review4 - 1 Review for test#4 39 Life is a series of...

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Unformatted text preview: 6/11/11 1 Review for test #4 39 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 This review only include the new material for the fourth test (all animal health and production related lectures). It highlights the main topics having in mind the test questions you will see on Wednesday. Remember all tests are cumulative. Make sure you answer your teaching evaluations on-line It is thought that circadian regulation of physiology and behavior imparts survival advantages to organisms that use clocks. In mammals, a master clock resident in the SCN synchronizes other central and peripheral oscillators to evoke this regulation. This master oscillator consists of interlocking transcriptional- translational feedback loops, and it regulates both core clock genes necessary for oscillator maintenance as well as speci f c output genes that directly or indirectly mediate physiology under circadian control. It is now clear that both neuroanatomic and molecular outputs of the clock are necessary for proper circadian clock function ( Panda S and Hogenesch JB, 2004) . Biological Clocks 6/11/11 2 ¡ S E sensor integration center (concept vs anatomy) effector afferent “story line” efferent “story line” negative feedback “story line” e.g. t°C/F Biological Clocks or what if … “anticipation” A B C D feedback feedforward S ¡ E Theoretically, a feedforward mechanism anticipates the logistics needed to carry on a specific physiological effect Biological Clocks Keep this thought in mind for the rest of this lecture. 6/11/11 3 Biological Clocks Evening (E) / morning (M) oscillators in mammalian photoperiodism. A, oscillators entrained to a short night rhythm B, as nights get longer (PRC) the oscillators drift apart since their free running rhythms differ C, in long nights oscillators adopt an entrainment pattern where they overlap minimally A B C entrainment (zeitgebers) one clock vs. two clocks entrainment vs. resetting Its all in the timing 6/11/11 4 Its all in the timing SCN Its all in the timing 6/11/11 5 HPA axis and its “story lines” Stress HPA axis and its “story lines” Stress and the HPA Axis Stress pushes the homeostatic envelope to a point from which the system might recover, or to the starting point of system pathologies 6/11/11 6 HPA axis and its “story lines” Stress and the HPA Axis Insulin-induced hypoglycemia, an example of homeostatic events set in motion in response to a stressor, to maintain system steady state Stress and Immunity The neuroendocrine - immune connection has driven a reversal of reductionist approaches acute vs chronic stress IL-1 brain ventricle injection HPA axis and its “story lines” Involvement of the PVN is a characteristic of the homeostatic response to stressors such as the hypoglicemic and other tests 6/11/11...
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review4 - 1 Review for test#4 39 Life is a series of...

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