Emergency Medical Technician (EMT) Intermediate Practice Exam

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Prepare for your EMT Intermediate Test. Study with detailed flashcards and multiple-choice questions, each featuring hints and explanations. Ace your exam!

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What type of valves are the aortic and pulmonic valves classified as?

Atrioventricular
Semilunar
Tricuspid
Mitral

The correct answer is: Semilunar

The aortic and pulmonic valves are classified as semilunar valves. This classification is based on their anatomical structure and functional role within the heart. Semilunar valves are located at the exit points of the ventricles, specifically at the aorta and pulmonary artery, and they prevent the backflow of blood into the ventricles after it has been ejected during contraction (systole). Semilunar valves each have three cusps that are shaped like half-moons (hence the name "semilunar"). During ventricular contraction, these valves open to allow blood to flow out of the heart. Once ventricular pressure falls and the heart relaxes (diastole), the valves close to prevent any blood from flowing back into the ventricles. In contrast, atrioventricular valves, which include the tricuspid and mitral valves, are found between the atria and ventricles and serve a different function by preventing backflow of blood into the atria during ventricular contraction. This distinction is crucial for understanding the different roles and locations of the heart's valves in the circulatory system.