Myocardial E-C Coupling MCQ Quiz | Cardiovascular System

Welcome to this specialized quiz on Myocardial Excitation-Contraction (E-C) Coupling, a cornerstone of cardiovascular physiology for MBBS students. This quiz is designed to test your understanding of the intricate sequence of events that translates an electrical action potential into a coordinated mechanical contraction of the heart muscle. You will be challenged on topics including ion channels, calcium-induced calcium release (CICR), sarcoplasmic reticulum function, and the roles of key regulatory proteins. A strong grasp of these concepts is vital for understanding cardiac function in both health and disease. This quiz consists of 25 multiple-choice questions. After submitting, you can review your score and download all questions with their correct answers in a PDF format for future revision.

1. The primary trigger for calcium release from the sarcoplasmic reticulum in cardiac myocytes is:

2. During which phase of the cardiac action potential does the major influx of Ca2+ occur?

3. The ryanodine receptor (RyR2) in cardiac muscle is located on the membrane of the:

4. Which protein is responsible for sequestering Ca2+ within the sarcoplasmic reticulum?

5. The primary mechanism for removing Ca2+ from the cytosol to induce myocardial relaxation is:

6. In its unphosphorylated state, phospholamban has what effect on SERCA2a?

7. Beta-adrenergic stimulation enhances myocardial contractility (inotropy) primarily by:

8. A key difference in E-C coupling between cardiac and skeletal muscle is that cardiac muscle:

9. The therapeutic effect of Digoxin is primarily mediated by:

10. The term ‘lusitropy’ refers to:

11. Which subunit of the troponin complex directly binds to Ca2+ to initiate contraction?

12. The Frank-Starling mechanism is primarily explained at the cellular level by:

13. The stoichiometry of the Na+/Ca2+ exchanger (NCX) in its forward mode is:

14. What is a “calcium spark”?

15. Acidosis negatively impacts cardiac contractility primarily by:

16. The close apposition of a T-tubule with a terminal cisterna of the SR in a cardiac myocyte is called a:

17. Which of the following plays the LEAST significant role in Ca2+ extrusion from the cardiac myocyte cytosol under normal conditions?

18. The force of cardiac contraction is most directly proportional to:

19. In chronic heart failure, the expression and activity of which protein is typically downregulated?

20. The function of T-tubules in cardiac myocytes is to:

21. The binding of Ca2+ to troponin C leads to a conformational change that primarily moves which protein?

22. An increase in heart rate can lead to an increased force of contraction (treppe or staircase phenomenon). This is best explained by:

23. L-type Ca2+ channels are also known as:

24. What is the effect of catecholamines on phospholamban?

25. Termination of the cross-bridge cycle and detachment of myosin from actin requires: