What is the Difference Between Contractile Myocardium and Autorhythmic Myocardium?

Contractile myocardium and autorhythmic myocardium are two types of cardiac muscle cells that play different roles in the heart. The main differences between them are:

1. Function: Contractile myocardium constitutes 99% of the heart cells and is responsible for the strong, synchronized contractions necessary to pump blood through the body. Autorhythmic myocardium, on the other hand, constitutes only 1% of the heart cells and serves as a pacemaker to initiate the cardiac cycle.
2. Action Potentials: In contractile myocardium, the action potential results from the inward flow of sodium ions, while in autorhythmic myocardium, the action potential is caused by the inward flow of calcium ions.
3. Location: Autorhythmic cells are concentrated in specific areas, such as the sinoatrial (SA) node, the atrioventricular (AV) node, and the atrioventricular bundle (bundle of His). Contractile myocardium cells are found in the atria and ventricles.
4. Size: Myocardial conducting cells (autorhythmic) are generally much smaller than the contractile cells and have fewer myofibrils or other organelles.

Comparative Table: Contractile Myocardium vs Autorhythmic Myocardium

Contractile myocardium and autorhythmic myocardium are two types of cardiac muscle cells that serve different functions in the heart. Here is a table comparing their differences:

Contractile myocardium constitutes the bulk of cells in the atria and ventricles and is responsible for the contractions that pump blood through the body. On the other hand, autorhythmic myocardium is a type of cardiac muscle that serves as a pacemaker to initiate the electrical impulses that trigger the mechanical activity of the heart. Autorhythmic cells are concentrated in the areas of the sinoatrial node, atrioventricular node, and other specialized areas.