Medical Education

• Memory competition?

Learning methods vs knowledge keeping• listening = 5%

• reading = 10%

• audio-visual = 20%

• demonstration = 30%

• discussion = 50%

• hands-on = 75%

• teaching/using = 90%

Graduate Attributes and Capabilities

• Attitudes

• Knowledge

• Skills

Learning Philosophy

• I hear and I forget,

• I see and I remember,

• I do and I understand.

Dr. Charles Sidney Burwell(Dean of HMS from 1935 to 1949)

• At an HMS graduation in the late 1940s, he said “…Half of what we have taught you is wrong. Unfortunately, we don’t know which half.”

• Dr. Burwell was a cardiologist who specialized in circulation changes associated with heart disease. He is credited with bringing attention to obstructive sleep apnea syndrome. In 1944, while Dr. Burwell was Dean, women entered Harvard Medical School for the first time on an equal basis with men.

"It has been estimated that, from the beginning of civilization — 5,000 years

ago or more — until 2003, humanity created a total of five exabytes (billion

gigabytes) of information. From 2003 to 2010, we created this amount every two

days. By 2013, we will be doing so every ten minutes, exceeding within hours

all the information currently contained in all the books ever written.

So it isn't that we need more knowledge; it is that we need to distinguish

between what we know and what we don't know, through what Firestein calls

“controlled neglect”. Researchers must selectively ignore vast quantities of

facts and data that block creative solutions, and focus on a narrow range of

possibilities.

"To make discoveries, researchers need to look beyond the facts.”

Ignorance includes an important discussion about scientific errors and their

propagation in textbooks. I admit that I passed one on in my last book, The

Believing Brain (Times Books, 2011): I repeated as gospel the 'fact' that the

human brain contains about 100 billion neurons. Firestein reports that it is

actually around 80 billion, and that the number of glial cells is an order of

magnitude smaller than most textbooks state.

The 'neural spike' recorded by neuroscientists as a fundamental unit of brain

activity, Firestein reminds us, is an artefact of our measuring devices and

ignores other forms of neural activity. Even the famous and widely printed

'tongue map', which shows sweet flavours sensed on the tip of the tongue,

bitter on the back and salt and sour on the sides, is wrong — the result of a

mistranslation of a German physiology paper. These and other errors arise as a

result of our lack of scepticism towards the knowledge we have.”

Handheld device software

• Archimedes: medical calculator• >150 equations• Unit exchange

• Epocrates: drugs manual• >3300 drugs• More than 45% medical doctors used

• DynaMed: evidence based medicine database

Introduction to Human Physiology

XIA Qiang, MD & PhD

Department of Physiology

Room 518, Block C, Research Building

School of Medicine, Zijingang Campus

Email: xiaqiang@zju.edu.cn

Tel: 88206417 (Undergraduate school),

88208252 (Medical school)

Course Structure

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

• Practicals: 64 a.h.• 4 a.h./week• Begin from second week (3/3)

Evaluation

• Participation: 5%

• Practical reports: 15%

• Weekly assessments, mini-tests at lecture & midterm exam: 30%

• Final examination: 50%

Recommended textbook

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

Course website

• Course website:• http://m-learning.zju.edu.cn

• Demo

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 ?

Body Components

• Differentiated Cells - specialized function

• Tissues - groups of cells with related function (muscle, nervous, connective, & epithelium)

• Organ- functional unit

• Organ system – several organs act together to perform specific function

skin = barrier entry = respiratory & GI transport = CV & diffusion exit = renal & GI

Fluid Compartments

ICF ISF plasma organs

external environment internal environment

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

Extracellular Fluid=Internal Environment

Homeostasis

•Homeostasis (from the Greek

words for “same” and “steady”):

maintenance of static or

constant conditions in the

internal environment

•Central theme of physiology Walter B. 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?

Homeostasis and Illness

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)

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

Effectors

Stimulus Response

MonitorMonitorDisturbance

Summary

• Terms:

• Internal environment

• Homeostasis

• Negative feedback

• Positive feedback

• Regulation of body functions

THANK YOU FOR YOUR ATTENTION!