Download Chapter 1.Introduction

Chapter 1.Introduction
Instructor：
Dr Yao Yang
Text book
syllabus
•
chapter
content
Class hour
chapter1
Introduction
2
chapter2
The cell and its fuction
10
chapter3
Blood
6
chapter4
Blood circulation
20
chapter5
Respiration
10
chapter6
Digestion
6
chapter7
Energy metabolism
4
chapter8
Kidney
10
chapter9
Sense organs
4
chapter10 Nervous system
14
chapter11
10
Endocrine system
chapter12 Reproduction
2
Assessment
• Final exam: 80%
• Physiology experiment:20%
attendence
lab report
Section I subjects studied in
Physiology
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.
Why must the medical students
study human physiology?
• Medical science development is closely
related to physiology.
• (1) Physiology provides the theories to
explain many diseases.
• (2) Clinical practices test whether the
physiological theories are correct or not
and promote development of physiology.
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.
Experiment methods for
physiological study
(1)acute experiment
A Experiment in vitro
Advantages:
a) experiment condition is easy to
be controlled.
b) To easily analyze the results
B Experiment in vivo
(2)Chronic experiment
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.
Investigation levels in
physiology
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.
For example: myocyte contraction
2.Organ and system levels
• The goals are to explore the effects
of organs and systems for human
body and how to perform their
activities, and the
affecting factors.
3. Integral level
• The aims are to study interactions
among organs and systems, and
interaction between human body and
environment.
Section II Internal environment
and Homeostasis
Body Fluid = 60% of Body Weight (BW)
Plasma 5% of BW
Extracellular Fluid
1/3, 20% of BW
Interstitial Fluid
15% of BW
70 kg Male, 42 L
Intracellular Fluid
2/3, 40% of BW
• The extracellular fluid provides all
cells with a constant environment to
live in. For this reason, the
extracellular fluid is called the
internal environment of the body , a
term introduced more than 100 years
ago by French physiologist Claude
Bernard.
Plasma 5% of BW
Extracellular Fluid
1/3, 20% of BW
Internal Environment
Interstitial Fluid
15% of BW
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
Homeostasis
• the various physiological arrangements
which serve to restore the normal state,
once it has been disturbed.
• Including two meanings:
(1)relatively stable
(2)the control process maintaining the
constant conditions of internal
environment
Section III Regulation
of Body Functions
•
•
•
Nervous regulation
Reflex: the basic active manner of nervous
regulation
Reflex arc: including 5 parts: Receptor>afferent->nervous center->efferent>Effector
Conditioning reflex and unconditioning
reflex
Conditioning reflex: set up after birth
Unconditioning reflex: set up before birth
• Nervous regulation is characterized
by rapidity and accuracy in response,
and often shorter in duration.
Humoral regulation
• including:
(1)hormonal regulation:telecrine
the hormones secreted by endocrine
glands act on the receptors of cells
(2)local chemical regulation: paracrine
• Compared with the nervous regulation,
humoral regulation is, generally
speaking, slow in onset, diffuse in
nature, and often longer in duration.
Nervous - Humoral regulation
• 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
Autoregulation
• The regulation is not depended on
nervous system or homoral regulation.
The cells or tissues themselves can
response to stimulus. It is a
supplementary mechanism to the
major control systems.
• 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
belongs open loop system
Feature: controlled system does not
affect the activities of control
system.
For instant: depress reaction
• 2. Feedback – control system
• belongs a closed loop system automatic
control
• A. Negative feedback: Negative
•
feedback signals always produce an
effect opposite to that produced by
the initiating stimulus .
For example: the arterial pressure –
regulating mechanism.
maintaining homeostasis
Negative feedback
B. Positive feedback: In positive
feedback control system, deviations
from the steady state are actually
amplified, rather than diminished,
by the feedback loop. That is, a
positive feedback circuit intensifies
the activity of the control system.
• For instance: micturition reflex,
parturition, blood coagulation.
C. Feed-forward control system.
In feed-forward control system, control
part sends control signals to regulate
activity of controlled part. At same time
feed-forward signals is sent to controlled
part via other rapid pathways. For example:
conditioned reflex.
Compared with negative feedback control,
feed-forward control is rapid, predictive,
but sometimes cause lapsus.
Key points
1.
2.
3.
4.
5.
Internal environment
Homeostasis
Regulation of Body Functions
Positive feedback
Negative feedback