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
Fight or run away?
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Dominance versus submission
Stress and performance in competitive sports
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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
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Location of adrenal glands
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
Psychological stress: exams
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The Limbic System
Site where emotional stimuli, is integrated, and behavioral and physiologic responses are initiated
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Diurnal variations in plasma cortisol
http://junior.britannica.com/eb/art/print?id=1588&articleTypeId=1
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 diversestimuli, including psychological 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
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 diversestimuli, including psychological stress
Some conditions in which corticosteroids are useful
• Allergic disorders (asthma, atopic dermatitis)
• Gastrointestinal disorders (Crohn’s disease, ulcerative colitis)
• Arthritis
• Skin irritations
Typical course of prednisone treatment (oral corticosteroid)
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Why is it necessary to “taper off”
Day 6Day 5Day 4Day 3Day 2Day 1
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: HypertensionAtherosclerosisSudden cardiac death
From: Cohen SC et al, New England Journal of Medicine 325:606-612, 1991
Psychological stress increases susceptibility to the common cold
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: HypertensionAtherosclerosisSudden cardiac death
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: HypertensionAtherosclerosisSudden cardiac death
Leor, J. et al. N Engl J Med 1996;334:413-419
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
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
US National Mortality Data from 1973 to 1998
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Weighing risk versus reward while experiencing a stressor
Balloon analogue risk task
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