U N I T I
Textbook of Medical Physiology, 11th Edition
GUYTON & HALL
Copyright © 2006 by Elsevier, Inc.
Chapter 1:Functional Organization of the Human Bodyand Control of the “Internal Environment”
Slides by John E. Hall, Ph.D.
Copyright © 2006 by Elsevier, Inc.
Physiology
The science that is concerned with the functionof the living organism and its parts, and of the physical and chemical processes involved.
Copyright © 2006 by Elsevier, Inc.
• The study of disordered body function (i.e. disease)
• The basis for clinical medicine
Pathophysiology
Copyright © 2006 by Elsevier, Inc.
The Human Body - A ComplexSociety of Differentiated Cells
• Cells: the basic structural and functional unit(~ 100 trillion)
• Tissues: (e.g. muscles, epithelial, nervous )
• Organs: (e.g. kidney, heart, liver, pancreas)
• Organ systems: (e.g. cardiovascular, urinary)
Copyright © 2006 by Elsevier, Inc.
Figure 1-2; Guyton & Hall
Exchange Between the Capillaries and Interstitial Fluid
Copyright © 2006 by Elsevier, Inc.
Negative Feedback Control of ArterialPressure Promotes Stability
Art. Pressure SympatheticActivity
Heart RateVasoconstriction
Copyright © 2006 by Elsevier, Inc.
Baroreceptor Reflex : Negative Feedback System - Promotes Stability
Blood vessels, Heart
Baroreceptors
Set-point
Error signal
VasomotorCenters
Sympathetic System
Effectors
BloodPressure
SensorControlled Variable
+
Copyright © 2006 by Elsevier, Inc.
Cardiopulmonary Reflexes:Feed-Forward Control of Blood Pressure –Anticipates a Change
Blood vessels, Heart
Baroreceptors
Error signal
VasomotorCenters
Sympathetic System
Effectors
BloodPressure
SensorControlledVariable
Set-point
Cardiopulmonary Receptors
Cardiopulmonary Pressures
+
Copyright © 2006 by Elsevier, Inc.
Feedback and Feed-Forward Control
• Negative feedback: promotes stability
• Feed-forward: anticipates change
• Positive feedback: promotes a change in one direction, often leading to
instability, disease, and sometimes death.
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