Final answer:
Contractile cells are responsible for the heart's pumping function and have a stable resting phase, whereas autorhythmic cells are self-excitable, initiate the heart's rhythm, and coordinate contractions through the functional syncytium.
Step-by-step explanation:
Difference Between Contractile and Autorhythmic Cells
The heart is comprised of two distinct types of cardiac muscle cells: myocardial contractile cells and myocardial conducting cells, also known as autorhythmic cells. Contractile cells are responsible for the contraction that pumps blood through the body and demonstrate a stable resting phase of approximately -80 mV for cells in the atria and -90 mV for cells in the ventricles. They respond to stimulation by voltage-gated mechanisms.
Autorhythmic cells, on the other hand, possess the unique property of autorhythmicity, meaning they can initiate and fire action potentials independently at set intervals to determine the heart rate. These cells, including pacemaker cells, spontaneously depolarize to threshold and are interconnected with gap junctions, which allow them to synchronize contractions throughout the heart muscle effectively, functioning as a functional syncytium.
While contractile cells have an action potential with an extended plateau phase for effective pumping action, autorhythmic cells have a different action potential profile necessary for establishing the heart's rhythm, ensuring the coordinated sequence of heart muscle contractions.