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CHAPTER 9 STRESS AND ADAPTATION Essentials of Pathophysiology.

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Presentation on theme: "CHAPTER 9 STRESS AND ADAPTATION Essentials of Pathophysiology."— Presentation transcript:

1 CHAPTER 9 STRESS AND ADAPTATION Essentials of Pathophysiology

2 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. T T F T T

3 PRE LECTURE QUIZ Hardiness 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.

4 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

5 ALLOSTASIS  A difference between the perceived situation and desired situation causes the person to take action  Cognitive activation theory of stress

6 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

7 stressors change 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

8 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

9 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

10 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.

11 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.

12 ANTIDIURETIC HORMONE (ADH)  Also called vasopressin  Causes vasoconstriction  Makes kidneys reabsorb water from urine to blood

13 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

14  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 HR increased heart strength increased BP blood vessels vasoconstriction in skin, guts, kidneys SYMPATHETIC SYSTEM “FIGHT-OR-FLIGHT” RESPONSE

15 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

16 RENIN-ANGIOTENSIN-ALDOSTERONE PATHWAY (CONT.)  Angiotensin II: stronger vasoconstriction  Also stimulates the adrenal cortex  Aldosterone released adrenal cortex Angiotensin II Aldosterone

17 QUESTION True or False: Angiotensin-converting enzyme must be present in order for aldosterone to be released by the adrenal gland.

18 ANSWER True Without angiotensin-converting enzyme, angiotensin II would not be created. Angiotensin II stimulates the adrenal cortex to produce aldosterone.

19 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 volume oliguria secrete K+ = Very low urine output

20 stressors change 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

21 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?

22 releases which affect release which affect Central Nervous System hormones and neurotransmitters immune cells inflammatory mediators STRESS “SNOWBALL” / POSITIVE FEEDBACK

23 EFFECTS OF STRESS ON THE IMMUNE SYSTEM  Decreased immune cell production  Decreased thymus activity  Changes in the kind of immune cells produced

24 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

25 ANSWER d. 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.

26 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

27 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?

28 ACUTE STRESS Question:  Which organs of the body would you expect to see damaged by acute stress? Why?

29 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

30 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?

31 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?

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