CHAPTER 9STRESS AND ADAPTATION
Essentials of Pathophysiology
PRE LECTURE QUIZ (TRUE/FALSE)
The sympathetic nervous system manifestation of the stress reaction has been called the fight-or-flight response.
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.
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PRE LECTURE QUIZHardine
ss
Hormones
Intrusion
Physiologic
Stressors
•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.
•According to Hans Selye, the events or environmental agents responsible for initiating the stress response are called _________________.
•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
stressorschange the internal
environment of part of the body
general adaptation response helps maintain normal function in spite
of the stressor
signs and symptoms
of the change
signs and symptoms of the
general adaptation response
CORTISOL — THE “STRESS HORMONE”
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
CRH
ACTH
Hypothalamus
Anterior pituitary
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 production
º 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
d. 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.
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
hypothalamus
SNS neurons
adrenal medulla
Pain, fear, low BP
SNS activated
Norepinephrine
Epinephrine released into blood
Blood pressure increased
Blood flow to skin, guts, and kidneys reduced
Skin becomes pale
Urine production decreases
GI activity decreases
epinephrine and norepinephrine
heart
increased HRincreased heart
strength
increased BP
blood vessels
vasoconstriction in skin, guts,
kidneys
SYMPATHETIC SYSTEM “FIGHT-OR-FLIGHT”RESPONSE
RENIN-ANGIOTENSIN-ALDOSTERONE PATHWAY
Activated by: Sympathetic
system Decreased blood
flow to kidneys Angiotensin I:
weak vasoconstriction
Angiotensin-converting enzyme (ACE)
Angiotensin II: stronger vasoconstriction
ACE
Kidneys release renin
Angiotensin I
Angiotensin II
RENIN-ANGIOTENSIN-ALDOSTERONE PATHWAY (CONT.)
Angiotensin II: stronger vasoconstriction
Also stimulates the adrenal cortex
Aldosterone released
adrenal cortex
Angiotensin II
Aldosterone
QUESTION
True or False:Angiotensin-converting enzyme must be
present in order for aldosterone to be released by the adrenal gland.
ANSWER
TrueWithout 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
Na+/K+ ATPase in nephrons activated Kidneys reabsorb
Na+ and water Kidneys secrete
K+
kidneys
aldosterone
reabsorb Na+ and water
increased blood volumeoliguria
secrete K+
= Very low urine output
stressorschange the internal
environment of part of the body
general adaptation response helps maintain normal function in spite
of the stressor
signs and symptoms
of the change
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 glucoseQuestion: What should be fixed first? Why?
releases
which affect
release
which affect
Central Nervous System
hormones and neurotransmitters
immune cells
inflammatory mediators
STRESS “SNOWBALL” / POSITIVE FEEDBACK
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
d. All of the aboveStress 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.
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 shotQuestion: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?