Chapter 19 - Section 19.3 - Study Guide - Assess Your Learning Outcomes - Page 740: 3

The cardiac conduction system is a network of specialized cardiac muscle cells that initiate and propagate electrical impulses throughout the heart, coordinating its rhythmic contractions. These impulses ensure that the heart chambers contract in a synchronized and coordinated manner, enabling efficient pumping of blood. Here are the key components of the cardiac conduction system and the path traveled by electrical signals through the heart: **Components of the Cardiac Conduction System:** 1. **Sinoatrial (SA) Node:** - Located in the upper wall of the right atrium near the entrance of the superior vena cava. - Often referred to as the heart's natural pacemaker. - Generates electrical impulses spontaneously, initiating each heartbeat. - Impulses from the SA node spread through both atria, causing them to contract simultaneously. 2. **Atrioventricular (AV) Node:** - Located at the junction between the atria and ventricles, near the interatrial septum. - Delays the electrical impulse slightly to allow the atria to fully contract and fill the ventricles with blood. - After the delay, the impulse is conducted to the ventricles through specialized fibers known as the bundle of His. 3. **Bundle of His:** - A specialized bundle of conducting fibers that extends from the AV node along the interventricular septum. - Divides into two branches, the right bundle branch and the left bundle branch, to conduct impulses to both ventricles. 4. **Purkinje Fibers:** - Thin, specialized fibers that spread throughout the ventricles, originating from the bundle branches. - Rapidly conduct electrical impulses to the ventricular muscle cells. - Coordinate the synchronous contraction of the ventricles, starting from the apex and moving toward the base. **Path of Electrical Signals Through the Heart:** 1. The electrical impulse originates in the SA node, generating an action potential that causes the atria to contract. 2. The impulse travels from the SA node through the atria, reaching the AV node. 3. The AV node delays the impulse slightly, allowing the atria to contract and pump blood into the ventricles. 4. After the delay, the impulse travels down the bundle of His in the interventricular septum. 5. The bundle of His branches into the right and left bundle branches, carrying the impulse toward the apex of the heart. 6. The impulse then spreads rapidly through the Purkinje fibers, causing the ventricles to contract from the bottom (apex) to the top (base), pushing blood out of the heart. The coordinated propagation of electrical signals through the cardiac conduction system ensures that the heart chambers contract in a synchronized sequence, facilitating effective pumping of blood. This coordinated contraction is essential for maintaining efficient circulation and proper functioning of the cardiovascular system.

The cardiac conduction system is a network of specialized cardiac muscle cells that initiate and propagate electrical impulses throughout the heart, coordinating its rhythmic contractions. These impulses ensure that the heart chambers contract in a synchronized and coordinated manner, enabling efficient pumping of blood. Here are the key components of the cardiac conduction system and the path traveled by electrical signals through the heart: **Components of the Cardiac Conduction System:** 1. **Sinoatrial (SA) Node:** - Located in the upper wall of the right atrium near the entrance of the superior vena cava. - Often referred to as the heart's natural pacemaker. - Generates electrical impulses spontaneously, initiating each heartbeat. - Impulses from the SA node spread through both atria, causing them to contract simultaneously. 2. **Atrioventricular (AV) Node:** - Located at the junction between the atria and ventricles, near the interatrial septum. - Delays the electrical impulse slightly to allow the atria to fully contract and fill the ventricles with blood. - After the delay, the impulse is conducted to the ventricles through specialized fibers known as the bundle of His. 3. **Bundle of His:** - A specialized bundle of conducting fibers that extends from the AV node along the interventricular septum. - Divides into two branches, the right bundle branch and the left bundle branch, to conduct impulses to both ventricles. 4. **Purkinje Fibers:** - Thin, specialized fibers that spread throughout the ventricles, originating from the bundle branches. - Rapidly conduct electrical impulses to the ventricular muscle cells. - Coordinate the synchronous contraction of the ventricles, starting from the apex and moving toward the base. **Path of Electrical Signals Through the Heart:** 1. The electrical impulse originates in the SA node, generating an action potential that causes the atria to contract. 2. The impulse travels from the SA node through the atria, reaching the AV node. 3. The AV node delays the impulse slightly, allowing the atria to contract and pump blood into the ventricles. 4. After the delay, the impulse travels down the bundle of His in the interventricular septum. 5. The bundle of His branches into the right and left bundle branches, carrying the impulse toward the apex of the heart. 6. The impulse then spreads rapidly through the Purkinje fibers, causing the ventricles to contract from the bottom (apex) to the top (base), pushing blood out of the heart. The coordinated propagation of electrical signals through the cardiac conduction system ensures that the heart chambers contract in a synchronized sequence, facilitating effective pumping of blood. This coordinated contraction is essential for maintaining efficient circulation and proper functioning of the cardiovascular system.