STRESS

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

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

14. 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

15. Context matters

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

18. 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

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

22. growth of adrenal cortex

23. 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

24. 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

25. 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

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

27. 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-...

28. growth of adrenal cortex

29. Differences between physical and psychological stressors

30. 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

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

32. 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

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

34. 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

35. 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

36. 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

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

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

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

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

41. 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