UNIT I Textbook of Medical Physiology 11 th

UNIT I Textbook of Medical Physiology, 11 th 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 Copyright © 2006 by Elsevier, Inc.

Anatomy The study of the structure of the body. Copyright © 2006 by Elsevier, Inc.

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) Copyright © 2006 by Elsevier, Inc.

Exchange Between the Capillaries and Interstitial Fluid Figure 1 -2; Guyton & Hall Copyright © 2006 by Elsevier, Inc.

Negative Feedback Control of Arterial Pressure Promotes Stability Art. Pressure Sympathetic Activity Heart Rate Vasoconstriction Copyright © 2006 by Elsevier, Inc.

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 Copyright © 2006 by Elsevier, Inc.

Hemorrhagic Shock: Positive Feedback Severe Hemorrhage + Venous Return Cardiac Output Blood Pressure Coronary Blood Flow Cardiac Contractility Copyright © 2006 by Elsevier, Inc.