The ______is the primary pacemaker of the heart.


a. atrioventricular node
b. sinoatrial node
c. Purkinje fiber system
d. atrioventricular bundle

Verified step by step guidance

1. Identify the role of a pacemaker in the heart, which is to initiate and regulate the heartbeat.
2. Understand that the primary pacemaker is responsible for setting the pace of the heart's rhythm.
3. Recall the anatomical location and function of each option: the atrioventricular node, sinoatrial node, Purkinje fiber system, and atrioventricular bundle.
4. Recognize that the sinoatrial node is located in the right atrium and is known for its role in initiating the heartbeat.
5. Conclude that the sinoatrial node is commonly referred to as the primary pacemaker of the heart.

Key Concepts

Sinoatrial Node

The sinoatrial (SA) node is a specialized group of cells located in the right atrium of the heart. It is known as the primary pacemaker because it generates electrical impulses that initiate the heartbeat, setting the rhythm for the entire heart. The SA node's activity is influenced by the autonomic nervous system, which adjusts heart rate according to the body's needs.

Atrioventricular Node

The atrioventricular (AV) node is another critical component of the heart's electrical conduction system, located between the atria and ventricles. It serves as a gatekeeper, receiving impulses from the SA node and delaying them slightly before passing them to the ventricles. This delay allows the atria to contract and fill the ventricles with blood before they contract, ensuring efficient blood flow.

Electrical Conduction System

The electrical conduction system of the heart includes structures such as the SA node, AV node, bundle of His, and Purkinje fibers. This system coordinates the heart's contractions by transmitting electrical signals throughout the heart muscle. Understanding this system is essential for comprehending how the heart maintains a regular rhythm and responds to physiological demands.