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lec 20 StressImmuneProduction

lec 20 StressImmuneProduction - Stress Immunity and the HPA...

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6/11/11 1 Stress, Immunity and the HPA axis 31 The goal of these lectures is to discuss basic physiology associated with the control of stress and immunity. This lecture together with the previous one (biological rhythms) are an introduction to the last part of the course. The sections for this lecture are: Stress and the HPA axis Stress an Immunity Chronic Stress Models Autoimmune Diseases Life is a series of chemical reactions occurring in compartmentalized environments. The main purpose of life is to keep itself alive Physiology, the study of how life works, is based on the simultaneous occurrence of the following three concepts: levels of organization structure / function relationship homeostatic regulation What is stress ??? How many definitions of stress do you know ??? How many different stress types do exist ??? Is there a common denominator for stress ??? Why we call the HPA axis, the stress axis ??? Acute and chronic stress responses ??? What does stress have to do with production ??? Stress and the HPA Axis HPA axis and its “story lines”
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6/11/11 2 When threat-related information reaches the brain two different response are generated: 1) The brain automatically engages THE AMIGDALA, an emergency fear center. This sent emergency information to other parts of the brain mediating the stress response (Epi, sweat, rapid heart beat, increased blood pressure). 2) The brain engages the THALAMUS first and then the CORTEX. The latter analyzes the information and decides whether or not a stress response is required. If the threat is not real or the response triggered by the amigdala is excessive, prefrontal cortex inhibits the amigdala. If the threat is real the cortex support it and the body stays on alert. Stress and the HPA Axis HPA axis and its “story lines” Stress pushes the homeostatic envelope to a point from which the system might recover, or to the starting point of system pathologies The amygdala provokes a series of changes in the brain’s chemicals that puts the entire body in a stress mode. The amigdala does not check for accuracy of the threat. Another part of the stress signal goes to the cortex, the thinking part, to figure out what is going on. Then the information goes to the prefrontal cortex, and from here the amygdale receives a very clear message to relax.
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