Final answer:
Myocardial conducting cells initiate the electrical impulses that trigger heart contractions, setting the heart rate and ensuring coordinated contractions. Along with myocardial contractile cells, they play essential roles in the heart's conduction system and the pumping of blood.
Step-by-step explanation:
The myocardial conducting cells initiate and propagate the action potential (the electrical impulse) that travels throughout the heart and triggers the contractions that propel the blood. There are two major types of cardiac muscle cells: myocardial contractile cells and myocardial conducting cells. The myocardial contractile cells make up 99 percent of the cells in the atria and ventricles, and are responsible for the muscle contractions that pump blood through the body.
Purkinje cells, which are part of the conducting cells, differ from contractile cells as they are smaller and have fewer myofibrils, reflecting their specialized function over muscle contraction. The autorhythmicity of pacemaker cells, such as those found in the sinoatrial (SA) node, is crucial for setting the heart rate and ensuring coordinated contractions across the heart's muscular system, referred to as a functional syncytium.
The complete sequence of heart muscle activation begins with the SA node and proceeds through the internodal pathways, atrioventricular (AV) node, AV bundle of His, bundle branches, and finally, the Purkinje fibers. This process is critical for the proper functioning of the heart as it pumps blood, which is why understanding the structure and function of cardiac muscle cells is vital in the field of medicine.