Download Cardiac biophysics

Cardiac biophysics
Heart
Pump of the circulatory system
Number of
contractions
Expelled
blood volume
1 min
~70
~6 l
1 day
~100.000
~8600 l
Life
(70 yrs)
~2.5 x 109
~220 x 106 l
Cardiac biophysics
1.
2.
3.
4.
Structure of the heart
Coordinated contraction
Cardiac cycle
Work of the heart
Structure of the human heart
Aorta
A. pulmonalis
Left atrium
Bulbus
aortae
Aorta
valve
Mitral
(bicuspid)
valve
Right atrium
Tricuspid
valve
Left ventricle
Right ventricle
Septum
Functional structure of the heart
myocyte
Structural and
functional unit:
sarcomere
Titin
Z-line
(spring function)
Thin
filament
(actin)
M-line
Thick
filament
(myosin)
Z-line
Activation of coordinated
contractions
Sinus node
EKG
mV
mm
R
AV node
(Tawara-Aschoff)
10 mm (1 mV)
His-bundle
T
P
0,08 s
Tawara-bundles
0,15 s
Purkinjefibers
3.5
mm
Q
S
0,08 s
ST
t (s)
The cardiac cycle
Contraction (systole) - relaxation (diastole) cycle of the heart
systole
diastole
atrium
0,1 s
0,7 s
ventricle
0,3 s
0,5 s
Beats per minute (1/min)
Events of the cardiac cycle
1-2: pre-ejection period (PEP) 2-3: ejection period (EP) 3-4: isovolumetric relaxation (IVR) 4-1: ventricular filling (VF)
Aorta
Pressure
Left ventricle
1-3: ventricular systole
3-1: ventricular diastole
Flow
Intensity
Bulbus aortae
A. pulmonalis
Pressure
Right ventricle
Semilunar valve
Atrioventricular valve
Time
Pressure-volume diagram of left ventricle
Mm=Isovolumetric
Pressure maximum
Mb=Isobaric
Volume minimum
R=Relaxed ventricle
EP
IVR
PEP
VF
Residual
volume
Stroke
volume
Work of the heart
(work of left ventricle)
P (kPa)
16
Indicator diagram:
EP
10,6
Simplified pressurevolume relationship
IVR
PEP
VF
0
50
1 2
L  pV  mv
2
L
130
V (ml)
pV=static (volumetric) component
1/2mv2=dynamic component
p=pressure
V=stroke volume
1
2
13,3103 N /m 2  0,08103 m 3  0,08kg 1m /s 1,06Nm  0,04Nm 1,1J
2
Adjustment of stroke volume
Frank-Starling mechanism
Work of heart
against increased
presssure
Compensatitory
increase in
stroke volume
Cardiac biophysics
1.
2.
3.
4.
Structure of the heart
Coordinated contraction
Cardiac cycle
Work of the heart