The word stress in English originally meant "stress, tension". In many languages (including Czech), the word stress has become a synonym for psychic stress at a stage when it is already unpleasant - mental stress in the exhaustion phase. This text does not deal with acute mental stress. If you suffer from acute psychological stress , try to check out here.
This text deals with stress in the wider sense of the word. Stress in the wider sense of the word is inseparably linked to the famous physiologist of the 20th century, Jánoszem (Hans) Sely . Calling Selye's "father of stress" (see Battistuzzi2011hsf ) is not entirely right - Jánosz (Hans) Selye should rather be called the creator of the so-called unified theory of medicine . That you have never heard of any unified theory of medicine? Do not do anything about it, theoretical medicine is not being taught at medical schools ...
Selye's contribution - from stress to theoretical medicine
Jánosz (Hans) Selye introduced the word stress into the general consciousness in 1936 by the article "A Syndrome Produced by Various Nightuous Agents" ( Nature ). Selye has developed a theory of generalized stress and described a so-called generalized adaptation syndrome - a non-specific hormonal reaction in which the organism reacts to various stressful stimuli uniformly by spilling out adrenaline, noradrenaline and cortisol . Cortisol is considered to be a stress hormone. Adrenaline (epinephrine) and noradrenaline (norepinephrine) are considered as "attack and escape hormones".
In this example, Selye understood that the norms of physiology and medicine could be generalized. It's not as easy as physics, but it's possible. Selye has therefore tried to generalize the definition of health, homeostasis, stress, adaptation range, and so on. In doing so, he created the basics of the science sector, which he called the unified theory of medicine . It is a complex, though problematic theory - as well as evolutionary theory in biology, where we have defined definitions of fitness, evolutionary pressure, genetic drift, and so on.
The benefits of Selye can be chanting long, as is the case in Szabo2012lhs , but the truth is that in the 20th century, after Selye's departure, theoretical medicine as a branch did not develop. Selye became known for his experimental discoveries (cortisol), and theoretical medicine remained largely unaware until the 21st century. Let us recall that the concept of adaptogen belongs to the field of theoretical medicine as well.
Eustres, distress and generalized adaptation syndrome (GAS)
Finally, we present a brief outline of the generalized adaptation syndrome in humans. You may have already heard Selye's terms eustres and distres . Simply put, the eustres with the Greek prefix of eu- is stress until it is "good". Eustres activates us and gives us better performance. Distres is a situation where our forces are not enough for the current burden - the burden exceeds our adaptation range. In his publications ( Selye1950sga , Selye1950ars and others), Janos Selye divided the stress response into two types:
- specific stress response - is directly related to the stressor and varies according to the type of stress. Example: While wearing heat, we sweat, we have cold goose skin and create warmth with muscle tremors. If the heat load exceeds our adaptation range, we get sunburn or freeze.
- non-specific stress response - is the same for each type of load. Example: Whether it is a heat load or problems with a boss at work, both result in increased cortisol levels. Another example: Whether cellular stress caused by heat, radiation or poisons, the result is increased expression of so-called chaperons.
The smarter one is already clear how the concept of stress can be generalized. Selye expressed it as a generalized adaptation syndrome . Generalized adaptation syndrome has three phases:
- Phase Alarm - Acute Stress Reaction. Example: After seeing the wolf, we sneeze, we get hairs, the adrenal glands immediately release the dose of adrenaline and noradrenaline and we start running.
- the stage of adaptation - phase, when our strength is enough to handle the stressful situation. Example: The Marathon runner runs at a speed of 20km / h over long distances.
- the depletion phase - or so-called decompensation. Example: A man fleeing the wolf loses his breath after a few hundred meters, has to stop running and he is facing a state of exhaustion. Another example: After 1 hour of staying in frozen seawater, a person dies of hypothermia.
These three phases of generalized adaptation syndrome can be noticed not only in humans but also in animals and even in unicellular animals. In humans, however, these stress response phases correspond to typical hormonal responses that drive the so-called hypothalamic-pituitary, or stress axis. The main stress hormones are
- CRH (corticotropin releasing hormone, cortikoliberin), which is created in the brain
- ACTH (adrenocorticotropic hormone), which is formed in the pituitary gland and is then poured into the bloodstream
- adrenaline , noradrenaline and cortisol , which are formed in the adrenal glands and released into the bloodstream
While adrenaline (epinephrine) and noradrenaline (norepinephrine) are typical of the first (alarm) phase of the stress reaction (falling into cold water, inappropriate arrival of a police officer, etc.), the actual stress hormone is cortisol.
The acute stress reaction in Selye's sense takes several hours during which an individual devotes all his or her survival strengths, sometimes at the cost of a certain self-harm. If stress stress ( Mcewen2000aal ) does not exceed the body's adaptation range, it will adapt to the shorter or longer time and enter the adaptation phase . In the adaptation phase, the body produces an increased amount of energy, but it can tolerate the constant burden without any further damage. The level of stress hormones (mainly cortisol) is increased but stable - the burden is fully compensated. Depending on the size of the body's load and resources, the duration of the adaptation phase may vary greatly. The depletion phase (decompensation) is characterized by depletion of the body's resources and the collapse of homeostasis. The level of stress hormones is rising again, but the body no longer has the burden, the body of melee from the last. When damage reaches a non-returnable point, death occurs.
With a load exceeding the adaptation range of the body many times, death can occur immediately without the development of an adaptation syndrome. Conversely, if the burden is sustained for a long time (within the long-term adaptation range), the depletion phase does not occur at all. The body reacts with physiological changes that allow for increased stress without suffering more damage. Example: The athlete's body adapts to increased movement demands by increasing muscle mass. Another example: Outdoors dog adapts easily to winter by cold adaptation. A slightly increased physical load does not generally damage the body - so sport is healthy. In contrast, chronic mental stress is not healthy. An alostatic burden of mental stress is detrimental to the body by increased cortisol levels and by immune changes that, along with nerve factors, can contribute to chronic depression , obesity , hypertension, and autoimmune disease .