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PHYSIOLOGY OF CARDIAC MUSCLE There are three major types of cardiac muscle: atrial muscle, ventricular muscle, and specialized excitatory and conductive muscle fibers cardiac muscle is striated and have actin and myosin filaments that interdigitate and slide along each other during contraction. Ca...

PHYSIOLOGY OF CARDIAC MUSCLE There are three major types of cardiac muscle: atrial muscle, ventricular muscle, and specialized excitatory and conductive muscle fibers cardiac muscle is striated and have actin and myosin filaments that interdigitate and slide along each other during contraction. Cardiac muscle has intercalated discs between cardiac muscle cells that have very low electrical resistance, allowing an action potential to travel rapidly between cardiac muscle cells. The cardiac muscle is a syncytium of many heart muscle cells in which the action potential spreads rapidly from cell to cell. The atrioventricular (A-V) junction slowly conducts impulses from the atria to the ventricles. In normal patients this is an exclusive pathway because the atrial syncytium and ventricular syncytium are normally insulated from one another by fibrous tissue.