The heart’s role in the cardiovascular system is to ensure the uninterrupted circulation of blood in the body. Blood contains oxygen and nutrients that must be distributed throughout the body, and it carries waste away from the tissues for excretion.
Two processes within the heart ensure that blood circulates efficiently. The mechanical system is the driving force behind blood circulation, and the electrical system acts as a switch that tells the heart when and how to pump blood. Without electrical stimuli, the heart cells would not contract.
The heart’s mechanical system can be assessed for adequate pumping by measuring blood pressure and palpating peripheral pulses. The electrical impulses of the heart are measured using an electrocardiogram (ECG).
Electrocardiology is concerned with understanding the electrical activity of the heart. The heart’s electrical conduction system generates and transmits impulses that coordinate its wall motion. Effective cardiac output is a result of coordinated cardiac motion.
During normal function, an electrical impulse is generated from the sinus cells of the sinoatrial (SA) node and travels through the conduction cells to elicit an action potential. The similarity in action potentials between the sinus node cell and conduction cells is why impulses can occur outside the pacemaker sites and cause an arrhythmia or a dysrhythmia.