called child endangerment or child maltreatment) is physical, sexual, and/or psychological maltreatment or neglect of a child or children, especially by a parent or a caregiver. Child abuse may include any act or failure to a ...
. Chronic stress also has a lot of illnesses and health care problems other then 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 Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
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 Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...
, including cortisol, which are
steroid hormones A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Withi ...
that the
adrenal gland The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex which ...
releases, although this can increase storage of flashbulb memories it decreases long-term potentiation (LTP).Kalat, J. W. (2013). Biological Psychology. p. 383 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 Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, attitudes, and preferences. The ability to learn is possessed by humans, animals, and some machine learning, machines ...
, and decreased task flexibility and spatial
working memory Working memory is a cognitive system with a limited capacity that can hold information temporarily. It is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-term 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 Fibromyalgia (FM) is a medical condition defined by the presence of chronic widespread pain, fatigue, waking unrefreshed, cognitive symptoms, lower abdominal pain or cramps, and depression. Other symptoms include insomnia and a general hyp ...
,
chronic fatigue syndrome Chronic fatigue syndrome (CFS), also called myalgic encephalomyelitis (ME) or ME/CFS, is a complex, debilitating, long-term medical condition. The causes and mechanisms of the disease are not fully understood. Distinguishing core symptoms are ...
, depression, as well as other mental illnesses and functional somatic syndromes.


Psychological concepts


Eustress

Selye published in year 1975 a model dividing stress into
eustress Eustress means beneficial stress—either psychological, physical (e.g., exercise), or biochemical/radiological (hormesis). The term was coined by endocrinologist Hans Selye, consisting of the Greek prefix '' eu-'' meaning "good", and ''stress'', ...
and distress. Where stress enhances function (physical or mental, such as through
strength training Strength training or resistance training involves the performance of physical exercises that are designed to improve strength and endurance. It is often associated with the lifting of weights. It can also incorporate a variety of training te ...
or challenging work), it may be considered eustress. Persistent stress that is not resolved through coping or adaptation, deemed distress, may lead to
anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
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

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 In psychology, stress is a feeling of emotional strain and pressure. Stress is a type of psychological pain. Small amounts of stress may be beneficial, as it can improve athletic performance, motivation and reaction to the environment. Exces ...
, 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 Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...
, bright light, noise, temperatures, or environmental issues such as a lack of control over environmental circumstances, such as
food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
, air and/or water quality,
housing Housing, or more generally, living spaces, refers to the construction and assigned usage of houses or buildings individually or collectively, for the purpose of shelter. Housing ensures that members of society have a place to live, whether it ...
,
health Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiza ...
,
freedom Freedom is understood as either having the ability to act or change without constraint or to possess the power and resources to fulfill one's purposes unhindered. Freedom is often associated with liberty and autonomy in the sense of "giving on ...
, or mobility. * Social issues can also cause stress, such as struggles with
conspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organ ...
or difficult individuals and
social defeat Social defeat is a concept used in the study of the physiological and behavioral effects of hostile interactions among either conspecific animals, or humans, in either a dyadic or in a group-individual context, potentially generating very signific ...
, or relationship conflict,
deception Deception or falsehood is an act or statement that misleads, hides the truth, or promotes a belief, concept, or idea that is not true. It is often done for personal gain or advantage. Deception can involve dissimulation, propaganda and sleight o ...
, or
break up A relationship breakup, breakup, or break-up is the termination of a relationship. The act is commonly termed "dumping omeone in slang when it is initiated by one partner. The term is less likely to be applied to a married couple, where a bre ...
s, and major events such as
birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...
and
death Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...
s,
marriage Marriage, also called matrimony or wedlock, is a culturally and often legally recognized union between people called spouses. It establishes rights and obligations between them, as well as between them and their children, and between ...
, and
divorce Divorce (also known as dissolution of marriage) is the process of terminating a marriage or marital union. Divorce usually entails the canceling or reorganizing of the legal duties and responsibilities of marriage, thus dissolving the ...
. * Life experiences such as
poverty Poverty is the state of having few material possessions or little income. Poverty can have diverse social, economic, and political causes and effects. When evaluating poverty in ...
,
unemployment Unemployment, according to the OECD (Organisation for Economic Co-operation and Development), is people above a specified age (usually 15) not being in paid employment or self-employment but currently available for Work (human activity), w ...
,
clinical depression Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introdu ...
,
obsessive compulsive disorder Obsession may refer to: Psychology * Celebrity worship syndrome, obsessive addictive disorder to a celebrity's personal and professional life * Fixation (psychology), a persistent attachment to an object or idea * Idée fixe (psychology), a preo ...
, heavy drinking, or insufficient
sleep Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...
can also cause stress. Students and workers may face performance pressure stress from
exams An examination (exam or evaluation) or test is an educational assessment intended to measure a test-taker's knowledge, skill, aptitude, physical fitness, or classification in many other topics (e.g., beliefs). A test may be administered verb ...
and project deadlines. * Adverse experiences during
development Development or developing may refer to: Arts *Development hell, when a project is stuck in development *Filmmaking, development phase, including finance and budgeting *Development (music), the process thematic material is reshaped * Photograph ...
(e.g. prenatal exposure to maternal stress, poor attachment histories,
sexual abuse Sexual abuse or sex abuse, also referred to as molestation, is abusive sexual behavior by one person upon another. It is often perpetrated using force or by taking advantage of another. Molestation often refers to an instance of sexual assa ...
) 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 The Holmes and Rahe stress scale () is a list of 43 stressful life events that can contribute to illness. The test works via a point accumulation score which then gives an assessment of risk. The American Institute of Stress for instance, regards ...
.


General adaptation syndrome

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 phases: the ''shock'' phase and the ''antishock'' phase. * ''Shock phase'': During this phase, the body can endure changes such as hypovolemia, hypoosmolarity,
hyponatremia Hyponatremia or hyponatraemia is a low concentration of sodium in the blood. It is generally defined as a sodium concentration of less than 135 mmol/L (135 mEq/L), with severe hyponatremia being below 120 mEq/L. Symptoms can be abs ...
,
hypochloremia Hypochloremia (or Hypochloraemia) is an electrolyte disturbance in which there is an abnormally low level of the chloride ion in the blood. The normal serum range for chloride is 97 to 107 mEq/L. It rarely occurs in the absence of other abno ...
,
hypoglycemia Hypoglycemia, also called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's triad is used to properly identify hypoglycemic episodes. It is defined as blood glucose belo ...
—the stressor effect. This phase resembles
Addison's disease Addison's disease, also known as primary adrenal insufficiency, is a rare long-term endocrine disorder characterized by inadequate production of the steroid hormones cortisol and aldosterone by the two outer layers of the cells of the adre ...
. The organism's resistance to the stressor drops temporarily below the normal range and some level of shock (e.g.
circulatory shock Shock is the state of insufficient blood flow to the Tissue (biology), tissues of the body as a result of problems with the circulatory system. Initial symptoms of shock may include weakness, fast heart rate, fast breathing, sweating, anxiety, a ...
) 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 The locus coeruleus () (LC), also spelled locus caeruleus or locus ceruleus, is a nucleus in the pons of the brainstem involved with physiological responses to stress and panic. It is a part of the reticular activating system. The locus coerule ...
and sympathetic nervous system activate the production of catecholamines including adrenaline, engaging the popularly-known
fight-or-flight response The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first des ...
. Adrenaline temporarily provides increased muscular tonus, increased blood pressure due to
peripheral vasoconstriction Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vessel ...
and
tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (su ...
, and increased glucose in blood. There is also some activation of the
HPA axis HPA may refer to: Organizations * Harry Potter Alliance, a charity * Halifax Port Authority, Canada * Hamburg Port Authority, Germany * Hawaii Preparatory Academy, a school in Hawaii, US * Health Protection Agency, UK * Heerespersonalamt, the Ger ...
, producing glucocorticoids (cortisol, aka the S-hormone or stress-hormone).


Stage 2

''Resistance'' is the second stage. During this stage, increased secretion of
glucocorticoids Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...
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 Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances ( electrolyte balance and fluid balance). The primary ...
(
aldosterone Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a c ...
) 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 The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies viscera, internal organs, smooth muscle and glands. The autonomic nervous system is a control ...
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 Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...
which in turn leads to cell necrosis), as the body's immune system becomes exhausted, and bodily functions become impaired, resulting in
decompensation In medicine, decompensation is the functional deterioration of a structure or system that had been previously working with the help of compensation. Decompensation may occur due to fatigue, stress, illness, or old age. When a system is "compensate ...
. The result can manifest itself in obvious illnesses, such as general trouble with the
digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...
(e.g. occult bleeding, melena,
constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...
/obstipation),
diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
, or even
cardiovascular The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
problems (
angina pectoris Angina, also known as angina pectoris, is chest pain or pressure, usually caused by insufficient blood flow to the heart muscle (myocardium). It is most commonly a symptom of coronary artery disease. Angina is typically the result of obstru ...
), along with
clinical depression Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introdu ...
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.


History in research

The current usage of the word ''stress'' arose out of
Hans Selye János Hugo Bruno "Hans" Selye (; hu, Selye János; January 26, 1907 – October 16, 1982) was a pioneering Hungarian-Canadian endocrinologist who conducted important scientific work on the hypothetical non-specific response of an organism to s ...
'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 Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
and he undertook extensive research programs and publication efforts. While the work attracted continued support from advocates of
psychosomatic medicine Psychosomatic medicine is an interdisciplinary medical field exploring the relationships among social, psychological, behavioral factors on bodily processes and quality of life in humans and animals. The academic forebear of the modern field of ...
, 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 Biopsychosocial models are a class of trans-disciplinary models which look at the interconnection between biology, psychology, and socio-environmental factors. These models specifically examine how these aspects play a role in topics ranging from ...
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 A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). Ci ...
. Selye coined the term "
eustress Eustress means beneficial stress—either psychological, physical (e.g., exercise), or biochemical/radiological (hormesis). The term was coined by endocrinologist Hans Selye, consisting of the Greek prefix '' eu-'' meaning "good", and ''stress'', ...
" 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 The tobacco industry comprises those persons and companies who are engaged in the growth, preparation for sale, shipment, advertisement, and distribution of tobacco and tobacco-related products. It is a global industry; tobacco can grow in any ...
from 1958 and they were undeclared allies in
litigation - A lawsuit is a proceeding by a party or parties against another in the civil court of law. The archaic term "suit in law" is found in only a small number of laws still in effect today. The term "lawsuit" is used in reference to a civil actio ...
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 A psychologist is a professional who practices psychology and studies mental states, perceptual, cognitive, emotional, and social processes and behavior. Their work often involves the experimentation, observation, and interpretation of how indi ...
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 Neuroendocrine cells are cells that receive neuronal input (through neurotransmitters released by nerve cells or neurosecretory cells) and, as a consequence of this input, release messenger molecules ( hormones) into the blood. In this way they b ...
, molecular, and
immunological Immunology is a branch of medicineImmunology for Medical Students, Roderick Nairn, Matthew Helbert, Mosby, 2007 and biology that covers the medical study of immune systems in humans, animals, plants and sapient species. In such we can see there ...
bases of stress, conceived as a useful
heuristic A heuristic (; ), or heuristic technique, is any approach to problem solving or self-discovery that employs a practical method that is not guaranteed to be optimal, perfect, or rational, but is nevertheless sufficient for reaching an immediate, ...
not necessarily tied to Selye's original hypotheses. The
US military The United States Armed Forces are the Military, military forces of the United States. The armed forces consists of six Military branch, service branches: the United States Army, Army, United States Marine Corps, Marine Corps, United States N ...
became a key center of stress research, attempting to understand and reduce combat
neurosis Neurosis is a class of functional mental disorders involving chronic distress, but neither delusions nor hallucinations. The term is no longer used by the professional psychiatric community in the United States, having been eliminated from th ...
and psychiatric casualties. The
psychiatric Psychiatry is the medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders. These include various maladaptations related to mood, behaviour, cognition, and perceptions. See glossary of psychiatry. Initial psy ...
diagnosis ''
post-traumatic stress disorder Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats on ...
'' (''PTSD'') was coined in the mid-1970s, in part through the efforts of anti-Vietnam War activists and the
Vietnam Veterans Against the War Vietnam Veterans Against the War (VVAW) is an American tax-exempt non-profit organization and corporation founded in 1967 to oppose the United States policy and participation in the Vietnam War. VVAW says it is a national veterans' organization ...
, and
Chaim F. Shatan Chaim F. Shatan (September 1, 1924 – August 17, 2001) was a Jewish-Canadian psychiatrist born in Włocławek, Poland. Shatan's parents moved to Canada when he was two. He received his MDCM degree from McGill University in Montreal, Quebec, ...
. The condition was added to the ''
Diagnostic and Statistical Manual of Mental Disorders The ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM; latest edition: DSM-5-TR, published in March 2022) is a publication by the American Psychiatric Association (APA) for the classification of mental disorders using a common langua ...
'' as ''posttraumatic stress disorder'' in 1980.
on-line
.
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 Occupational stress is psychological stress related to one's job. Occupational stress refers to a chronic condition. Occupational stress can be managed by understanding what the stressful conditions at work are and taking steps to remediate thos ...
, and stress management techniques were developed. The term also became a
euphemism A euphemism () is an innocuous word or expression used in place of one that is deemed offensive or suggests something unpleasant. Some euphemisms are intended to amuse, while others use bland, inoffensive terms for concepts that the user wishes ...
, a way of referring to problems and eliciting
sympathy Sympathy is the perception of, understanding of, and reaction to the distress or need of another life form. According to David Hume, this sympathetic concern is driven by a switch in viewpoint from a personal perspective to the perspective of ano ...
without being explicitly confessional, just "stressed out". It came to cover a huge range of phenomena from mild
irritation Irritation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant. Irritants are typically thought of as chemical age ...
to the kind of severe problems that might result in a real breakdown of
health Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiza ...
. 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".


See also

*
Autonomic nervous system The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies viscera, internal organs, smooth muscle and glands. The autonomic nervous system is a control ...
*
Defense physiology Defense physiology is a term used to refer to the symphony of body function (physiology) changes which occur in response to a stress or threat. When the body executes the "fight-or-flight" reaction or stress response, the nervous system initiates ...
*
HPA axis HPA may refer to: Organizations * Harry Potter Alliance, a charity * Halifax Port Authority, Canada * Hamburg Port Authority, Germany * Hawaii Preparatory Academy, a school in Hawaii, US * Health Protection Agency, UK * Heerespersonalamt, the Ger ...
* Trier social stress test *
Xenohormesis Xenohormesis is a hypothesis that posits that certain molecules such as plant polyphenols, which indicate stress in the plants, can have a longevity-conferring effect in consumers of plants (i.e. mammals) and studies that relationship. It was first ...
* Stress in early childhood *
Weathering hypothesis The weathering hypothesis was proposed to account for early health deterioration as a result of cumulative exposure to experiences of social, economic and political adversity. It is well documented that minority groups and marginalized communities ...


References


External links


The American Institute of Stress"Research on Work-Related Stress"
European Agency for Safety and Health at Work The European Agency for Safety and Health at Work (EU-OSHA) is a decentralised agency of the European Union with the task of collecting, analysing and disseminating relevant information that can serve the needs of people involved in safety and h ...
(EU-OSHA)
Coping With StressStages of GAS & Evolving the Definition
{{Authority control Stress (biology) Endocrine system Sympathetic nervous system