Atrioventricular node

Definition

The atrioventricular node (AV node) is a specialized cluster of cells located in the heart's right atrium that plays a crucial role in coordinating the electrical signals that regulate heartbeats. It acts as a gatekeeper between the atria and ventricles, ensuring that the electrical impulses generated by the sinoatrial node are transmitted efficiently, allowing for proper timing of contraction between the upper and lower chambers of the heart.

5 Must Know Facts For Your Next Test

1. The AV node is located at the junction of the atria and ventricles, specifically at the lower part of the right atrium near the interatrial septum.
2. It has a slower conduction velocity compared to other parts of the heart's conduction system, allowing it to delay the electrical signal before passing it to the ventricles.
3. This delay is crucial for ensuring that the atria contract and empty their blood into the ventricles before the ventricles contract.
4. If the SA node fails to function properly, the AV node can take over as a backup pacemaker, though at a slower rate.
5. The AV node plays a vital role in preventing rapid firing from the atria from overwhelming the ventricles, thereby protecting against potential arrhythmias.

Review Questions

• How does the atrioventricular node function in relation to the sinoatrial node and its role in heart rhythm?
  • The atrioventricular node works closely with the sinoatrial node to maintain a proper heart rhythm. The SA node generates electrical impulses that trigger each heartbeat, while the AV node receives these impulses and introduces a delay before transmitting them to the ventricles. This ensures that the atria contract first, allowing for effective blood flow into the ventricles before they contract. Without this coordination, heart function would be less efficient.
• Discuss the importance of the delay introduced by the AV node in terms of cardiac function and blood flow.
  • The delay introduced by the AV node is critical for optimal cardiac function because it allows sufficient time for the atria to fully contract and push blood into the ventricles. This timing ensures that when the ventricles contract, they are adequately filled with blood, maximizing cardiac output. If this delay were absent or significantly shortened, it could lead to inefficient blood flow and reduced overall heart performance, potentially resulting in clinical complications.
• Evaluate how disruptions in AV node function can impact overall cardiovascular health and what conditions might arise as a result.
  • Disruptions in AV node function can lead to various cardiovascular conditions, including complete heart block or arrhythmias. When impulses from the atria are not properly transmitted to the ventricles, it can result in irregular heartbeats or bradycardia. These conditions can significantly impair blood circulation, leading to symptoms such as fatigue, dizziness, or fainting spells. In severe cases, treatment may involve medical intervention such as pacemaker implantation to restore proper electrical conduction within the heart.

Related terms

sinoatrial node: The sinoatrial node (SA node) is known as the heart's natural pacemaker, generating electrical impulses that initiate each heartbeat.

bundle of His: The bundle of His is a collection of heart muscle cells that transmit electrical impulses from the AV node to the ventricles, facilitating coordinated contraction.

electrophysiology: Electrophysiology is the study of the electrical properties and activities of biological cells and tissues, essential for understanding how signals propagate in the heart.