78
Dynamics
of
the
Vascular System
4.1.2
Dynamics
of
Cardiac Muscle Contraction and Force-Length-
Velocity Relations
Muscle
fiber
c
.
'8
'.
I
Z
I
8
'.
Contracted
Fig.
4.1.2:
Illustration
of
the role
of
the sliding filament hypothesis. The overlap of actin
and myosin gives rise to contraction. A-band, H-zone and Z-line are shown. From
Rushmer
(1972).
Sarcomeres
are the
fundamental
building
blocks
of the
myocardium. They exhibit the ability to change length, generate force
and govern overall ventricular contraction. Within the sarcomere, there
are thick and thin filaments. These are the actin and myosin molecules.
The overlapping and relative positions of these filaments determine the
changes in force development. The "sliding filament hypothesis" as it is
called formed the original basis for the understanding of the contraction
process in striated muscle. The tension initially increases with increasing
