Final answer:
The AV node can serve as a secondary pacemaker for the heart in case the SA node fails. The heart's conduction system, including the AV node and Purkinje fibers, allows for backup pacing capabilities. Artificial pacemakers, which can also contain defibrillators, are medical devices implanted to regulate the heart rhythm when natural pacemakers fail.
Step-by-step explanation:
The secondary pacemaker that can serve the heart in case the primary pacemaker fails is the atrioventricular (AV) node. The heart has a natural pacemaking system, which ensures the rhythmic contraction of the heart muscle cells, leading to the pumping of blood throughout the body. The sinoatrial (SA) node, known as the primary pacemaker, is located in the right atrium and initiates the heartbeat by generating electrical impulses. These impulses cause the atria to contract and then travel to the AV node. The AV node acts as a gatekeeper, momentarily delaying the electrical signal before passing it to the ventricles. This delay ensures the atria have enough time to pump blood into the ventricles.
In cases where the SA node is not functioning properly, the AV node can act as a backup pacemaker by taking over the role to generate impulses, although at a slower rate. If both the SA node and AV node fail to regulate the heart's rhythm, the Purkinje fibers within the ventricles can also create impulses, but this usually results in an even slower heart rate. These components of the heart's electrical system exemplify the importance of a secondary pacemaker, as they are essential for maintaining life-sustaining cardiac function.
When arrhythmias become chronic, artificial pacemakers are used to maintain a steady heart rhythm. An artificial pacemaker is a medical device that delivers electrical impulses directly to the heart muscle. It's capable of detecting body movement and adjusting the heart rate during exercise to meet the increased demand for oxygen and blood. Additionally, some pacemakers are equipped with defibrillators to correct life-threatening arrhythmias instantly. Pacemakers utilize RC circuits for timing, ensuring that the electrical signals are delivered at precise intervals.