412g Dr Park-Sarge lecture notes-1 2009

412g Dr Park-Sarge lecture notes-1 2009 - Overview and...

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1 Overview and Basic Concepts in Physiology O.K. Park-Sarge, Ph.D. MN502-A, UKMC, okps@uky.edu Outlines: Outlines: I. Introduction and Homeostasis II. Cells and Tissues III. Molecular Movement via Cell Membrane V. Communication and Signaling Acknowledgements Acknowledgements: Figures and pictures are from the following: Widmaier et al (2008) Vander’s Human Physiology 11 th ed, Mc Grow Hill press Silverthorn (2004) Human Physiology, Pearson-Benjamin Cunning Press Introduction and Homeostasis, pp1-17 Physiology is the study of living things/body function. Study ‘why’ ( function ): ‘how’ (processes; mechanisms ): where/what (anatomy). Physiology deals with maintenance of internal stability/homeostasis . Maintain physiological variables at se poin values at the cell tissue Maintain physiological variables at set-point values at the cell, tissue, organ, system, and whole-body level. Set-point: averaged mean over time. What if a physiological variable deviates from its “set-point”? Receives an error signal and launches correction commands to restore the homeostasis (=internal stability). Body function is regulated in a need , not desire, basis.
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2 Equilibrium Is homeostasis same as equilibrium? Homeostasis E Energy is used to maintain homeostasis . e.g., A human cell maintains intracellular (~120 mM) vs. extracellular (~10 mM) concentration of K+ by continuously pumping K+ ion at the expense of energy using Na-K ATPase. What would happen to the K+ concentration gradient in a person with defective Na-K-ATPases? stimulate The body maintains homeostasis by using the “check and balance” principle of the __________ feedback loop. inhibit homeostatic, typical body response, negative feedback non-homeostatic, explosive, rare positive feedback The nervous and endocrine systems mediate the body’s check and balance to maintain homeostasis.
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3 Figure 1-7 A reflex arc is a typical example of neural homeostatic control in which the receptor is a sensory neuron, the integrating center the brain or spinal cord, and the effector a muscle. A receptor (sensor) – afferent pathway - an integrating center – efferent pathway – effector. Integrating Center Receptor = Sensor Effector Away from the set-point = Stimulus Negative Feedback Mechanism The endocrine homeostatic control involves the gland serving as both the sensor and the integrating center. Figure 1-3 Blood glucose levels Figure 11-11 Increased glucose levels in the pancreas directly stimulate secretion of insulin. “Insulin targets” are cells that have insulin-receptors. increase after eating. Levels return to their set point via homeostasis. This is an example of dynamic constancy. Levels change over short periods of time, but remain relatively constant over long periods of time.
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4 Is a set-point for a physiological variable fixed?
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412g Dr Park-Sarge lecture notes-1 2009 - Overview and...

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