Transcript 01-Introduction

Medical Education
• Memory competition?
Learning methods vs
knowledge keeping
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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.”
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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: [email protected]
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, McGrawHill.
Course website
• Course website:
• http://m-learning.zju.edu.cn
• Demo
Physiology: the study of the
logic of life
生
理
学
Life
Logic
Study
Viral
Physiology
……
Bacterial
Physiology
Physiology
Human
Physiology
Animal
Physiology
Plant
Physiology
Human Physiology
• Specific characteristics,
functions and mechanisms
of the human body that
make it a living being
What ?
How ?
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
internal environment
external
environment
Internal environment
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
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
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Concentration of nutrients and waste products
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Concentration of salt and other electrolytes

Volume and pressure of extracellular fluid
How is homeostasis achieved?
----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
Homeostasis and Illness
Regulation of body functions
• Nervous Regulation
• Humoral Regulation
• Autoregulation
Nervous regulation
Reflex
Knee jerk reflex
Reflex Arc
•Receptor
•Afferent (sensory) nerve
•Reflex center (brain or spinal cord)
•Efferent (motor) nerve
•Effector
Humoral regulation
Hormone
Traditional description of humoral
regulation by hormone
Endocrine
cells
Receptor
Hormone
•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
Neuroendocrine
(Neurosecretion)
Vasopressin
Oxytocin
Autoregulation
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
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
1. Non-automatic Control System
Open-loop system
Seldom seen under physiological conditions
Stress
Stimulus
Control Center
Effectors
Response
2. Feedback Control System
Stimulus
Control Center
Closed-loop system
Automatic control
Negative feedback
Positive feedback
Effectors
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
Gain=
Correction
Error
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
Monitor
Stimulus
Control
Center
Disturbance
Effector
s
Response
Summary
• Terms:
• Internal environment
• Homeostasis
• Negative feedback
• Positive feedback
• Regulation of body functions
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