Final answer:
The myocardium is composed of myocardial contractile cells and myocardial conducting cells. The contractile cells are responsible for conducting impulses and contractions, while the conducting cells form the conduction system of the heart.
Step-by-step explanation:
The myocardium is made up of two major types of cells: myocardial contractile cells and myocardial conducting cells. The myocardial contractile cells make up the bulk of the cells in the atria and ventricles and are responsible for conducting impulses and contractions that pump blood through the body.
On the other hand, the myocardial conducting cells form the conduction system of the heart and initiate and propagate the electrical impulses that trigger heart contractions.