Describe how heart contraction and relaxation influence coronary blood flow
Name the major branches of the coronary arteries, and note the heart regions served by each

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Understand that coronary blood flow is influenced by the phases of the cardiac cycle: systole (heart contraction) and diastole (heart relaxation). During systole, the myocardium contracts, compressing the coronary vessels and reducing blood flow, especially in the subendocardial regions.

During diastole, the heart muscle relaxes, relieving pressure on the coronary vessels and allowing blood to flow more freely through the coronary arteries. This phase is critical because most coronary perfusion occurs during diastole.

Identify the major branches of the coronary arteries starting with the left coronary artery (LCA), which typically divides into the left anterior descending artery (LAD) and the circumflex artery (LCx).

Note that the LAD supplies the anterior wall of the left ventricle, the anterior two-thirds of the interventricular septum, and the apex of the heart, while the circumflex artery supplies the lateral and posterior walls of the left ventricle.

Recognize the right coronary artery (RCA) as the other major branch, which supplies the right atrium, right ventricle, the posterior one-third of the interventricular septum, and often the sinoatrial (SA) and atrioventricular (AV) nodes, important for cardiac conduction.

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Cardiac Cycle and Coronary Blood Flow

The cardiac cycle consists of systole (contraction) and diastole (relaxation). Coronary blood flow primarily occurs during diastole because the heart muscle relaxes, reducing pressure on coronary vessels and allowing blood to perfuse the myocardium. During systole, contraction compresses coronary vessels, limiting blood flow.

Major Coronary Arteries

The two main coronary arteries are the left and right coronary arteries. The left coronary artery branches into the left anterior descending (LAD) and circumflex arteries, while the right coronary artery (RCA) supplies other regions. These arteries deliver oxygenated blood to specific heart areas.

Regions Supplied by Coronary Artery Branches

The LAD artery supplies the anterior wall of the left ventricle and the interventricular septum. The circumflex artery supplies the lateral and posterior walls of the left ventricle. The RCA supplies the right atrium, right ventricle, and parts of the posterior left ventricle and conduction system.

Describe how heart contraction and relaxation influence coronary blood flowName the major branches of the coronary arteries, and note the heart regions served by each