Properties of Cardiac Muscle

Practice vocabulary flashcards covering the structural characteristics, properties, rhythmicity rates, and action potentials of cardiac muscle from Chapter 31.

Dark bands

Thick protein filaments observed under the microscope in striated cardiac muscle fibres that are made of myosin proteins.

Thin filaments

Filaments in striated cardiac muscle fibres that are made of actin protein.

Cardiac myosin

A hexamer consisting of two myosin heavy chains (MHC), each associated with two myosin light chains (MLC), which modulates cross-bridge kinetics to produce contraction.

Rhythmicity

The inherent property of cardiac muscle to be self-excitable and initiate its own impulse rhythmically.

SA node rhythmicity rate

$70\text{ to }80\text{ per minute}$.

AV node rhythmicity rate

$40\text{ to }60\text{ per minute}$.

Atrial rhythmicity rate

$60\text{ per minute}$.

Ventricular rhythmicity rate

$20\text{ to }40\text{ per minute}$.

Fast action potentials

Action potentials occurring in atrial and ventricular muscles and Purkinje fibres, characterized by a true resting potential, a fast depolarization phase, and a prolonged plateau phase.

Slow response action potentials

Action potentials occurring in the sino-atrial node and atrioventricular (AV) node.

Phase 0

The phase characterized by rapid depolarization and overshoot, caused by the hundred-fold opening of voltage-gated sodium channels.