血管功能
夏强，PhD
浙江大学基础医学系
学习目标
• 学生在学完本部分后，能够：
– 列出三种类型的血管，并描述它们的结构与功
能
– 说出循环系统的两个环路，追溯血液从心脏出
发到任意器官、以及回到心脏的路径
– 定义脉搏
– 描述影响动、静脉及毛细血管血压和血流的因
素
– 定义高血压，区分收缩压与舒张压
– 描述淋巴系统的结构与功能
?
Functional parts of blood vessels
Hemodynamics
• Blood flow
Q= DP/R = (P1-P2)/R
Poiseuille Law: Q=pDPr4/8hL
h: viscosity
r: radius of the vessel
L: length of the vessel
Q= DP/R
R= 8hL/pr4
Arterial blood pressure
Systolic pressure (SP，收缩压): the
maximum arterial pressure
reached during peak ventricular
ejection
Diastolic pressure (DP，舒张压): the
minimum arterial pressure just
before ventricular ejection begins
Pulse pressure (PP，脉压): the
difference between SP and DP
Mean arterial pressure (MAP，平均动
脉压): the average pressure in the
cardiac cycle (=DP+1/3PP)
To estimate systolic and diastolic pressures, pressure is
released from an inflatable cuff on the upper arm while
listening as blood flow returns to the lower arm.
查DynaMed
Classification of blood pressure for adults
age 18 years and older
Blood Pressure Classification Chart
Category
Systolic (mm Hg)
Diastolic (mm Hg)
Normal
Lower than 120
Lower than 80
Prehypertension
120 - 139
80 - 89
Stage 1
140-159
90-99
Stage 2
160 or higher
100 or higher
Hypertension
Adapted from The Seventh Report on the joint National Committee on Prevention,
Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), NIH Publication
No. 03-5233, May 2003
The classification chart is based on adults, aged 18 and older, who are not taking high
blood pressure medicines and who are not acutely ill. If systolic and diastolic
measurements fall into different categories, the higher category should be used to
classify the person's blood pressure status.
中国高血压防治指南（2010年修订版）
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Arterial Pulse
In response to the pulsatile contraction of the heart:
pulses of pressure move throughout the vasculature,
decreasing in amplitude with distance
Systematic examination of pulses:
Which and what order?
1. Radial artery
Where and how?
Why?
•Radial side of wrist.
•With tips of index and middle fingers.
•To assess rate and rhythm.
•Simultaneously with femoral to detect
delay.
•Not good for pulse character.
2. Brachial artery
•Medial border of humerus at elbow medial to biceps
•To assess pulse character.
tendon.
•To confirm rhythm.
•Either with thumb of examiner's right hand or index and
middle of left hand.
3. Carotid artery
•Press examiner's left thumb against patient's larynx.
•Press back to feel carotid artery against precervical
muscles.
•Alternatively from behind, curling fingers around side of
neck.
4. Femoral artery
•Patient lying flat and undressed.
•To assess cardiac output.
•Place finger directly above pubic ramus and midway
•To detect radiofemoral delay.
between pubic tubercle and anterior superior iliac spine. •To assessperipheral vascular disease.
5. Popliteal artery
•Deep within the popliteal fossa.
•Compress against posterior of distal femur with knee
slightly flexed.
•Mainly to assess peripheral vascular
disease.
•In diabetics.
6. Dorsalis pedis (DP) and tibialis
posterior (TP) arteries (foot)
•Lateral to extensor hallucis longus (DP).
•Posterior to medial malleolus (TP).
•As above.
7. The abdominal aorta
•With the flat of the hand per abdomen, as body habitus •In peripheral vascular disease.
allows.
•To detect aneurysmal swelling.
•Best for pulse character and, to some
extent, left ventricular function.
•To detect carotid stenosis.
•At resuscitation (CPR).
From: http://www.patient.co.uk/
Microcirculation
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A-V shunt
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Arterioles（微动脉）
Two major roles:
• To be responsible for determining the relative blood
flow in individual organs at any given MAP
• To be a major factor in determining MAP
Dynamic adjustments in the blood distribution to the
organs is accomplished by relaxation and contraction
of circular smooth muscle in the arterioles.
Local Control of Blood Flow
• The mechanism independent of nerves or
hormones by which organs and tissues
alter their own arteriolar resistances,
thereby self-regulating their blood flows
– Active hyperemia（主动充血）
– Flow autoregulation（血流自身调节）
– Reactive hyperemia（反应性充血）
– Local response to injury（对损伤的局部反应）
Local control of organ blood flow
Active hyperemia and flow autoregulation differ in their
cause but both result in the production of the same
local signals that provoke vasodilation.
Extrinsic Control
• Sympathetic nerves（交感神经）
• Parasympathetic nerves（副交感神经）
• Noncholinergic, nonradrenergic autonomic
neurons (NO or other noncholinergic
vasodilator substances)（NANC）
• Hormones (epinephrine, angiotensin II,
vasopressin, atrial natriuretic peptide)
Sympathetic stimulation of alpha-adrenergic receptors cause
vasoconstriction to decrease blood flow to that location.
Sympathetic stimulation of beta-adrenergic receptors lead to
vasodilation to cause an increase in blood flow to that location.
Renin-angiotensin system（肾素-血管紧张素系统）
ANGII can be produced directly
by conversion of
angiotensinogen by the tissue
plasminogen activator (tPA),
cathepsin G and tonin or by
hydrolysis of angiotensin I by
chymase and cathepsin G.
CAGE = chymostatin-sensitive angiotensin
II-generating enzyme
Vasopressin（血管升压素）
Endothelium-derived vasoactive substances
•Vasodilator factors
•PGI2 – prostacyclin（前列环素）
•EDRF (endothelium-derived relaxing factor, nitric oxide)
•EDHF (endothelium-dependent hyperpolarizing factor)
Vasoconstrictor factors – Endothelin-1（内皮素-1）
Major factors affecting arteriolar radius
Diversity among signals that influence contraction/relaxation
in vascular circular smooth muscle implies a diversity of
receptors and transduction mechanisms.
Capillaries
Relationship between total cross-sectional area and
flow velocity
Six balls in per minute
mandates six balls out per minute.
Therefore, the velocity of the balls in the smaller tubes is slower.
Capillary walls
are a single
endothelial cell
in thickness.
The capillary is
the primary point
exchange between
the blood and the
interstitial fluid (ISF).
Intercellular clefts
assist the exchange.
There are many, many capillaries, each with slow-moving
blood in it, resulting in adequate time and surface area
for exchange between the capillary blood and the ISF.
Movement of fluid and solutes out of the blood is called filtration.
Filtration
Absorption
Movement of fluid and solutes into the blood is called absorption.
Net filtration pressure (or Effective filtration pressure)
Effects of arteriolar vasodilation or vasoconstriction on capillary blood pressure
Dynamic changes in vasodilation/vasoconstriction in the
arterioles regulate downstream pressures and flow rates.
Venous pressure and venous return
• Venous pressure
– Peripheral venous pressure
（外周静脉压）-- the
pressure in the peripheral veins
– Central venous pressure (CVP，
中心静脉压) -- the pressure in
the thoracic vena cava & the
right atrium 4~12cmH2O
Determinants of venous pressure
• Contraction of venous smooth muscle
– Sympathetic neurons
– Hormonal and paracrine vasodilators
and vasoconstrictors
• Skeletal muscle pump
• Respiratory pump
Varicose vein（曲张静脉）
• Skeletal muscle pump
• Respiratory pump
Alterations in “venous return” alter end-diastolic volume (EDV);
increased EDV directly increases stroke volume and cardiac output.
The Lymphatic System
Lymphatic pump
Elephantiasis
Also known as lymphatic filariasis, this condition
occurs when parasitic worms (any of several types
of filaria worms) infest the lymphatic system. The
filaria are transmitted by mosquitoes to the blood
and can build a population in the lymph nodes,
blocking fluid drainage from arms, legs, genitals, or
breasts. It is called elephantiasis (literally,
"elephant condition") because in extreme cases,
the arms and legs look like the limbs of an elephant.
Elephantiasis affects over a 100 million people
around the world. However, most cases are not as
extreme as in this photo!
A summary of dynamic changes in MAP and TPR.
The End.