A client is admitted with a diagnosis of heart block. The nurse is aware that the pacemaker of the heart is the: A. AV node B. Purkinje fibers C. SA node D. Bundle of His

To answer this question, we need to know about the conduction system of the heart. The heart's electrical conduction system controls the coordinated contraction of the heart's chambers (atria and ventricles) through the generation and propagation of electrical impulses. The main components of the conduction system are: 1. Sinoatrial (SA) node 2. Atrioventricular (AV) node 3. Bundle of His 4. Purkinje fibers

Next, let's review the function of each component: 1. SA node: It is located in the right atrium and generates the electrical impulses that initiate the contraction of the atria, known as the heartbeat. It is often referred to as the "natural pacemaker" of the heart. 2. AV node: Located at the border of the right atrium and ventricle, the AV node receives the electrical impulses from the SA node and sends them further to the Bundle of His to allow synchronized contraction of the ventricles. 3. Bundle of His: This is a bundle of specialized muscle fibers that carry electrical impulses from the AV node to the Purkinje fibers in the ventricles. 4. Purkinje fibers: These fibers receive electrical impulses from the Bundle of His and spread them throughout the ventricular muscle, causing the ventricles to contract.

As mentioned earlier, the SA node is responsible for initiating the electrical impulses that trigger the heart's contractions. It is the primary pacemaker of the heart because it is the component that generates the rhythmical electrical activity. So, the correct answer is: C. SA node