Question 1

Which event immediately follows ventricular depolarization as seen on the ECG QRS complex?

Accepted Answer

Ventricular contraction

Question 2

During which phase of the cardiac cycle does ventricular pressure exceed aortic pressure, resulting in blood ejection?

Accepted Answer

Ventricular ejection

Question 3

What is the primary role of Ca$$^{2+} in $$excitation-contraction coupling in cardiac contractile cells?

Accepted Answer

Ca$$^{2+}$$ binds to troponin, allowing myosin to bind to actin

Question 4

A patient presents with a heart murmur during systole. Which valve abnormality is most likely responsible?

Accepted Answer

Mitral regurgitation

Question 5

Which equation best describes the relationship between pressure, flow, and resistance in the heart?

Accepted Answer

$$P = F 	imes R$$

Question 6

What mechanical event occurs immediately after the T wave on an ECG?

Accepted Answer

Ventricular relaxation

Question 7

Which of the following best explains why electrical events precede mechanical events in the cardiac cycle?

Accepted Answer

Depolarization triggers Ca$$^{2+}$$ release, leading to contraction

Question 8

In mitral stenosis, which of the following changes is most likely to occur?

Accepted Answer

Increased resistance from left atrium to left ventricle

Question 9

Which step in excitation-contraction coupling is directly responsible for relaxation of cardiac muscle?

Accepted Answer

Pumping Ca$$^{2+}$$ back into the sarcoplasmic reticulum

Question 10

During isovolumic contraction, which of the following is true regarding pressures in the left heart?

Accepted Answer

Left atrial pressure \u003c left ventricular pressure \u003c aortic pressure

Question 11

Which of the following best describes the sequence of events in cardiac excitation-contraction coupling?

Accepted Answer

Action potential → Ca$$^{2+}$$ influx → Ca$$^{2+}$$ release from SR → Ca$$^{2+}$$ binds troponin → contraction

Question 12

A patient with aortic stenosis is most likely to experience which of the following?

Accepted Answer

Increased velocity and turbulent flow during systole

Question 13

Which of the following is the correct order of mechanical events in the cardiac cycle?

Accepted Answer

Isovolumic contraction → ventricular ejection → isovolumic relaxation → ventricular diastole

Question 14

Which of the following best explains the presence of a heart murmur in a patient with an incompetent valve?

Accepted Answer

Turbulent flow occurs when the valve should be closed

Question 15

Which of the following statements about the timing of cardiac events is correct?

Accepted Answer

Electrical depolarization precedes mechanical contraction

Question 16

If the P wave on an ECG is absent, which mechanical event is most likely to be affected?

Accepted Answer

Atrial contraction

Question 17

Which of the following best describes the effect of increased resistance due to valve stenosis?

Accepted Answer

Increased velocity of blood flow and turbulent flow

Question 18

Which process is responsible for the removal of Ca$$^{2+}$$ from the cytoplasm during cardiac muscle relaxation?

Accepted Answer

Active transport into the sarcoplasmic reticulum by Ca$$^{2+}-$$ATPase

Question 19

A patient with mitral regurgitation will most likely have which of the following findings?

Accepted Answer

Backward flow of blood into the left atrium during ventricular contraction

Question 20

Which of the following is true regarding the relationship between depolarization and contraction in cardiac muscle?

Accepted Answer

Depolarization triggers contraction via excitation-contraction coupling

Mechanical Activity of the Heart: Excitation-Contraction Coupling, Cardiac Cycle, and Pathological Alterations

Study Guide - Practice Questions