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Essentials of Pathophysiology
CHAPTER 9
STRESS AND ADAPTATION
PRE LECTURE QUIZ (TRUE/FALSE)
T

The sympathetic nervous system manifestation of the stress
reaction has been called the fight-or-flight response.
T

F

T

T

According to Walter B. Cannon, allostasis is achieved through a
system of carefully coordinated physiologic processes that
oppose change, not the ability to achieve stability through
change.
The alarm stage is the third stage of the general adaptation
syndrome (GAS).
The stress response is strongly influenced by both the nervous
and the endocrine systems.
Nutrition, physiologic reserve, psychosocial factors, and sleep–
wake cycles are known to affect a person’s appraisal of a
stressor and the coping mechanisms used to adapt to the new
situation.
PRE LECTURE QUIZ
Hardiness
Hormones
•With regard to post-traumatic stress disorder (PTSD), the
______________ state refers to the reexperiencing of an event
through the occurrence of “flashbacks” during waking hours or
nightmares in which the past traumatic event is relived.
Intrusion
•According to Hans Selye, the events or environmental agents
responsible for initiating the stress response are called
Physiologic _________________.
Stressors
•There are a number of ________________ that are released
from the hypothalamus, anterior pituitary, and adrenal cortex in
response to stress.
•__________________ describes a personality characteristic
that includes having a purpose in life and the ability to
conceptualize stressors as a challenge, rather than a threat.
•The ability of body systems to increase their function given the
need to adapt is known as _________________ reserve.
HOMEOSTASIS
The body requires that a level of homeostasis
or constancy be maintained during changes
in internal and external environments.
 Give an example in which your body kept
some aspect of its internal environment
stable. Aspects you might consider include:

 Water
balance
 Weight
 Blood glucose
 Temperature
ALLOSTASIS

A difference between the perceived situation and
desired situation causes the person to take action

Cognitive activation theory of stress
GENERAL ADAPTATION SYNDROME (GAS)

Also called generalized stress response
 Corticotropin-releasing hormone (CRH) production
 Antidiuretic hormone release
 Sympathetic nervous system (SNS) activation
 Renin-angiotensin-aldosterone pathway activation
stressors
change the internal
environment of part of
the body
signs and
symptoms
of the
change
general adaptation
response helps maintain
normal function in spite
of the stressor
signs and
symptoms of the
general adaptation
response
CORTISOL — THE “STRESS HORMONE”
Hypothalamus
CRH



Helps regulate the
stress response
Diverts metabolism
from building tissues
to supplying energy
for dealing with the
stress
Causes signs and
symptoms of chronic
stress
Anterior pituitary
ACTH
Adrenal cortex
Cortisol
Alters glucose,
fat, and protein
metabolism
Suppresses
inflammatory and
immune responses
CORTISOL RELEASE
Increases blood glucose
 Stronger sympathetic system effect on heart
rate
 Decreases nonessential energy-using
activities like:

 Hormone
º
production
Metabolic rate and reproductive functions decrease
 Bone
formation
 Red and white blood cell production
º
Immune system becomes depressed
QUESTION
Why does cortisol production result in increased
blood glucose levels?
a. Glucose leads to a strong sympathetic nervous
system response.
b. Glucose stimulates RBC production.
c. Glucose stimulates release of adrenaline.
d. Glucose provides energy.
ANSWER
Glucose provides energy.
The body’s energy requirements increase during
periods of stress. Cortisol is the “stress
hormone” – one of the effects of cortisol
release is increased blood glucose levels.
Glucose helps to meet the body’s increased
demand for energy.
d.
ANTIDIURETIC HORMONE (ADH)



Also called vasopressin
Causes vasoconstriction
Makes kidneys reabsorb water from urine to
blood
SYMPATHETIC SYSTEM “FIGHT-OR-FLIGHT”
RESPONSE
Rapid response to
trauma and
emergency
 Epinephrine
(adrenalin) and
norepinephrine
(noradrenalin) both
released
 Both attach to
adrenergic receptors
on cells

Pain, fear, low BP
hypothalamus
SNS activated
SNS neurons
Norepinephrine
adrenal
medulla
Epinephrine released
into blood
SYMPATHETIC SYSTEM “FIGHT-OR-FLIGHT”
RESPONSE
Blood pressure
increased
 Blood flow to
skin, guts, and
kidneys reduced
 Skin becomes
pale
 Urine production
decreases
 GI activity
decreases

epinephrine and
norepinephrine
blood
vessels
heart
increased HR
increased heart
strength
vasoconstriction
in skin, guts,
kidneys
increased
BP
RENIN-ANGIOTENSIN-ALDOSTERONE
PATHWAY
Kidneys release renin
Angiotensin I
ACE
Angiotensin II

Activated by:
 Sympathetic
system
 Decreased blood
flow to kidneys
Angiotensin I: weak
vasoconstriction
 Angiotensinconverting enzyme
(ACE)
 Angiotensin II:
stronger
vasoconstriction

RENIN-ANGIOTENSIN-ALDOSTERONE PATHWAY
(CONT.)
Angiotensin II:
stronger
vasoconstriction
 Also stimulates the
adrenal cortex
 Aldosterone released

Angiotensin II
adrenal
cortex
Aldosterone
QUESTION
True or False:
Angiotensin-converting enzyme must be present
in order for aldosterone to be released by the
adrenal gland.
ANSWER
True
Without angiotensin-converting enzyme,
angiotensin II would not be created.
Angiotensin II stimulates the adrenal cortex to
produce aldosterone.
RENIN-ANGIOTENSIN-ALDOSTERONE
PATHWAY (CONT.)
Aldosterone
released
kidneys
 Na+/K+ ATPase in
nephrons
reabsorb Na+
secrete K+ activated
and water
 Kidneys reabsorb
aldosterone
increased blood volume
oliguria

Na+ and water
 Kidneys secrete K+
= Very low urine output
stressors
change the internal
environment of part of
the body
signs and
symptoms
of the
change
general adaptation
response helps maintain
normal function in spite
of the stressor
signs and
symptoms of the
general adaptation
response
SCENARIO:
After an accident, a patient has the following:
 Increased heart rate
 No urine production
 No bowel sounds
 Pale, sweaty skin
 Low blood pressure
 Dilated pupils
 Elevated blood glucose
Question:
 What should be fixed first? Why?
STRESS “SNOWBALL” / POSITIVE FEEDBACK
which
affect
Central
Nervous
System
releases
inflammatory
mediators
hormones and
neurotransmitters
which
affect
release
immune
cells
EFFECTS OF STRESS ON THE IMMUNE SYSTEM



Decreased immune cell production
Decreased thymus activity
Changes in the kind of immune cells produced
QUESTION
How does stress affect your immune system?
a. The thymus atrophies.
b. Fewer lymphocytes are produced.
c. Inflammatory mediators are released.
d. All of the above
ANSWER
All of the above
Stress causes the immune system to be
suppressed. The thymus gland atrophies
(shrinks), so that fewer T-lymphocytes are
produced. Monocytes and lymphocytes cross
the blood-brain barrier and release
inflammatory mediators and cytokines.
d.
PHYSIOLOGIC STRESS




Stress-induced changes in body functions
Detected by body’s normal regulatory sensors
The body alters function to restore normal balance
When normal balance is restored, negative feedback
stops the reaction
PSYCHOSOCIAL STRESS
Directly affects the central nervous system
 Turns on the stress responses, even when the body’s
internal sensors have not detected an imbalance
Question:
 Do the stress responses solve the person’s problem?
 Will negative feedback tell them when to turn off?

ACUTE STRESS
Question:
 Which organs of the body would you expect to see
damaged by acute stress? Why?
RESULTS OF LONG-TERM STRESS


Chronic stress
 Sympathetic activity and cortisol are elevated
 Complications result from the reduced immune
response
Posttraumatic stress disorder
 Sympathetic system is activated
 Cortisol levels are decreased
SCENARIO:
Mr. P saw violent combat in the army but he dealt with it and
has become a successful air traffic controller.
 He is 50 and overweight:
 With increased blood pressure and occasional
tachycardia
 Insomnia
 GI discomfort
– He has had several colds already this year, and
wants a flu shot
Question:
What about his case might be stress-related?
SCENARIO (CONT.):
The doctor has recommended relaxation therapy
 Mr. P is furious about this “new age gobbledygook”
Question:
 How will you explain its physiologic basis to him?