General Adaptation Syndrome (GAS) – Stages, Phases, Treatment

What is General Adaptation Syndrome?

General adaptation syndrome is a theorized physiological response to stress developed by Hans Selye. This theory was developed after experimenting and observing the physiologic responses of animals to stress. Hans Selye observed that animals subject to stress emerged with enlarged adrenal cortex, atrophied thymus, spleen, lymph nodes and other lymphatic structures and ulcers in the stomach and duodenum. He then identified these as nonspecific reactions to multiple, diverse and noxious stimuli (stress), and developed the theory of General Adaptation Syndrome.


Leaky Gut Syndrome

Characteristics of General Adaptation Syndrome (GAS)

GAS is characterized by responses that are non-specific and involves the whole body. General adaptation syndrome is different from Local Adaptation Syndrome (LAS) which is another physiologic response to stress. LAS is a more specific response and involves inflammation on a specific or local site in the body.

General Adaptation Syndrome Stages & Phases

Under stress, a person may have a general response to the stressful stimuli. One of the responses can be the general adaptation syndrome. General adaptation syndrome involves three phases or stages.

  • Alarm Phase

This stage is marked by the activation of the “fight and flight”  response, the release of catecholamines and the release of the adrenocorticotropic hormone. This stage is also characterized by a defensive and anti-inflammatory response. Prolonged exposure to the alarm phase is lethal to the human system, and so the body enters to another stage.

  • Resistance Phase

In this stage, the adaptation to the stressor or noxious stimuli occurs. This stage is still marked by an increase in cortisol levels (from the release of adrenocorticotropic hormone).

  • Exhaustion Phase

Prolonged exposure to stress results to the stage of exhaustion, this stage has dangerous effects to the human body particularly the digestive, immune and circulatory system. When a person is left untreated, and stays at this stage for a prolonged period of time, the result can be death.

General Adaptation Syndrome pics

The General Adaptation Syndrome


General Adaptation Syndrome Symptoms

When a person responds to stress through general adaptation, his/her body activates certain physiologic responses. From these activated responses, we can appreciate the signs of General Adaptation Syndrome (GAS). It is important to note that GAS do not have specific signs or symptoms, but the presence of certain responses and the duration of these responses may indicate the person is indeed in that state of physiologic response to stress.

The Hypothalamic-Pituitary Responses

As stated earlier, stress induces several responses in the body, one system that is activated due to stress is the hypothalamic-pituitary axis. Once this system is activated, different physiologic reactions follow.

Increase production and release of cortisol

This is due to the stimulation of the hypothalamus to secrete Corticotropin Releasing Factor; this then signals the pituitary gland to secrete ACTH (adenocorticotropic hormone) which signals the adrenals to release cortisol. The increases in cortisol levels have the following effects:

  • Breakdown of Protein (protein catabolism)
  • Gluconeogenesis or the conversion of amino acids to glucose
  • Anti-insulin action of many body cells except the brain and the heart

Release of Antidiuretic Hormone

Another hormone released via the activation of the hypothalamic-pituitary axis is antidiuretic hormone or ADH. This hormone has the following actions:

  • Sodium and water retention to prevent loss of fluid in cases of hemorrhage or excessive perspiration

  • Cyclic Vomiting Syndrome

  • Has an effect on learning and coping

The Sympathetic- Adrenal Response

Aside from the hypothalamic-pituitary axis, stress and general adaptation syndrome also activates a sympathetic-adrenal response. This in turn causes a myriad of responses, signs and symptoms relating to stress and general adaptation syndrome.

  • Increase blood pressure and heart rate
  • Alertness and increased mental acuity
  • Pupil dilation
  • Increased level of blood glucose
  • Increase muscle tone
  • Increased rate of breathing
  • Increased blood coagulation

Immune Responses

Stress responses also exert significant effects to the immune system. These may include:

Initial Stage

  • Increase number of immune cells (WBC, lymphocytes) to help the body fight the stress (whether that is infection or injury) and regulate inflammation
  • Activation of the inflammatory response such as vasodilation (widening of the blood vessels) to allow the immune cells to the site of injury, stress or inflammation

Late stage

  • Decreased number of immune cells, predisposing the person of infections
  • Vasoconstriction which causes decrease blood supply in areas of the body

images of General Adaptation Syndrome symptoms

The Responses of the Body to Stress

Once activated, such responses to stress are actually helpful to the body, these signs and symptoms serve as the body’s mechanism to fight stress. For example, the increase in gluconeogenesis and protein catabolism promotes higher levels of energy. However when these responses are prolonged and remained unresolved, their effects can be deleterious. Example, prolonged exposure to increased levels of cortisol depresses the immune system; this then puts the person into higher risk of acquiring infection since the body’s defenses are inhibited.

General Adaptation Syndrome (GAS) Causes

The primary cause of GAS is stress. Stress can come in two forms:

Physical stress

  • Injuries
  • Trauma
  • Fall
  • Allergic reactions (hypesensitivity reactions)
  • Infections
  • Other disease conditions

Psychological Stress

  • Work
  • Studying
  • Depression
  • Traumatic incidences such as witnessing accidents
  • Employment
  • Life events such as divorce, graduation, retirement, etc.

Stress is considered a stimulus, and people deal with it everywhere and in everyday of their lives. Because it is a stimulus, it helps keep people going and serves as a motivating factor for people’s activities. Like other stimuli, stress can also come in good and bad forms.

  • Eustress- considered as “the good stress”
  • Distress- is a noxious type of stimuli or stress

General Adaptation Syndrome Treatment and Prevention

Treatment usually focuses on the management of stress. The goal of stress management is to allow the person to adapt healthy coping mechanisms that will help him/her deal with the stress.

Incorporating a healthy lifestyle

  • Exercise
  • Balanced diet
  • Proper time management that allows enough rest and sleep
  • Avoidance of smoking and drinking (maladaptive behaviors)
  • Strengthening relationships
  • Improvement of social skills

Enhance Coping Strategies

  • Having a positive outlook
  • Use of social and spiritual support
  • Acceptance of a stressful situation
  • Maintaining control over feelings or the situation
  • Relaxation Techniques
  • Progressive muscle relaxation
  • Benson’s Relaxation Response
  • Guided Imagery

General Adaptation Syndrome Life Expectancy

Stress had been coined as the “mother of all diseases”, people who experience enormous stress and those who have unhealthy ways to cope or relieve stress have the higher risk of developing stress related disease conditions such as heart disease, diabetes and cancer. The comorbidities that accompany prolonged exposure to stress affect the life expectancy significantly.


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