How does the coronary artery supply affect the function of the heart's conduction system?
The circumflex artery supplies the atrioventricular node
The left anterior descending artery supplies the sinoatrial node
The left coronary artery supplies the sinoatrial node
The right coronary artery supplies the sinoatrial and atrioventricular nodes
The Correct Answer is D
A. The circumflex artery supplies the atrioventricular node:
In most individuals, the AV node is supplied by the right coronary artery, not the circumflex. The circumflex supplies the lateral and posterior walls of the left ventricle.
B. The left anterior descending artery supplies the sinoatrial node:
The LAD primarily supplies the anterior wall of the left ventricle and the interventricular septum, not the SA node.
C. The left coronary artery supplies the sinoatrial node:
The left coronary artery branches into the LAD and circumflex, which supply the left ventricle and parts of the atrium, but the SA node is usually supplied by the right coronary artery in about 60% of people.
D. The right coronary artery supplies the sinoatrial and atrioventricular nodes:
The RCA commonly supplies the SA node (~60% of people) and the AV node (~85% of people), which are crucial for initiating and coordinating the heartbeat. Occlusion of the RCA can cause arrhythmias or conduction blocks.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. Increase cardiac output by stretching the ventricles:
Stretching of the ventricles relates to preload, but papillary muscles and chordae tendineae do not directly stretch the ventricles to increase output.
B. Facilitate rapid conduction of electrical impulses:
Electrical conduction is carried by the SA node, AV node, bundle of His, and Purkinje fibers, not the papillary muscles or chordae tendineae.
C. Assist in opening the semilunar valves:
Semilunar valves (aortic and pulmonic) open due to ventricular pressure exceeding arterial pressure, not through papillary muscle function.
D. Prevent valve prolapse during ventricular contraction:
The papillary muscles contract during ventricular systole, pulling on the chordae tendineae, which anchor the mitral and tricuspid valves. This prevents backflow of blood into the atria (valve prolapse) and ensures efficient unidirectional flow.
Correct Answer is D
Explanation
A. Between the left ventricle and aorta; prevents backflow of blood into the left ventricle:
This describes the aortic valve, not the mitral valve. The aortic valve prevents backflow from the aorta into the left ventricle. Confusing these can lead to misinterpretation of murmurs or heart sounds.
B. Between the right atrium and right ventricle; prevents backflow of blood into the right atrium:
This describes the tricuspid valve, which is on the right side of the heart. The mitral valve is on the left side.
C. Between the right ventricle and pulmonary artery; prevents backflow of blood into the right ventricle:
This describes the pulmonic valve, which is located at the right ventricular outflow tract, not the mitral valve.
D. Between the left atrium and left ventricle; prevents backflow of blood into the left atrium:
The mitral valve (also called the bicuspid valve) is located between the left atrium and left ventricle. Its primary function is to allow unidirectional blood flow into the left ventricle during diastole and prevent regurgitation into the left atrium during systole, maintaining efficient cardiac output.
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