Final answer:
The heart is autorhythmic with specialized cells called pacemaker cells responsible for generating and controlling its contractions. These pacemaker cells can depolarize and generate action potentials on their own, and they are connected to other cardiac muscle fibers to coordinate the heart's contractions.
Step-by-step explanation:
The heart is autorhythmic, which means it has the ability to generate its own electrical impulses and contract rhythmically without any external control. This is possible due to specialized cells called pacemaker cells, which are responsible for initiating and controlling the heart's contractions. The pacemaker cells are located in the sinoatrial node and generate electrical signals that spread to the rest of the heart, coordinating its contractions.
These pacemaker cells are different from other cardiac muscle cells in several ways. They are self-excitable, meaning they can depolarize and generate action potentials on their own. They have the ability to undergo spontaneous depolarization due to the presence of ion channels that allow the flow of sodium and potassium ions.
This spontaneous depolarization occurs at regular intervals, determining the heart rate. Additionally, pacemaker cells are connected to surrounding muscle fibers and specialized fibers of the heart's conduction system through gap junctions, allowing for the transmission of electrical signals and coordinated contraction of the heart.