Download Chapter 4 Circulation

Circulatory system (循环系统)
„
Circulatory system: heart + blood vessels
„
Function: nutrient transportation and
metabolites returning
„
Blood: carrier
„
Heart: pump
„
Blood vessels: route, substance
communications
2014-04-21
生理与病理生理学系
1
Bioelectrical phenomenon of heart
„
Heart—muscular organ
„
Classification of cardiac muscle
„
„
Working cardiac muscles: atrial & ventricular muscle
„
Abilities: excitability, contractility, conduction
„
Specialized cardiac muscle:
„
Sinus node (sinoatrial node, SA node)
„
Atrioventricular (AV) node
„
AV bundles
„
Purkinje cells
„
Abilities: excitability, conduction, autorhythmicity
„
Specialized excitatory-conductive system
Internodal pathway——atrial muscles (anterior,
middle, posterior)
2014-04-21
生理与病理生理学系
2
Bioelectrical phenomenon of cardiac muscle
Transmembrane potentials
„
Resting potential
„
Action potential
„
Working and autorhythmic cardiac
muscle cell
2014-04-21
生理与病理生理学系
3
RP of working cardiac muscle cell
„
-90 mV
„
Ion basis:
Cardiac muscle
„
K＋ equilibrium potential
„
Slow leaking of Na+
„
Activity of Na+-K+ pump
„
ACh activated potassium channel:
hyperpolarization
2014-04-21
生理与病理生理学系
4
AP of working cardiac muscle cell
„
Complex, longer
„
Depolarization:
„
„
Phase 0: -90 ~ +30mV, 1 ms
Repolarization:
„
Phase 1 (initial rapid repolarization): +30 ~
0mV, 10 ms
„
Phase 2 (plateau): 0 mV, 100~150 ms
„
Phase 3 (final repolarization): 0 ~ -90 mV, 100
~ 150 ms
„
Phase 4 (resting potential): -90 mV
2014-04-21
生理与病理生理学系
5
Ion basis for AP of working cell
„
Phase 0：Na+ influx
„
Phase 1：K+ efflux
„
Phase 2:
„
Ca2+ influx: L-Ca2+ channels
„
K+ efflux
„
Phase 3: K+ efflux
„
Phase 4: resting potential
2014-04-21
生理与病理生理学系
6
AP in atrial muscle cell
„
Duration: shorter, 150ms
„
Reason: permeability to
K+ is higher
2014-04-21
生理与病理生理学系
7
Transmembrane potential in Purkinje cells
„
Characteristic:
„
Phase 4 potential level not stable
„
Maximal repolarizing potential ——maximal relaxation
potential
Working cell
2014-04-21
生理与病理生理学系
Purkinje cell
8
Transmembrane potential in Purkinje cell
„
Phase 0,1,2,3: same to working cell
„
Phase 4: automatic depolarization
„
Depolarization——net inward current
„
K＋channel inactivation: begins at -60mV
„
If current (pacemaker current)
„
Activated at -60 mV, full activation -100 mV
„
Na+ influx
„
Blocker: Cs
2014-04-21
生理与病理生理学系
9
AP in pacemaker cell of SA node
„
Maximal relaxation potential: -60 mV
„
Threshold: -40 mV
„
Automatic depolarization: Fast
„
Lack of phase 1, 2
„
Phase 0 depolarization: slow
0
-40
-60
2014-04-21
生理与病理生理学系
10
AP in pacemaker cell of SA node
„
Characteristic：
„
Lack of Ik1 ——maximal relaxation potential -60
mV——inactive Na+ channels——no Na+ influx in
0
phase 0
„
Phase 0: Ca2+ influx from L- Ca2+ channels，
„
Phase 3: K+ efflux
-40
„
Phase 4:
-60
„
K+ channel inactive at -60mV
„
If current: not fully activated, protective effect
„
ICa: activation of T- Ca2+ channels at -50mV
2014-04-21
生理与病理生理学系
11
Fast response and slow response cell
„
According to Phase 0
„
„
„
„
„
Fast Action P, fast Na+ channels ( fast response cell)
Slow Action P, slow Ca2+ channels (slow response cell)
Fast response cell: working cell, Purkinje cell
Slow response cell: Pacemaker cell
Autorhythmicity:
„
„
Autorhythmic cell: P cell, Purkinje cell
Non autorhythmic cell: working cell
2014-04-21
生理与病理生理学系
12
Electrical properties of cardiac muscle
„
„
Electrical properties
„
Excitability
„
Autorhythmicity
„
Conductance
Mechanical property
„
2014-04-21
Contractility
生理与病理生理学系
13
Excitability
„
Difference between RP and Threshold
„
ACh: hyperpolarization
„
Quinidine: inhibits the activation of
Na+ Channels——upshift threshold
(myocarditis: arrhythmia)
„
State of Na+ channels
„
Resting, activating, inactivating——
potential, temporal dependent
Resting
2014-04-21
生理与病理生理学系
Activating
Inactivating
Reliving
14
Excitability
„
Working cell
„
„
Effective refractory P: 0 ~ -60 mV
„
Absolute refractory P: 0 ~ -55 mV
„
Local response P: -55 ~ -60 mV
„
Relative refractory P: -60 ~ -80 mV
„
Supranormal P -80 ~ -90 mV
Pacemaker cell
„
Slow recovery: postrepolarization
refractoriness
2014-04-21
生理与病理生理学系
15
Significance of long-lasting refractory period
•
No tetanus
•
Premature contraction——
Compensatory pause (CP)
Premature C
CP
Cardiac contraction
SA node rhythm
Extra stimuli
2014-04-21
生理与病理生理学系
16
Autorhythmicity of specialized muscles
„
Definition: generates
impulses automatically
„
Number of impulse/min
2014-04-21
生理与病理生理学系
17
Normal rhythm of heart
„
All conductive tissues: intrinsic autorhythmicity
„
Ranks of autorhythmicity：
„
SA node >AV node >AV bundle >Purkinje cell
„
Normal Pacemaker——SA node (sinus rhythm)
„
Others——potential pacemakers (ectopic rhythm)
„
Significances of potential pacemakers
„
Dangerous : myocarditis
„
Protective: AV block
2014-04-21
生理与病理生理学系
18
SA node controls the heart beat
1.
Capture
2.
Overdrive suppression
„
„
„
Reasons: over activity of Na+-K+ pumps
„
Hyperpolarization
„
Counterbalancing inward current
Suppression: Frequency difference
Clinical significances
„
No arrhythmia with sudden lose of SA
rhythm
„
„
2014-04-21
(Sick sinus syndrome, SSS)
Artificial cardiac pacemaker
生理与病理生理学系
19
Factors influence autorhythmicity
„
„
Speed of depolarization
„
NE——increase If and ICa
„
ACh——increases IK＋
Difference between TP and
Max relaxation potential
„
ACh——hyperpolarization
2014-04-21
生理与病理生理学系
20
Conductance of AP in heart
„
„
Normal conductance:
„
Speed
„
Route
Abnormal: Arrhythmia (心律失
常)
2014-04-21
生理与病理生理学系
21
Conductance of AP in heart
„
Route:
„
SA node——atrial muscles——AV
node——AV bundles——Purkinje
cells——ventricular muscles
„
Electrical conductance
„
Gap junctions——MW < 1000—
—functional syncycium (atrial,
ventricular)
2014-04-21
生理与病理生理学系
22
Characters of AP conductance in heart
Speed
„
„
Fast in A and V, slow at AV node
„
Atria: 1.0 ~ 1.2 m/s; Ventricles: 2 ~ 4 m/s
„
AV node: 0.02 m/s
Significance:
„
Fast in A and V——synchronization
„
Slow at AV node——
2014-04-21
„
AV delay: Atria systole just before ventricular systole
„
AV block
生理与病理生理学系
23
Characters of AP conductance in heart
„
High frequency filtration
„
AP in atrial muscle: shorter duration
„
HR increase → refractory P decrease
„
AV node——postrepolarization
refractoriness
„
High frequency filtration: atrial
fibrillation
2014-04-21
生理与病理生理学系
24
Factors influence AP conductance
„
Diameter——current resistance
„
Purkinje cell > ventricular muscle > atrial
muscle >AV node
2014-04-21
生理与病理生理学系
25
Factors influence AP conductance
„
Speed and amplitude of depolarization:
„
Amplitude: resting P
„
Velocity: number of activated Na+ channel—
—potential, temporal dependent
„
State of channels in adjacent
membrane
2014-04-21
生理与病理生理学系
26
Electrocardiogram (ECG)
„
Each cardiac cycle, AP
from P cell precisely
spreads throughout the
heart according to exact
route, sequence——
Electrocardiogram (ECG)
2014-04-21
生理与病理生理学系
27
Waves in electrocardiogram
„
Set of electrocardiogram:
0.1mV/mm, 0.04 s/mm
„
Waves:
„
P wave: atrial depolarization,
0.08-0.11s
„
QRS complex: ventricle
depolarization, 0.06-0.10s
„
T wave: ventricle
repolarization, 0.05-0.25s
„
U wave: unclear, 0.1-0.3s
2014-04-21
生理与病理生理学系
28
Waves in electrocardiogram
„
Others：
„
P-R interval: AP spreads to
ventricle from SA node, 0.12 ~
0.20 s
„
Q-T interval: beginning of
ventricular depolarization to
completeness of repolarization
„
S-T segment: all ventricular
muscle stay at phase 2
2014-04-21
生理与病理生理学系
29
Relationship between ECG and AP
„
AP is the origin of ECG
„
Difference: Recording technique
„
AP——intracellular, single cell
„
ECG——extracellular, summation
2014-04-21
生理与病理生理学系
30
ECG and cardiac contraction
„
ECG:
Electrical activity
„
Cardiac muscle contraction:
Mechanical property
2014-04-21
生理与病理生理学系
31
Blood pumping process
„
„
Cardiac cycle & heart rate: 60~90/min
„
Systole
„
Diastole
Heart rat increase——cardiac cycle decrease
Time (S)
Atria
Ventricle
2014-04-21
S
D
D
S
生理与病理生理学系
D
32
Heart pumping process
„
Ventricular Systole
„
Isovolumic contraction
„
Ejection
„
Rapid ejection
„
Slow ejection
2014-04-21
生理与病理生理学系
33
Heart pumping process
„
Ventricular Diastole
„
„
Isovolumic diastole
Ventricular filling
„
Rapid filling
„
Slow filling
„
Atrial systole
2014-04-21
生理与病理生理学系
34
Role of atrial contraction
„
Primary pump
„
„
Increase ventricular
filling: 10-30%
Arial pressure
„
A wave: atrial systole
„
C wave: ventricular
systole
„
V wave: venous retuning
2014-04-21
a c
v
生理与病理生理学系
35
Functional evaluation of the heart pump
„
Cardiac output
„
Stroke volume (每搏输出量): 70 ml
„
Cardiac output (每分输出量, 心输出量): 5L
„
Cardiac index (心指数)
„
„
Cardiac output / body surface area
Ejection fraction (射血分数)
„
Stroke volume / End diastolic volume
2014-04-21
生理与病理生理学系
36
Functional evaluation of heart
„
Work output of heart
„
Stroke work output (每搏功) = internal (stroke output × pressure
difference)＋ external work
„
(stenosis): external work increase
„
Minute work output (每分功) = Stroke work output × heart rate
„
Efficiency of cardiac work output = work output / energy consumption
„
Normal value: 20~25 %
„
Heart failure: 5~10 %
„
Increase in artery pressure: decrease in efficiency
2014-04-21
生理与病理生理学系
37
Cardiac reservation (心脏功能贮备)
„
Resting state: 5L/min
„
Heavy excises: 30L/min
„
Cardiac reservation:
„
„
„
Stroke volume reservation：
„
End diastolic volume: 15ml
„
End systolic volume: 35~40ml
HR reservation: 2~2.5 times
Hear diseases (heart failure) ——mobilization of cardiac
reservation
2014-04-21
生理与病理生理学系
38
Factors that influence cardiac output
Cardiac output = Stroke volume × HR
Stroke volume
1.
2.
„
Preload ——(前负荷)
„
Afterload ——(后负荷)
„
Contractility of cardiac muscle
Heart rate
2014-04-21
生理与病理生理学系
39
„
Preload↑——initial length ↑—
—end diastolic volume ↑ ——
end diastolic pressure↑
„
Compliance （顺应性）of ventricle
Intraventricular pressure (mmHg)
Influence of CO by preload
Low C
Normal C
High C
Ventricular volume
Compliance curve
2014-04-21
生理与病理生理学系
40
Influence of CO by preload
„
Ventricular functional curve
„
Normal state: 5 ~ 6 mmHg
„
12 ~ 15 mmHg: optimal preload
„
15 ~ 20 mmHg: flat on work output
„
>20 mmHg: no obvious decline
Frank-Starling mechanism——intrinsic
Stroke work of LV
„
NE group
Normal C
Heart failure
ability increase following inflow increase
LV end diastolic P (mm H2O)
Ventricular functional curve
2014-04-21
生理与病理生理学系
41
End diastolic volume =
remained blood + inflowing
blood
„
Filling time
„
Venous returning speed
„
Compliance of ventricle
Stroke work of LV
Factors that influence preload
NE group
Normal C
Heart failure
LV end diastolic P (cm H2O)
Ventricular functional curve
2014-04-21
生理与病理生理学系
42
Influence of cardiac out by afterload
„
Afterload——artery pressure
„
Afterload↑——isometric contraction
↑——stroke volume↓
(Recovered in 30 s)
„
Mechanism: Frank-Starling mechanism
„
Longtime increase in afterload——
pathological remodeling
2014-04-21
生理与病理生理学系
43
„
Contractility: Isometric regulation
„
Factors that influence excitation-contraction
coupling
„
NE—β receptor—L-Ca2+ channel opening ↑
„
Caffeine: affinity of troponin to Ca2+
„
Thyroid hormone: ATPase activity on cross
Stroke work of LV
Influence of cardiac output by contractility
NE group
Normal C
Heart failure
LV end diastolic P (cm H2O)
Ventricular functional curve
bridge
2014-04-21
生理与病理生理学系
44
„
HR↑——Cardiac Output↑
„
>170——CO↓ (too short filling
time)
„
<40 ——maximal EDV
Staircase phenomenon:
„
HR↑ ——contractility↑
„
150-180: maximal
2014-04-21
Cardiac output (L/min)
Influence of cardiac output by HR
Brady~ Normal HR
tachycardia
Heart rate (beats/min)
生理与病理生理学系
45
Heart sounds
„
Originally from: closure of valves, vibrations of atrial or ventricular wall,
or arteriole wall, fluid vibration
„
Phonocardiogram:
„
First sound—low pith and long lasting, symbol of systole, closure of AV
valves, vibration of arteriole wall and blood
„
Second sound—high pith and short lasting, symbol of diastole, the aortic and
pulmonary valves close
„
Third sound—rapid filling, oscillation of blood, vibration of valves,
ventricular wall and papillary muscle
„
Fourth sound－atrial sound, inrush of blood into the ventricles during atrial
systole
2014-04-21
生理与病理生理学系
46