UNIT I
Textbook of Medical Physiology, 11th Edition
Chapter 1:
Functional Organization of the Human Body
and Control of the “Internal Environment”
Slides by John E. Hall, Ph.D.
GUYTON & HALL
Copyright © 2006 by Elsevier, Inc.
Physiology
The science that is concerned with the function
of the living organism and its parts, and of
the physical and chemical processes involved.
Copyright © 2006 by Elsevier, Inc.
Pathophysiology
• The study of disordered body
function (i.e. disease)
• The basis for clinical medicine
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Anatomy
The study of the structure of the body.
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The Human Body - A Complex
Society 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)
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Exchange Between the Capillaries
and Interstitial Fluid
Figure 1-2; Guyton & Hall
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Negative Feedback Control of Arterial
Pressure Promotes Stability
Art. Pressure
Sympathetic
Activity
Heart Rate
Vasoconstriction
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Baroreceptor Reflex :
Negative Feedback System - Promotes Stability
Set-point
Error signal
+
Vasomotor
Centers
Sympathetic
System
Effectors
Blood vessels,
Heart
Sensor
Controlled
Variable
Baroreceptors
Blood
Pressure
Copyright © 2006 by Elsevier, Inc.
Cardiopulmonary Reflexes:
Feed-Forward Control of Blood Pressure –
Anticipates a Change
Cardiopulmonary
Receptors
Set-point
+
Error signal
Sympathetic
System
Vasomotor
Centers
Cardiopulmonary
Pressures
Effectors
Blood vessels,
Heart
Sensor
Controlled
Variable
Baroreceptors
Blood
Pressure
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.
Copyright © 2006 by Elsevier, Inc.
Positive Feedback of Hemorrhagic Shock
Figure 1-3;
Guyton & Hall
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Hemorrhagic Shock:
Positive Feedback
Severe Hemorrhage
+
Venous Return
Cardiac Output
Blood Pressure
Coronary Blood Flow
Cardiac Contractility
Copyright © 2006 by Elsevier, Inc.