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Learning Objectives
Chapters 7
Chapter 7, Stress and Adaptation
Learning Objective 1.
 Relate homeostasis to health.
 Define homeostasis and explain its importance to the body’s ability to maintain optimal function.
o Homeostasis: balance in the body (kept as a range)
o Body uses homeostasis to regulate water, blood glucose, temperature, pH; etc. levels in the body
all day, every day to maintain it at a consistent optimal level in response to changes in the
internal and external environment
 Using examples, differentiate negative and positive feedback mechanisms.
o Stimulus  receptor  control center  effector
o Negative feedback: goes against/opposes a stimulus to inhibit the original stimulus
 Ex: stimulus (cold)  shiver; stimulus (hot)  sweat (thermostat example)
o Positive feedback: goes with stimulus; enhances original stimulus
 Acute situations; good for you at that place, at that time
 Ex: keep running from danger, childbirth
 Describe stress, stressors, conditioning factors, and stages of general adaptation syndrome (GAS),
according to Selye.
o Stress can contribute directly to the onset and exacerbation of a disease (ex: pathologic effects)
o Stress can contribute to the development of behaviors that increase the risk of disease (smoking,
overeating, sedentary behavior, alcohol abuse, drug abuse)
o Stressors can be endogenous or exogenous
 Can change internal environment of the body
 Signs and symptoms of change vary from person to person
 General adaptation response helps maintain normal function despite the stressor
 Mild, brief, controllable periods of stress may be perceived as a positive stimuli to
emotional and intellectual growth and development (known as eustress)
o Conditioning factors influence the adaptive capacity of a person
 Internal: genetic predisposition, biologic sex
 External: exposure to environmental agents, life experiences, dietary factors, level of
emotional support
 Relative risk for development of stress-related pathologic process depends on these
conditioning factors
o General Adaptation Syndrome (GAS) – a general systemic reaction to a stressor with physical
manifestations coordinated and dependent upon ech other
 3 stages:
 Alarm stage: occurs when body first experiences stressor
o Generalized stimulation of SNS and hypothalamic-pituitary-adrenal
(HPA) axis leads to the release of catecholamines (norepinephrine and
epinephrine) and cortisol from the adrenal glands
 Resistance stage: body selects most effective and economic stress defense hich
lowers cortisol levels
 Exhaustion stage: if the stressor continues, resources deplete and there will be
systemic damage. This may result in the onset and signs/symptoms of a disease
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Learning Objective 2.
 Describe the stress responses of the neuroendocrine and the immune systems.
Neuorendocrine stress response:
Effects of Stress on immune system
o Decreased immune cell production (cortisol suppresses the inflammatory and immune response)
o Stress decreases thymus activity
 T-cells mature in the thymus
 Changes in T-cell maturation result
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Define allostasis, and explain how it differs from homeostasis.
o Allostasis – the interactive physiologic changes inneuroendocrine, autonomic, and immune
systems that occur in response to real or perceived threats/challenges to homeostasis
 it is the body’s attempt to maintain stability through change
 allostatic load are the changes like immune suppression, activation of the SNS, and
RAAS
 it is the cumulative effects of stress
 can be measured by blood pressure, levels of cortisol/CRP/cholesterol
Relate the sympathetic response to physiologic responses to stress.
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
o Sympathetic nervous system – known as the “fight or flight” response
 it is the rapid response to trauma and emergency that is meant to be a short-term response
 it releases epinephrine and norepinephrine
 these bind tto adrenergic receptors on cells and will increase blood pressure and
heart rate; lower blood flow to skin/guts/kidneys, lower urine production, lower
GI activity
 chronic activation can cause significant harm to the body
Differentiate hormones associated with the stress response and their effects.
o Cortisol – known as the stress hormone
 Helps regulate the stress response by diverting metabolism from building tissues to
supplying energy for dealing with the stress
 Causes the signs and symptoms of chronic stress
 Stress  hypothalamus – secretes cortiotrophin-releasing-hormone (CRH)  anterior
pituitary – secretes adrenocorticotropic hormone (ACTH)  adrenal cortex – secretes
cortisol  alters glucose, fat, and protein metabolism; suppresses inflammatory and
immune responses
 Cortisol increases blood glucose levels, has a stronger sympathetic system effect on the
heart, and decreases nonessential energy-using activities (hormone production, metabolic
rate and reproductive functions, bone formation, RBC/WBC production  what
compromises the immune system
o Aldosterone – released as a result of the Renin-Angiotensin-Aldoseterone System (RAAS)
 RAAS is activated by the SNS or decreased blood flow to the kidneys
 RAAS produces angiotensin II (a strong vasoconstrictor) and stimulates the adrenal
cortex to release aldosterone
 Aldosterone instructs the kidneys to reabsorb sodium (and therefore water) which
increases blood volume and blood pressure
o Antidiuretic Hormone (ADH)
 Released by the posterior pituitary
 Also known as vasopressin
 It causes vasoconstriction
 It increases sympathetic vascular restriction
 Makes kidneys reabsorb water from the urine and brings back to the blood (increases
blood volume)
Learning Objective 3.
 Relate adaptation to homeostasis and stress.
 Adaptation is how we cope with stress (adaptive capacity = coping strategies)
 People have different adaptive capacities
 Adaptation is influenced/determined by physiologic reserve (ability of systems to increase their
level of function), time (fast or slow onset, chronic), genetic endowment, age, sex, health status,
nutrition, sleep-wake cycles, hardiness (personality characteristic – control over
environment/stress), social determinants of health
 List examples of stressors.
 Define adaptation and coping strategies/mechanisms and explain their importance in regard to the
maintenance of homeostasis.
 Adaptation is how we cope with stress (adaptive capacity = coping strategies)
 People have different adaptive capacities
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Adaptation is influenced/determined by physiologic reserve (ability of systems to increase their
level of function), time (fast or slow onset, chronic), genetic endowment, age, sex, health status,
nutrition, sleep-wake cycles, hardiness (personality characteristic – control over
environment/stress), social determinants of health
Contrast anatomic and physiologic reserve; using examples, explain how body systems are able to
increase their function in order to adapt (physiologic reserve) and instances where the body does not
require the use of excesses to survive and maintain homeostasis (anatomic reserve).
 Physiologic reserve: the ability of body systems to increase their function given the need to adapt
 Antomic reserve: Having many body organs, such as lungs, kidneys, and adrenals, are paired to
provide anatomic reserve. Both organs are not needed to ensure the continued existence and
maintenance of the internal environment. Many people function normally withonly one lung or
one kidney
Using examples, discuss the factors that affect an individual’s ability to adapt stress.
 Adaptation is influenced/determined by physiologic reserve (ability of systems to increase their
level of function), time (fast or slow onset, chronic), genetic endowment, age, sex, health status,
nutrition, sleep-wake cycles, hardiness (personality characteristic – control over
environment/stress), social determinants of health
Learning Objective 4.
 Describe the acute stress response in regard to reactions and causes.
o Acute stress response: generally time-limited reactions of the ANS
 Can be detrimental to those with limited coping abilities such as physical or mental
illness, surgery
 Poor self care (sleep, diet) can also lead to worse outcomes
o Chronic stress response: sympathetic activity and cortisol levels are elevated
 Complications often result from reduced immune response
 Is linked to health disorders (cardiovascular disease, GI disease, immune dysfunction,
neurologic dysfunction)
 Is linked to changes in behavioral health (depression, alcoholism, drug abuse, eating
disorders, accidents, suidial ideations)
 Using examples, explain how the acute response to stress might be detrimental.
o Acute stress response is supposed to be a short-term thing
o If it occurs too long there could be physiological damage (i.e. suppressed immune response,
increased BP over longer duration; etc)
o Those with limited coping abilities may not handle acute stress well and physically or mentally
hurt themselves over the stress
 Using examples, discuss the physiologic and psychological effects of chronic illness as a cause of stress.
o Physiologic: impaired body functions
o Psychologic: poor adaptive capacity
 Describe PTSD and differentiate symptoms.
o Post-traumatic stress disorder – chronic activation of the stress response due to a traumatic event
o Triad of symptoms (must be present for at least 1 month)
 Intrusion: “flashbacks”, nightmares, recurrent involuntary stress memories
 Avoidance: emotional numbing that disrupts relationships
 Depression, survivor’s guilt
 Situations that increase stress memories
 Hyperarousal
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
Increased irritability, difficulty concentrating, exaggerated startle reflex, increased
vigilance and concern over safety
o Exaggerated stress response leads to failure to maintain homeostasis
o There is increased SNS activity (increased CRH – corticotropin-releasing hormone) but
DECREASED CORTISOL LEVELS due to a disconnect (no increased release of
adrenocorticotropic hormone (ACTH) as a result of increased CRH