Introduction to Human Physiology

XIA Qiang, M.D. & Ph.D.

Department of Physiology

Room 518, Block C, Research Building

School of Medicine, Zijingang Campus

Email: xiaqiang@zju.edu.cn

Tel: 88208252

Course Structure

• Lectures: 80 academic hours• 5 a.h./week• 2 a.h. on Tue., 3 a.h. on Fri.

• Practicals: 64 a.h.• 4 a.h./week

Evaluation

• Participation in practicals: 5%

• Practical reports: 15%

• Weekly assessments & midterm exam: 20%

• Final examination: 60%

Recommended textbook

• Widmaier EP, Raff H, Strang KT (2006) Vander’s Human Physiology: The Mechanisms of Body Function, Tenth Edition. McGraw-Hill.

Course website

• University Course Center: • http://10.202.77.12/

• Course website:• http://10.202.77.12/JWCenterWeb/TemplateVi

ew?tempName=null&id=null&websiteId=26519&type=1&codeName=columnsun&courseWebsiteId=69995

Physiology: the study of the logic of life

Life

Logic

Study

生理学

Physiology

Plant Physiology

Bacterial Physiology

Viral Physiology

Animal Physiology

Human Physiology

……

Human Physiology

• Specific characteristics, functions and mechanisms of the human body that make it a living being

How ?What ?

Exercise Physiology

Aviation, high-altitude, and space physiology

Diving and Hyperbaric physiology

C. Galen (129-200)

(Ancient Greco-Roman)

History of Physiology

Leonardo da Vinci (1452-1519) (Italian)

De Motu Cordis

“On The Motion Of The Heart And Blood In Animals” (1628)

(http://www.fordham.edu/halsall/mod/1628harvey-blood.html)

W. Harvey (1578-1657) (English)

Rise of modern physiology

An Italian physiologist who

used a microscope to

discover the capillaries,

crowning Harvey’s

investigation

M. Malpighi (1628-1694)

L. Galvani (1737-1798) (Italian)

(1813-1878)

A French physiologist known

for his idea of the internal

environment

Павлов (Ivan Pavlov) (1849-1936)

A Russian physiologist known

chiefly for his development of

the concept of the conditioned

reflex

Awarded the Nobel Prize for

Physiology or Medicine in 1904

中国生理学会 Chinese

Association for

Physiological

Sciences

(founded in

1926)

林可胜 (Robert Kho Seng Lim) (1897-1969)“Father of Chinese Modern Physiology”

Levels of Physiological research

1. Cellular and molecular Physiology

Measurementof cell shortening

Ce

ll le

ng

th (m

)

120

905s

Measurement of [Ca2+]i

0.6

1.3

340

/380

5s

2. Organ and System Physiology

3. Integrative Physiology

Acute experiment

Chronic experiment

Body Fluid = 60% of Body Weight (BW)

Intracellular Fluid2/3, 40% of BW

Extracellular Fluid1/3, 20% of BW

Plasma 5% of BW

Interstitial Fluid15% of BW

70 kg Male, 42 L

Internal environment

External Environment

Extracellular Fluid1/3, 20% of BW

Plasma 5% of BW

Interstitial Fluid15% of BW

Internal Environment

Extracellular Fluid=Internal Environment

Homeostasis

Homeostasis (from the

Greek words for “same”

and “steady”):

maintenance of static or

constant conditions in

the internal environment

W. Cannon

Components of Homeostasis:

Concentration of O2 and CO2

pH of the internal environment

Concentration of nutrients and waste products

Concentration of salt and other electrolytes

Volume and pressure of extracellular fluid

----Regulation

Body's systems operate together to

maintain homeostasis:

Skin system Skeletal and muscular system

Circulatory system Respiratory system

Digestive system Urinary system

Nervous system Endocrine system

Lymphatic system Reproductive system

How is homeostasis achieved?

Regulation of body functions

• Nervous Regulation

• Humoral Regulation

• Autoregulation

Reflex

Knee jerk reflex

Nervous regulation

•Receptor

•Afferent (sensory) nerve

•Reflex center (brain or spinal cord)

•Efferent (motor) nerve

•Effector

Reflex Arc

Endocrine cells

Hormone

Hormone

Receptor

Traditional description of humoral regulation by hormone

Humoral regulation

•Endocrine action: the hormone is distributed in

blood and binds to distant target cells•Paracrine action: the hormone acts locally by

diffusing from its source to target cells in the

neighborhood•Autocrine action: the hormone acts on the same

cell that produced it

VasopressinOxytocin

Neuroendocrine

(Neurosecretion)

• Pheromone

Pheromone for MenOriginal price: $99.95

Ant Alarm Pheromone

Definition: Intrinsic (independent of any neural or humoral influences) ability of an organ to maintain a constant blood flow despite changes in perfusion pressure

Mechanism: Stretch-activated constriction of vessels

Significance: Maintenance of near-constant cerebral, renal and coronary blood flow

Autoregulation

80~180 mmHg

Control systems of the body

CYBERNETICS

or Control and Communication

in the Animal and the Machine

(MIT Press 1948)

Norbert Wiener (1894-1964)Originator of Cybernetics

Open-loop system

Seldom seen under physiological conditions

Stress

1. Non-automatic Control System

Control Center EffectorsStimulus Response

Closed-loop system

Automatic control

Negative feedback

Positive feedback

2. Feedback Control System

Control Center EffectorsStimulus Response

Negative feedback: common

A change in a condition leads to responses from the

effectors which counteracts that change

Examples:

Regulation of blood pressure,

Regulation of body temperature,

Regulation of hormone release…

Gain of the negative feedback:

The degree of effectiveness with which a control

system maintains conditions

Correction

ErrorGain=

Positive feedback: uncommon

A change in a condition leads to responses from the

effectors which amplifies that change

+

Examples:

Child birth

Micturition

Blood coagulation

Vicious circle under pathophysiological conditions…

3. Feed-forward Control

Often seen in nervous system

Rapid

Adaptive control

Examples: some muscle contraction,

conditioned reflex

Control Center EffectorsStimulus Response

MonitorMonitorDisturbance

Summary

• Terms:

• Internal environment

• Homeostasis

• Negative feedback

• Positive feedback

• Regulation of body functions

THANK YOU FOR YOUR ATTENTION!