Stress and General Adaptation Syndrome (GAS)

• Stress, general adaptation syndrome (GAS), and general alarm reaction indicate a physiological response, helping organisms adapt to fight or flee.
• The absence or excess of stress is harmful, while the optimum level is essential for life, growth, and survival.
• Three GAS phases are recognized: alarm, resistance, and exhaustion.
• The phases involve neural, neuroendocrine, and endocrine axes.
• The neural axis increases muscle tone, causes bodily paralysis, cortical alert reaction, and sympathetic discharge.
• The neuroendocrine axis secretes adrenaline and noradrenaline from the adrenal medulla.
• The endocrine axis activates the hypothalamus-hypophysis-adrenal cortex-cortisol axis.
• Cortisol is the primary stress hormone, short-term actions are essential, but long-term excess is harmful, causing organism failure and reducing resistance.
• Multiple pathologies are associated with stress, symptoms indicating emotional, behavioral, intellectual, and physical effects.

Introduction

• Stress is responsible for multiple pathologies.
• It's a natural body response to prepare for action or escape.
• Stressful stimuli (stressors) and physiological responses exist in daily life.
• Physiological responses are called stress, fight-or-flight response, general alarm reaction, or general adaptation syndrome.
• Stressful stimuli can be physical or psychological (mental or emotional).
• Common physical stimuli: trauma, chronic infections, intense heat or cold, surgeries, nociceptive stimuli (pain-producing), partial or total immobilization, sympathomimetic medications, childbirth, hemorrhage, severe hypoglycemia from fasting, allergies, and dehydration.
• Common psychological stimuli: strong emotions, love relationships, anxiety, family problems, and daily life situations.
• Spanish study in 1983 by González de Rivera and Morera assessed life events for their stress-producing capacity.

Stress, General Alarm Reaction, and General Adaptation Syndrome

• Stress is a physiological reaction to aversive or pleasant situations/stimuli (Walter Cannon).
• General Alarm Reaction prepares subjects to fight or flee.
• General Adaptation Syndrome (GAS) is a physiological response that helps organisms adapt, independent of the stimulus type.
• Hans Selye coined the term SGA, and considered the father of stress.
• The terms are synonymous: Stress, General Alarm Reaction, and General Adaptation Syndrome.
• The body's homeostasis regulation is vital (Claude Bernard).
• During stress, destabilizing forces occur, neutralized by physiological adaptations to maintain internal normalcy.

Types of Stress

• Hans Selye stated "some stress is essential and healthy; the optimal amount of stress is ideal, but too much stress is harmful."
• Two types of stress:
• Eutress: good, optimal stress, essential for life, growth and survival and is not harmful.
• Distress: harmful, pathological stress is accumulative, kills hippocampal neurons, produces mental pathologies, accelerates aging; effects can occur prenatally and inhibit fetal androgenization.

Relationship Between Stress and Performance

• Figure 1 shows the curve describing the relationship between stress and individual performance.
• Zone A-B: absence of stress, low performance, apathy, lack of stimuli and goals (no stress is bad).
• Zone B-C: optimal performance zone, subjects are motivated and satisfied.
• Zone C-D: excess stress zone, declines individual performance.
• Zone D-E: maximum stress zone, very low performance, the subject is depressed/anxious.
• Very low or maximum stress leads to low performance.

Phases of General Adaptation Syndrome (GAS)

• Alarm Phase
• Resistance Phase
• Exhaustion Phase
• Stages occur after perception/identification of the stimulus by the system.
• Stage one involves the nervous and endocrine system.

Alarm Phase

• Immediate perception of the stressing stimulus occurs.
• Freezing or paralysis can occur where the person can't move, caused by periaqueductal gray matter excitation.
• The amygdala causes cortical activation, releasing encephalic noradrenaline (NA).
• This cortical activation establishes a hyperacute consciousness where the individual identifies their environment thoroughly.
• Facial manifestations are the state of shock (cranial nerves V and VII involved).

Resistance Phase

• Maintenance of physiological activation to overcome or adapt to the threat - this may last weeks, months, or years, and can be considered chronic stress.
• In this phase, if the stress ceases, the body can return to a normal state.

Collapse/Exhaustion Phase

• The body’s resources are depleted, caused by frequent, repeated stressful stimuli.
• Pathologies occur related to stress: insomnia, poor concentration, depression, fatigue, immune, cardiovascular, metabolic, endocrine pathologies, gastrointestinal issues, cardiac and/or cerebral infarcts.
• Stress/SGA should not reach exhaustion, resistance should enable fighting/adapting without depleting response capacity (Figure 2).

Physiological Processes During SGA

Neural Axis

• Activated immediately upon perceiving the stressors and triggers the following:
• Freezing or paralysis occurs due to abrupt stimuli activating periaqueductal gray matter (PAG).
• The pontine reticular formation facilitates stretch/deep reflexes, induces hyperreflexia/hypertonia that mediate heightened muscle tone.
• Shock: facial expressions identify an individual's mood, aided by the trigeminal and facial nerves.
• Limbic system (amygdala) induces cortical alertness, which excites encephalic noradrenergic system in the locus coeruleus. The release of NA leads to heightened consciousness.
• Sympathetic nervous system discharges cause the release of noradrenaline (NA) and adrenaline (A) to the system, which causes hyperglycemia by glycogenolysis, elevated heart rate, cardiac output, vasoconstriction, increased sweating, respiration rate, and glucagon release.
• Healthy individuals return to normal within minutes without any negative impacts.

Neuroendocrine Axis

• Requires prolonged or intermittent stressor exposure.
• Signals are delayed but duration lasts longer.
• The hypothalamus activates sympathetic preganglionic neurons, stimulating the adrenal medulla to release A and NA into the blood.
• Adrenaline receptors on structures, support the initial sympathetic response.
• Hormonal processes take longer (minutes), leading to greater bodily preparedness.

Endocrine Axis

• Initiation is slower, duration lasts hours or days.
• The hypothalamus activates the hypothalamus-hypophysis-adrenal cortex axis causing the hippocampus to activate sympathetic nervous system, and adrenal medulla.
• Physical and emotional stressors (anxiety and depression), limbic system activations and amygdala, changes in the sleep cycle or diet, and neurotransmitters activate the hypothalamus, triggering nuclei paraventriculares.
• The nuclei paraventriculares synthesize and secrete corticotropin-releasing hormone (CRH).
• CRH stimulates the adrenohypophysis to synthesize the hormone adrenocorticotropic ACTH into the systemic blood system, increasing levels of glucocorticoid cortisol.
• Cortisol acts on cells because receptors are distributed.
• Reabsorption of Na+ and H2O and excretion of K+ by renal action happens during the action of glucorticoid cortisol.

Cortisol Feedback

• Released Cortisol from the adrenal cortex inhibits ACTH secretion in adenohypophysis and CRH in hypothalamus (long feedback loop).
• ACTH secretion from the hypothalamus inhibits CRH secretion (short feedback loop).
• Normal under-stress conditions.
• CRH-ACTH-Cortisol axis remains hyperactive during stress producing long lasting, stress induced bodily damage.
• Stressors generally act on the hypothalamus and increase CRH production while increasing NA and A released by the Locus Coeruleus.

Circadian Rhythm

• Under normal conditions but without stress, the cortisol and ACTH follow a circadian rhythm of secretion.
• The body is regulated for the fight or flight preparation of the body.

Gonadotropins

• Stress restricts FSH and LH which can cause women in stress to have amenorrhea.

Antidiuretic Hormone (ADH) / Vasopressin

• Increasing ADH levels in the blood and in stressed environment produces water reabsorption through urination in the renal tubules.

Glucagon Levels

• Elevates from sympathetic stimulation that elevates glycemia.

Oxytocin

• Stress in levels decreases levels and decreases breast milk production.

Short and Long Term Effects

• Short term acute stress, with short bursts of hormones, is essential for living.
• Long term activation is extremely damaging.

Phases of the Nervous and Endocrine System

• Rapid Responses
• Acute Responses
• Bodily Adaptation

Alarms Phase

• Shock
• Increased muscle tone and Paralysis
• Blood and Blood pressure and blood sugar will decrease

Second Phase Responses

• Sympathetic nervous system increases the following.
  • Blood pressure
  • Concentration of Glucose
  • Strength output
• Blood streams to the areas with the most physical usage.

Resistance Phase

• Body resists the stress and adapts to the environment. Cortisol and CRH increase to create balance.

Exhaustion

Distrés (Symptoms

• Exhaustion occurs from continual chronic stress.
• Nervous System and hormonal levels are not responding.
• There is an energy depletion from the lack of energy for the body to use.
• Selye creates three categories which can create too much stress.
• Emotional and behavioral issues. -Mood and behavior changes that can cause excessive changes.
• Thought problems Symptoms: Lack of awareness/focus, inability to retain details, poor concentration.
• Physical Ailments" Bodily Aches
• Examples: Dry mouth, physical fatigue, lack of bodily control.

Factors

• Two personality types: Vulnerable and resistant.
• Positive characteristics should be at a balance and should not be too similar.
• Balance should be at equilibrium, and not be lacking.

Control

Ambiguity

• Due to the world changing with technology, and locations becoming difficult from stress, must understand the need to adapt to different areas, people.

Good Surroundings

• Reliable friends with good work ethics.
• Good listeners and offers advice when the time is nessecary.

Positive reinforcement

Reduce Abuse

Be Positive

Sex

• Latin american countries where patriarchal ideas are still present cause extreme stress on women and create difficult environment.

Age

• Young individuals adapt much easier and quicker where there are very few complications or health risks.

Cellular

• Stress leaves damages and leaves superoxides which damage cells and create a difficult cellular environment.

Explore the physiology of stress, focusing on the General Adaptation Syndrome (GAS). Understand how stress, mediated by neural, neuroendocrine, and endocrine axes, affects the body's ability to adapt. Learn about the importance of balanced stress levels for optimal health and the adverse effects of prolonged stress.