Which heart sound corresponds to the closure of the atrioventricular (AV) valves?
S1
S4
S2
S3
The Correct Answer is A
A. S1:
S1 is produced by the closure of the mitral and tricuspid valves at the beginning of systole. It signals the start of ventricular contraction and is best heard at the apex for the mitral valve and lower left sternal border for the tricuspid valve.
B. S4:
S4 occurs during atrial contraction in late diastole and may indicate a stiff or hypertrophic ventricle; it is not related to AV valve closure.
C. S2:
S2 occurs with the closure of semilunar valves (aortic and pulmonic) at the end of systole, marking the beginning of diastole.
D. S3:
S3 occurs during rapid ventricular filling in early diastole and may indicate volume overload; it does not correspond to AV valve closure.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Supplies the lateral wall of the left ventricle:
The circumflex artery branches from the left coronary artery and supplies the lateral and posterior walls of the left ventricle as well as part of the left atrium. This supply is crucial for maintaining effective left ventricular contraction and overall cardiac output.
B. Supplies the right ventricle:
The right ventricle is primarily supplied by the right coronary artery, not the circumflex artery. Misidentifying this can affect understanding of infarct locations.
C. Supplies the interventricular septum:
The interventricular septum is mainly supplied by the LAD artery, which is critical for coordinating left ventricular contraction.
D. Supplies the right atrium:
The right atrium is primarily supplied by the RCA, not the circumflex artery. Understanding arterial supply is important for predicting conduction system involvement in MI.
Correct Answer is D
Explanation
A. Circumflex artery:
The circumflex artery primarily supplies the lateral and posterior walls of the left ventricle and the left atrium. While occlusion can cause MI, it is less commonly involved than the LAD because it supplies a smaller portion of the myocardium in most individuals.
B. Right coronary artery:
The RCA supplies the right atrium, right ventricle, inferior left ventricle, and parts of the conduction system. While it can cause inferior MI when occluded, it is not the artery most frequently associated with large anterior infarctions.
C. Posterior descending artery:
The posterior descending artery (PDA) is a branch of either the RCA or circumflex depending on dominance. It supplies the inferior septum, but infarctions here are usually smaller than those caused by LAD occlusion.
D. Left anterior descending artery:
The LAD artery supplies the anterior wall of the left ventricle and the interventricular septum, which are critical for left ventricular contraction. Occlusion of the LAD is often called a “widowmaker MI” because it affects a large portion of the myocardium and is associated with high mortality.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.