Download 胜肽奈米膠在心臟幹細胞治療之前臨床研究

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Learning objectives
2013 Sp. BME-- Introduction to BME
1. Understanding the circulatory system consists of a
circulating fluid, a system of vessels, and a pump
2. The composition of blood and the role of cells in
determining blood’s physical properties
Circulation
3. The general structure of the vascular system-• the relationship between vessel radius, resistance to
flow, and pressure drop
• the function of capillaries in flow distribution and
transport of molecules
Patrick C.H. Hsieh (謝清河), M.D., Ph.D.
Institute of Clinical Medicine, Dept. of Surgery & Dept. of Biomedical Engineering
National Cheng Kung University & Hospital, Tainan, Taiwan
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
Department of Bioengineering, University of Washington, Seattle, WA, USA
4. The anatomy of the heart and the electrical system-• the events in the cardiac cycle
• the generation of pressure
國立成功大學 暨 成大醫院 臨醫所,外科 暨 醫工系
中央研究院 生醫所
美國 華盛頓大學 生物工程系
Why circulation is important?
Composition of circulating fluid
Whole blood-- plasma and blood cells
1. Transporting O2 and other
nutrients
2. Removing waste products
3. Maintaining homeostasis
(body temperature, blood
pressure and pH)
Heart-- pump;
Vasculature– plumbing;
Blood-- circulated fluid
•
Plasma-- 55%
 Electrolytes < 1%
 Proteins < 7% (albumin, globulins etc.)
 Water 93%
•
Blood cells-- 45%
 Erythrocytes
 Leukocytes
 Platelets
 Circulating stem/
progenitor cells
The blood vessels
vein
Allergic
Acute
inflammation diseases
Immediate
-type
hypersensitivity
artery
Chronic
inflammation
capillary
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Pressure drop in circulatory system
Blood flow through a cylindrical vessel
The Navier-Stokes equations
(Text: Box 8.2)
Why?
dramatic pressure decrease in arterioles
Q: blood flow rate
Δp: pressure drop
Flow rate, pressure and resistance
rv: radius of the vessel
μ: fluid viscosity
: fluid density
L: length of the vessel
Homeostasis– control of local organ flow
simplifying
R ∝ rv−4
1/30
 the greatest overall resistance
is provided by arterioles
 Arterioles have muscular walls
to adjust their diameter
 local blood flow to a tissue is
controlled by constriction and
dilation of the arterioles
delivering blood to that tissue
Turbulent flow is atherogenesis
Laminar flow & turbulent flow
Vessel compliance and elasticity
Atherogenesis
∝ E-1
high compliant
low elastic
C: blood vessel compliance
E: blood vessel elasticity
ΔV: change in vessel volume
for a given Δp
Δp: change in hydrostatic pressure
Mechanotransduction:
Studies of mechanisms by which cells
convert mechanical stimulus into
biochemical activity
• An elastic artery allows it to serve as a “pressure reservoir”
- Without vessel elasticity, the pressure of aorta will change
dramatically during systole and diastole
Shu Chien (錢煦院士)
Fellow of National Medal of
Science, American Academy of
Arts and Sciences, National
Academy of Engineering and
National Academy of Sciences
low compliant
high elastic
Nat. Rev. Mol. Cell Biol. 2009
• A compliant vein allows it to serve as a “volume reservoir”
- high compliance enables veins to expand greatly in volume
with a small increase in pressure
Figure 22.5
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Structure and function of capillaries
Anatomy of the heart
• exchange of molecules, e.g. O2, CO2, glucose, nutrients
• fenestrated monolayer
• every metabolically active cell is within 100 μm of the
nearest capillary for diffusion of molecules
• diameter of capillaries ~ size of red blood cell (6–8 μm)
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Figure 22.5
Path of blood through the heart
Excitability-contraction coupling
in cardiac cells
Electrical activity of the heart
The cardiac cycle
LV pressure-volume loop
(pacemaker)
A, mitral valve open
B, late diastole
C, mitral valve close
D, aortic valve open
E, LV eject
F, aortic valve close
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Summary
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The cardiovascular system is composed of a pump, the heart, which
circulates a specialized fluid, blood, through an elaborate system of
branched vessels.
The blood is a special fluid composed of cells dispersed in a protein-rich
fluid called plasma. White blood cells are involved in the inflammatory
response and immune function; RBCs transport oxygen to tissues.
The blood circulates in the body through a network of vessels including
arteries, veins, and capillaries.
Many of the biophysical properties of the circulation can be deduced
using a simple engineering model: fluid flow in a straight cylindrical tube.
The heart is equipped with a muscular wall that contracts to pump blood
from its chambers (atria and ventricles) to other parts of the body.
The heart’s muscular wall is made up of self-excitable cardiac cells that
contract in response to electrical stimulation.
The heart contracts rhythmically to create blood pressure, which drives
blood flow.
Questions
1. Veins and capillaries are both low-pressure vessels. Why
do veins typically have thicker, stronger walls than
capillaries?
2. How is compliance related to wall tension in the wall of a
vessel? Which type of vessel is more compliant: veins or
capillaries? What property allows these vessels to be
more compliant? What function does this higher
compliance serve?
3. Using library resources, investigate what a pacemaker
(the medical device, not the natural pacemaker tissues of
the heart) is and how it works. Why is it important to
control a patient’s heart rate?
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