Chapter 2: Homeostasis and Adaptive Responses to Stressors

Allostatic overload

"cost" of body's organs and tissues for an excessive or ineffectively regulated allostatic response Effect of "wear & tear" on the body

General Adaptation Syndrome (GAS)

3 stages Alarm Resistance/ Adaptation Exhaustion

Resistance or Adaptation Stage

Activity of the nervous and endocrine systems in returning the body to homeostasis SNS and adrenal medulla and cortex are functioning at full force to mobilize resources to manage the stressor

Allostatic State

Activity of various systems attempting to restore homeostasis

Sex hormones

Affect stress responses, thus influencing allostasis May help explain gender responses during responses during stress Ex: estrogen, testosterone & dehydroepiandrosterone

Stressors

Agents or conditions that can produce stress Endanger homeostasis May be external or internal Physical, chemical, biological, social, cultural or psychological Vary in scope, intensity and duration

Selye's three phases of stress response include all of the following

Alarm Resistance Exhaustion

Emotional indicators of high stress

Anxiety Depression Increased use of mind altering substances Changing in eating sleeping or activity pattern Mental exhaustion Increased irritability Loss of motivation Increased illness

Coping

Behavior adaptive response to a stressor using culturally based coping mechanisms

Which of the following is an example of a stressor?

Being exposed to air pollution

Growth hormone

Can increase during stress to enhance immune function

Stress induced hormones

Cortisol Norepinephrine Epinephrine

Adrenocortical Steroids

Critical to maintenance of homeostasis May synergies or antagonize effects of catecholamines EX: cortisol & aldosterone

Physical indicators of high stress

Elevated BP Increased muscle tension Elevated pulse rate Increased respiration Sweaty palms Cold extremities Fatigue Tension headache

Stress response mediated by catecholamines

Elevation of cardiac output Vasomotor changes Lipolysis Glycogenolysis Insulin suppression Increased respiration Enhanced blood coagulation

Endorphins & Enkephalins

Endogenous (produces inside body) opioids Body natural pain relievers Raise pain threshold Produce sedation and euphoria

The primary adaptive purpose of the alarm stage is

Energy and repair

Epinephrine

Enhances myocardial contractility Increases HR & Increases C.O Causes bronchodilation Increases the release of glucose from liver (glycogenolysis) Elevates blood glucose levels

Alarm stage

Fight or flight response due to stressful stimulus Provides a surge of energy and physical alterations to either evade or confront danger

Reactions to stress vary depending upon:

Genetic constitution Gender Past experiences Cultural influences Developmental stage Age

Effects of stress response influenced by:

Genetics Socioeconomic status Prior susceptibilities Preexisting health status Allostatic state Ability to manage stress

Adaptation methods for stress

Habituation Desensitization Biofeedback Visualization Mediation

Allostatic overload results

Inability to maintain homeostasis Leads to various illnesses and disorders (physical and emotional) Chemical mediators from the stress response contribute to various illness: Cortisol, catecholamines, cytokines

A physiologic response to the release of catecholamines during the stress response would be:

Increased glycogenolysis & gluconeogensis

Norepinephrine

Increases HR and contractility Constricts blood vessels to decrease blood flow to less essential tissues and organs Raise BP Reduces gastrointestinal motility & gastric secretion Dilates the pupils Inhibits insulin secretion

Which is not normally secreted in response to stress?

Insulin

Many of the responses to stress are attributed to the activation of the SNS and are mediated by

Norepinephrine

Distress

Perceived inability to cope with a stressor

Catecholamines

Play important role in allostasis Sympathico-adrenal system response Mediates fight or flight response EX: NE, E

Exhaustion

Point where body can no longer return to homeostasis

Cortisol (STRESS HOROMONE)

Primary glucocorticoid Affects protein metabolism Promotes appetite and food seeking behaviors Has anti- inflammatory effects

Cortisol

Primary glucocorticoid Secreted by adrenal cortex in response to ACTH from anterior pituitary Anabolic effect leading to increased rates of protein synthesis in the liver Catabolic effect in muscle, lymphoid and adipose tissue and on skin and bone Immune suppression

Aldosterone

Primary mineralcorticoid Promotes reabsorption of sodium and water Increases blood pressure Increased extracellular fluid volume Stimulation of SNS activates the renin- angiotensin system and the release of aldosterone is the final chemical outcome Increase in the secretion of potassium

Oxytocin

Produced during childbirth and lactation Associated with bonding and social attachment Thought to moderate stress response & produce a calming effect

Indicators that an individual is experiencing high stress include all of the following except

Pupil constriction Eyes contract radial muscle to dilate iris and pupil

Allostatic overload accumulates in an individual

Repeated exposures to multiple stressors Inability to habituate or adapt to the stressor Unnecessarily prolonged stress response or stress response that continues after the stressor is removed Inadequate response to the stressor that causes other stress response mediators to attempt to compensate

Which stage of the GAS facilitates the individuals allostatic restoration of homeostasis?

Resistance

Role of hypothalamus in a stressful situation

SNS activated Release of Epinephrine from adrenal medulla Body will release more glucose Hypothalamus release corticotrophin releasing hormone (CRH) CRH stimulates the anterior pituitary to release glucococorticoids Raised blood sugar

Immune cytokines

Secreted by macrophages during stress response Enhance immune system response Prolonged stress can suppress immune functioning Ex: Interleukin- 1

Activation of which two systems occurs in response to a stressor?

Sympathetic adrenal medullary system (vigilant states) Hypothalamic pituitary axis (glucocorticoid response)

Allostasis is best defined as

The overall process of adaptive change necessary to maintain survival and well being

Allostasis

ability to successfully adapt to challenges Regulatory processes orchestrated by the brain Maintains/ reestablishes homeostasis

Adaptation

biopsychosocial process of change ind response to new or altered circumstances Internal or external in origin

Stress response mediated by corticosteroids

gluconeogenesis protein catabolism Inhibition of glucose intake Suppression of protein synthesis Stabilization of vascular reactivity Immune response suppression