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STRESS

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

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  1. STRESS

  2. What is stress?

  3. Physical stressors • Illness • Surgery • Cold • Heat • Hunger • Competitive athletics • Fighting • Fleeing

  4. 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

  5. Fight or run away? image from: naturescrusaders.wordpress.com

  6. Dominance versus submission image at: www.flickr.com/photos/chrisgcom/2245593489

  7. Stress and performance in competitive sports image at: www.transfersnowboard.com/features/7343011

  8. 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

  9. Stress Hypothalamus Sympathetic nervous system CRH Epinephrine/norepinephrine ACTH cortisol

  10. Location of adrenal glands image at: www.aurorahealthcare.org/yourhealth/healthgat

  11. 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

  12. Context matters

  13. Psychological stress: exams image at: www.engineering.unl.edu/.../Summer07/05.shtml

  14. 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

  15. Diurnal variations in plasma cortisol http://junior.britannica.com/eb/art/print?id=1588&articleTypeId=1

  16. growth of adrenal cortex

  17. 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

  18. 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

  19. 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

  20. Some conditions in which corticosteroids are useful • Allergic disorders (asthma, atopic dermatitis) • Gastrointestinal disorders (Crohn’s disease, ulcerative colitis) • Arthritis • Skin irritations

  21. 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-...

  22. growth of adrenal cortex

  23. Differences between physical and psychological stressors

  24. 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

  25. Psychological stress increases susceptibility to the common cold From: Cohen SC et al, New England Journal of Medicine 325:606-612, 1991

  26. 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

  27. Stress promotes type II diabetes From: Mooy J et al, Diabetes Care, 23:1443, 2005

  28. 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

  29. 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

  30. 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

  31. Weighing risk versus reward while experiencing a stressor Image at: www.canada.com/.../1186256/story.html

  32. Balloon analogue risk task the image at: psycnet.apa.org/index.cfm?fa=fulltext.printAr...

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

  34. Males Stress→  testosterone Females Stress→  oxytocin

  35. 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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