19.2. Cardiac Muscle and Electrical Activity

Cardia muscle and electrical activity breakdown and explanation

Autorhythmicity

The ability of cardiac muscle to initiate an electrical potential at a fixed rate that spreads rapidly to trigger contractions.

Myocardial Contractile Cells

Cells that constitute 99% of the cardiac muscle, responsible for contractions that pump blood.

Myocardial Conducting Cells

Cells that form the conduction system of the heart, making up 1% of cardiac cells and initiating and propagating action potentials.

Intercalated Disc

A junction between two adjoining cardiac muscle cells that supports synchronized contraction.

Sinoatrial (SA) Node

The pacemaker of the heart located in the right atrium, initiating the normal electrical rhythm of the heart.

Atrioventricular (AV) Node

A specialized cluster of myocardial conducting cells that provides a critical pause before transmitting impulses to the ventricles.

Bachmann’s Bundle

A pathway that conducts electrical impulses directly from the right atrium to the left atrium.

Purkinje Fibers

Myocardial conductive fibers that spread electrical impulses to the contractile cells in the ventricles.

Wave of Depolarization

The electrical event that triggers muscular contraction, beginning in the right atrium and spreading across the heart.

T Tubules

Structures that are half as numerous in cardiac muscle compared to skeletal muscle, involved in transmitting electrical impulses.

Aerobic Respiration

The process primarily used by cardiac muscle to metabolize lipids and carbohydrates for energy.

Spontaneous Depolarization

The movement of sodium ions that leads to cardiac muscle's autoregulated electrical activity.