Physiology Da-Nian Zhu

INTRODUCTION Chapter 1 § 1. Physiology & its research field  Definition of physiology  The task of physiological research * How * Why * Influence of environment * Adaptation and regulation

 Relationship between medicine & physiology * Physiology is one of basic medical sciences  Three levels of physiological research * Cellular & molecular level * Organic & systemic level * Integrative level  Methods of physiological research * Acute and chronic animal experiment * in vitro & in vivo experiment * molecular biological experiment

§ 2. Internal environment of the body  Body fluid (60% of body weight) * Intracellular fluid (40%) * Extracellular fluid (20%) Plasma (5%) Interstitial fluid (15%) Lymph (<1%) Cerebrospinal fluid (<1%) Aqueous humor (<1%) etc.

Distribution & transfusion of body fluid

 Concept of internal environment (’1870) By Claude Bernard (1813-1878) milieu interne [`mi:lj: `int:n] [French]  Concept of homeostasis (’1920) By W. B. Cannon (1871-1945)  Importance of maintaining the homeostasis * Enough nutritional substances & O2 * Low level of metabolic products & CO2 * Water, electrolyte, acid-base balance * Temperature, osmotic pressure, etc.  Homeostasis is a dynamic equilibrium  Regulation of homeostasis * Involve all systems, especially the lung & kidney

§ 3. Regulation of physiological function  Nervous regulation * Definition & the characteristics * Reflex & reflex arc  Humoral regulation * Hormone & its secretory forms Telecrine, paracrine, neurosecretion, etc.  Autoregulation

Reflex & reflex arc

§ 4. Automatic control system in the body  Non-automatic control system Open loop system  Feedback control system * Closed loop system, Automatic control * Negative feedback system * Positive feedback system  Feed-forward control system More quickly, less oscillated & foresighted

Feed-forward signals Receptor Center Effector Feedback signals