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Cardiac Anatomy and Physiology Flashcards

7 cards from real CMT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Cardiac Anatomy and Physiology flashcards as text

  1. Which phase of the cardiac action potential corresponds to the plateau and is caused by calcium influx?

    Answer: Phase 2

    Phase 2 is the plateau phase of the ventricular action potential, maintained by slow calcium channel influx balancing potassium efflux, and corresponds to ventricular contraction.

  2. What is the ejection fraction (EF) and what is the normal value?

    Answer: Percentage of ventricular blood ejected per beat; normal 55–70%

    Ejection fraction is the percentage of end-diastolic volume pumped out each beat; a normal EF is 55–70%, and values below 40% suggest significant systolic dysfunction.

  3. The pericardium serves which primary protective function?

    Answer: Encloses and protects the heart, limiting acute overdistension

    The pericardial sac encloses the heart, reduces friction during beating, anchors it in the mediastinum, and limits acute cardiac dilation.

  4. Which part of the cardiac conduction system normally has the slowest conduction velocity?

    Answer: Atrioventricular node

    The AV node has the slowest conduction velocity (~0.05 m/s), creating the physiologic delay that allows atrial contraction to complete before ventricular contraction begins.

  5. The left anterior descending (LAD) artery is most often called the 'widow maker' because it supplies which critical structure?

    Answer: Anterior wall of left ventricle and anterior two-thirds of the interventricular septum

    The LAD supplies the anterior left ventricular wall and the anterior two-thirds of the interventricular septum, representing a large territory whose occlusion causes massive myocardial infarction.

  6. What is 'automaticity' in cardiac physiology?

    Answer: The ability of certain cardiac cells to spontaneously generate action potentials without external stimulation

    Automaticity is the intrinsic property of specialized cardiac pacemaker cells (SA node, AV node, Purkinje fibers) to depolarize spontaneously and initiate heartbeats without nervous system input.

  7. Preload is best defined as:

    Answer: The degree of myocardial fiber stretch at end-diastole, related to venous return

    Preload represents the degree of stretch of ventricular myocardial fibers at the end of diastole, which is directly related to end-diastolic volume and venous return.