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STRESS. What is stress?. Physical stressors Illness Surgery Cold Heat Hunger Competitive athletics Fighting Fleeing . Psychological stressors Any new experience (potentially) Anticipation of something previously experienced as unpleasant

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Stress

STRESS


Stress

What is stress?


Stress

  • Physical stressors

  • Illness

  • Surgery

  • Cold

  • Heat

  • Hunger

  • Competitive athletics

  • Fighting

  • Fleeing


Stress

  • Psychological stressors

  • Any new experience (potentially)

  • Anticipation of something previously experienced as unpleasant

  • Situations in which rules are changed or previous behavior no

  • longer effective

  • Fighting or observing others fighting

  • Crowding

  • Acute situations: airplane flight, exam, new situations,

  • competitive athletics, workdays vs weekends

  • Chronic life situations (divorce, death in the family, illness in the family)

  • Note: Context matters


Stress

Fight or run away?

image from: naturescrusaders.wordpress.com


Stress

Dominance versus submission

image at: www.flickr.com/photos/chrisgcom/2245593489


Stress

Stress and performance in competitive sports

image at: www.transfersnowboard.com/features/7343011


Stress

  • Physiological responses to stress

  • Increased rate and contractility of the heart

  • Alterations in blood flow distribution

  • Increased gluconeogenesis (synthesis of glucose)

  • Mobilization of amino acids (used to synthesize glucose)

  • Increased muscle contractility and decreased fatiguability

  • Increased learning and memory


Stress

Stress

Hypothalamus

Sympathetic nervous system CRH

Epinephrine/norepinephrine ACTH

cortisol


Stress

Location of adrenal glands

image at: www.aurorahealthcare.org/yourhealth/healthgat


Stress

  • Effects of epinephrine

  • Increased heart rate and contractility

  • Effects on arteriolar smooth muscle

  • Widens pupil and flattens lens (far vision)

  • Decreases GI motility

  • Promotes glucose synthesis

  • Increases central nervous system activity

  • Decreases fatigue of skeletal muscle


Stress

Context matters


Stress

Psychological stress: exams

image at: www.engineering.unl.edu/.../Summer07/05.shtml


Stress

The Limbic SystemSite where emotional stimuli, is integrated, and behavioral and physiologic responses are initiated

http://cwx.prenhall.com/bookbind/pubbooks/morris5/medialib/images/F02_09.jpg


Stress

Diurnal variations in plasma cortisol

http://junior.britannica.com/eb/art/print?id=1588&articleTypeId=1


Stress

growth of

adrenal cortex


Stress

  • Hans Selye: General Adaptation Response

  • Chronic exposure of rats to noxious stimuli (cold, restraint, surgery):

    • Enlarged adrenal glands

    • Atrophy of lymphoid structures

    • Gastric ulcers and bleeding

Note: similar responses were observed with many diverse

stimuli, including psychological stress


Stress

  • Effects of cortisol

  • Increased plasma glucose

  • Increased contractility of skeletal and cardiac muscle

  • Inhibits bone growth

  • Inhibits protein synthesis, accelerates protein degradation

  • -inhibits collagen formation, easy bruising

  • Required for maintenance of blood pressure

  • CNS effects on learning and other responses

  • Increases gastric secretions

  • Modulates inflammatory and immune responses


Stress

  • Hans Selye: General Adaptation Response

  • Chronic exposure of rats to noxious stimuli (cold, restraint, surgery):

    • Enlarged adrenal glands

    • Atrophy of lymphoid structures

    • Gastric ulcers and bleeding

Note: similar responses were observed with many diverse

stimuli, including psychological stress


Stress

  • Some conditions in which corticosteroids are useful

  • Allergic disorders (asthma, atopic dermatitis)

  • Gastrointestinal disorders (Crohn’s disease, ulcerative colitis)

  • Arthritis

  • Skin irritations


Stress

Typical course of prednisone treatment (oral corticosteroid)

Why is it necessary to “taper off”

Day 6

Day 5

Day 4

Day 3

Day 2

Day 1

image at: www.healthcentral.com/asthma/h/how-long-does-...


Stress

growth of

adrenal cortex


Stress

Differences between physical and psychological stressors


Stress

  • Effects of chronic stress

  • GI system: worsens ulcers

  • Immune system: immunosuppression (increased autoimmune

  • diseases, increased infections)

  • Endocrine system: type II diabetes

  • Growth: retards growth in children, induces weight and bone

  • loss in adults

  • Cardiovascular system:

    • Hypertension

    • Atherosclerosis

    • Sudden cardiac death


Stress

Psychological stress increases susceptibility to the common cold

From: Cohen SC et al, New England Journal of Medicine 325:606-612, 1991


Stress

  • Effects of chronic stress

  • GI system: worsens ulcers

  • Immune system: immunosuppression (increased autoimmune

  • diseases, increased infections)

  • Endocrine system: type II diabetes

  • Growth: retards growth in children, induces weight and bone

  • loss in adults

  • Cardiovascular system:

    • Hypertension

    • Atherosclerosis

    • Sudden cardiac death


Stress

Stress promotes type II diabetes

From: Mooy J et al, Diabetes Care, 23:1443, 2005


Stress

  • Effects of chronic stress

  • GI system: worsens ulcers

  • Immune system: immunosuppression (increased autoimmune

  • diseases, increased infections)

  • Endocrine system: type II diabetes

  • Growth: retards growth in children, induces weight and bone

  • loss in adults

  • Cardiovascular system:

    • Hypertension

    • Atherosclerosis

    • Sudden cardiac death


Stress

Daily numbers of Deaths Listed by the Department of Coroner of Los Angeles County from January 10 through 23, 1991, 1992, 1993, and 1994

Emotional stress can trigger cardiac events in at risk individuals: Earthquake occurred early in the morning of Jan 17, 1994 in Los Angeles

Leor, J. et al. N Engl J Med 1996;334:413-419


Stress

US National Mortality Data

from 1973 to 1998

From: BMJ 2001;323:1443-1446

The number “4” and the word

“death” are pronounced similarly

in Chinese and Japanese and “4”

is considered to be unlucky


Stress

Weighing risk versus reward while experiencing a stressor

Image at: www.canada.com/.../1186256/story.html


Stress

Balloon analogue risk task

the image at: psycnet.apa.org/index.cfm?fa=fulltext.printAr...


Stress

Lighthall N, et al PLoS One, Volume 4, issue 7, 2009


Stress

Males

Stress→  testosterone

Females

Stress→  oxytocin


Stress

Stress

  • heart rate

  • cortisol

Control treatment

Block oxytocin receptors in the brain

Stress

  •  heart rate

  •   cortisol

Conclusion: Oxytocin reduces the cardiovascular responses to stress

Wysol, A et al, J Physiol Pharmacol, 59(Suppl 5):117-132, 2008


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