Chapter 1.Introduction

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Nov 30, 2013 (3 years and 17 days ago)

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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,<<Heart and movement of
blood>> 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
)


<1>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
-


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


<2> Feedback


control system(
反馈控制系

) 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.