NURS 1017 Unit 10 Stress and Disease PDF

NURS 1017 Pathophysiology 1 Unit 10 Stress and Disease Avinash Thadani, PhD HBSN  Today’s Lesson 1. Homeostasis vs. Allostasis vs. Allostatic load vs. Allostatic overload 2. Stressors 3....

NURS 1017 Pathophysiology 1 Unit 10 Stress and Disease Avinash Thadani, PhD HBSN  Today’s Lesson 1. Homeostasis vs. Allostasis vs. Allostatic load vs. Allostatic overload 2. Stressors 3. Physiological and pathophysiological effects of acute and chronic stress 4. The General Adaptation Syndrome 5. Review the neural and hormonal mediators of stress 6. Adaptation, coping, and illness Readings: Chapter 2 (while referring to the learning outcomes in the syllabus) 2  Stress Physical, emotional, or chemical event(s) that cause tension in our body or mind Actual feelings produced by this tension A threat (direct, indirect, sensed or unconsciously sensed) to the homeostasis of the individual How we perceive the significance of the stressor has impact on our ability to cope with or adapt to this stressor 3  Stressors Anything that challenges our state of homeostasis  require allostatic mechanisms to kick in Can be external or internal Can be psychosocial (HPA axis responds mainly to psychosocial stressors when sense of self is threatened) Key is to prevent hypothalamic stimulation, especially with psychosocial events that triggers HPA events 4 The Stress Response and Development of Allostatic Load McEwen BS. N Engl J Med 1998;338:171-179. 5  Hans Selye Found that 3 physiological events always occur with stimulus/stressor (all are nonspecific responses irrespective of cause): 1. Adrenal cortex enlarges 2. Thymus, spleen, and lymph nodes shrink 3. Bleeding ulcers develop in stomach & duodenum General Adaptation Syndrome (GAS) When homeostasis disrupted by psychological or environmental demands Allostatic mechanisms in place to return to homeostasis 6  Stages of General Adaptation Syndrome Alarm Stage Hypothalamus senses stimulus & starts GAS via activation of sympathetic nervous system  secretion of glucocorticoids & responses  sympathetic nervous system activity  secretion of epinephrine (from adrenal medulla) Fight-or-flight manifestations  resistance to stressors Once pituitary gland activated, the alarm stage can’t be turned off; have to reach resistance stage 7  Stages of General Adaptation Syndrome Resistance Stage Sympathetic nervous system & adrenal gland are fully activated Once stressor(s) are dealt with, all mechanisms return to normal: Normal glucocorticoid secretion Normal sympathetic nervous system activity Normal epinephrine secretion (adrenal medulla) Resolution of fight-or-flight manifestations  resistance (adaptation) to stressor 8  Stages of General Adaptation Syndrome Exhaustion Stage Occurs when body can’t return to homeostasis; all body resources have been utilized  glucocorticoid secretion followed by significant  in secretion 3 stress findings  (i) hypertrophied adrenal glands; (ii) atrophied thymus & lymph nodes; (iii) bleeding ulcers (stomach & duodenum) Loss of resistance to stressor; death of organism possible 9 Alarm Stage GAS (Hypothalamic-Pituitary-Adrenal (HPA) Axis Figure 02-01. Steps of Selye’s alarm stage of the general adaptation syndrome. 10 Neuroendocrine Response to Stressors Figure 02-02. Neuroendocrine interactions in response to a stressor. Receptors are excited by stressful stimuli and relay the information to the hypothalamus. The hypothalamus signals the adrenal cortex (by way of the anterior pituitary) and the sympathetic pathways (by way of the autonomic nervous system). The stress response is then mediated by the catecholamines (i.e., epinephrine and norepinephrine) and by the glucocorticoids (predominantly cortisol). 11  Neurohormonal Mediators of Stress and Adaptation 1. Catecholamines: norepinephrine and epinephrine Play an integral role in allostasis Sympathico-adrenal system response mediates the flight-or-fight response 2. Adrenocortical steroids: cortisol and aldosterone Critical to maintenance of homeostasis May synergize or antagonize effects of catecholamines 12  Neurohormonal Mediators of Stress and Adaptation 3. Endorphins and enkephalins: endogenous opioids (body’s natural pain relievers) Raise pain threshold; produce sedation and euphoria 4. Immune cytokines (e.g., interleukin-1): secreted by macrophages during stress response, thus enhancing immune system response 13  Adaptation, Coping, and Illness Individual stress responses: change with time and circumstances Adaptation: biopsychosocial process of change in response to new or altered circumstances, internal or external in origin Coping: behavioral adaptive response to a stressor using culturally based coping mechanisms Adaptation and coping: terms often used interchangeably 14 Factors Affecting the Ability to Adapt 15 Effects of Allostatic Overload on the Body Figure 02-03. Effects of allostatic overload on body organs and systems. 16  Summary Allostasis, Allostatic load, Allostatic overload GAS Stress response (HPA axis) Stress hormones (catecholamines and cortisol) Adaptation 17  Next Lesson Unit 11 (The Endocrine Disorders) 18