Chapter 1.Introduction Section I subjects studied in Physiology 冯鉴强 教授

Concept of Physiology Physiology belongs a branch of biology What is Physiology?

Physiology is the science of studying the functional activities and its mechanisms in biological body. For example: why can heart automatically beat?

Physiology is also an experiment science.Why? the theories about the functional activities are based on the experiments British physiologist, William Harvey set up the modern physiology. Observed that blood flows in heart and vascular system.

In 1628, > was published. It is the first book of physiology based on experiment.

Field of Physiology Each type of life has its own functional characteristics. Physiology can be divided into viral physiology, bacterial physiology, cellular physiology, plant physiology, human physiology, and many more subdivisions.

Human physiology is the science of studing the rule of physiological functions in human body.

Animal experiments had become the main way to study physiology, why?

Why must the medical students study human physiology? Medical science development is closely related to physiology. (1) The classical traditional chinese medicine textbook( 内经 )presented much knowledge about 经络 and 脏腑 to guide the medical practice.

(2) Physiology provides the theories to explain many diseases. (3) Clinical practices test whether the physiological theories are correct or not and promote development of physiology.

Investigation levels and methods physiology A) Investigation levels (1) Cell and Molecular level The basic living unit of the body is the cell, and each organ is an aggregation of many different cells held together by intercellular supporting structures. Cell level research to understand the function of the organ.

The physiological characteristics of cells depend on the physical and chemical features of the big chemical molecules consisting of the cells. molecular level research to study the functions of cells. For instant: myocute contraction

Gene expression can also influence the functions of cells. Gene levels research molecular biological methods for molecular level and cell level research

Organ and system levels The goals are to explore the effects of organs and systems for human body and how to performe their activities, and the affecting factors.

For example: What is the function of respiratory system? How are the exchange of O2 and CO2? Which factors can influence this exchange process? Organ and System Physiology

Integral level The aims are to study interactions among organs and systems, and interaction between human body and environment.

Human being has complicated emotional activity and psychological activity, these activities can affect many somatic activity( 躯体活动 )and visceral activity( 内脏活动 )and cause the relative behavior.

To develop integrative physiology

Experiment methods for physiological study (1)acute experiment( 急性实验 ) A Experiment in vitro( 离体实验 ) Advantages: a) experiment condition is easy to be controlled. b) To easily analyze the results

B Experiment in vivo( 在体实验 ) (2)Chronic experiment( 慢性实验 ) Many conditioning reflex experiments are chronic experiments. Advantages: a) To observe continuously the activities in conscious condition; b) The findings are similar to physiological state.

Shortcoming: The conditions in the body are so complicated to analyze the results.

How to study human Physiology well? Prepare the lesson before the new one Combine physiological theory with the experiment Perform the experiments yourself and analyze the results with theories you have learned.

Section II Internal environment and Hemeostasis( 内环境和稳态 ) Internal environment of extracellular fluid( 细胞外液 ) body fluid:(1)intracellular fluid 2/3 (2) extracellular fluid 1/3

extracellular fluid: (1)plasma 1/4 (2)interstial fluid and fluid inside the cavaties (greater periotoneal body cavaty etc.) 3/4

In the extracellular fluid are ions and nutrients needed by the cell. All cells live in essentially the same environment,the extracellular fluid called the internal environment, a term introduced more than 100 years ago by French physiologist claude Bernard.

Homeostasis used by physiologists to mean maintenance of constant conditions in the internal environment. All of the organs and tissues perform function to help maintain these constant conditions.

For instant: lungs provide oxygen Kidneys maintain ions concentrations U.S.A Physiologist Walter Canmon combined “ Homeo ” with “ stasis ” to make up the term, Homeostatis.

Homeostatis the various physiological arrangements which serve to restore the normal state, once it has been disturbed. Including tow meaning: (1)relatively stable (2)the control process maintaining the constant conditions of internal environment

Section III Regulation of Body Functions

Nervous regulation ( 神经调节 ) Reflex: the basic active manner of nervous regulation Reflex arc: including 5 parts: Receptor-- >afferent->reaction center->efferent- >Effector Conditioning reflex and unconditioning reflex Conditioning reflex: set up after birth Unconditioning reflex: set up before birth

Humoral regulation ( 体液调节 ) including: (1)hormonal regulation: the hormones secreted by endocrine glands act on the receptors of cells (2)local chemical regulation: paracrine

Nervous - Humoral regulation( 神经体液调节 ) Many endocrine glands are not independent on nervous system, they are regulated directly or indirectly by nervous system, so the humoral regulation is believed as one loop of nervous system, i.e. nervous – humoral regulation

For example: Sympathetic nerve excites->E.P and noradrenaline secreted by medulla of adrenal gland->α 、 ß receptors excitation in cardiac vascular system- > heart rate ↑ and blood vessels contract -> BP ↑

Autoregulation( 自身调节 ) The regulation is not dependended on nervous system or homoral regulation. The cells or tissues themselves can response to stimulus. For instant: vascular smooth muscles can contract when they are stimulated by stretch stimuli.

Section IV Control systems of the body

To use cybernetics concept to analyze the functional regulation in human body (1)Non – automatic control system ( 非自动控 制系统 ) belongs open loop system( 开环系统 ) Feature: controlled system does not affect the activities of control system. For instant: depress reaction

Feedback – control system( 反馈控制系 统 ) belongs a closed loop system( 闭环系统 ) automatic control ( 自动控制 ) （ 1 ） Negative feedback: the more product or result you have, the less you get. For example: the arterial pressure – regulating mechanism.

(2)Positive feedback: the more product of result you have, the more you get. For instance: childbirth, the generation of nerve signals.