Smooth & Cardiac Muscle Physiology — Nerve & Muscle Physiology

Smooth & Cardiac Muscle Physiology MCQs: practice questions

Sample Smooth & Cardiac Muscle Physiology multiple-choice questions from Nerve & Muscle Physiology.

1. Intercalated discs contain structures that help cardiac muscle cells:

   • A. Detach from one another
   • B. Prevent all ion movement
   • C. Mechanically and electrically couple
   • D. Store neurotransmitter
   • E. Destroy Ca2+

2. Which autonomic neurotransmitter commonly relaxes vascular smooth muscle through nitric oxide signaling?

   • A. GABA
   • B. Acetylcholine indirectly via endothelium
   • C. Glutamate
   • D. Dopamine only
   • E. Glycine

3. The long cardiac action-potential plateau is maintained largely by:

   • A. Na+–K+ pump reversal
   • B. Only K+ influx
   • C. Cl− entry
   • D. Sustained inward Ca2+ current
   • E. ATP diffusion

4. Compared with skeletal muscle, cardiac muscle has a much longer:

   • A. Sarcomere
   • B. Actin filament
   • C. Myosin head
   • D. T-tubule only
   • E. Action-potential duration and refractory period

5. A rise in intracellular Ca2+ in smooth muscle leads to contraction by increasing:

   • A. Acetylcholinesterase activity
   • B. Troponin C phosphorylation
   • C. Myosin light-chain phosphorylation
   • D. Na+–K+ ATPase activity only
   • E. Actin degradation

6. Cardiac muscle cells are electrically coupled mainly through:

7. Cardiac muscle contraction is initiated by Ca2+ binding to:

8. Which muscle type is under involuntary autonomic and hormonal regulation and lacks troponin?

9. Parasympathetic stimulation of the SA node generally:

10. The Ca2+–calmodulin complex activates smooth-muscle:

11. The prolonged cardiac refractory period prevents:

12. Smooth muscle can maintain tone even when:

13. A distinctive feature of cardiac muscle excitation–contraction coupling is:

14. A rise in intracellular Ca2+ in cardiac muscle leads to contraction by increasing:

15. Which statement best compares excitation–contraction coupling in skeletal and cardiac muscle?

16. Smooth muscle contraction can be maintained with relatively low ATP consumption because of the:

17. If cardiac muscle could undergo tetanus like skeletal muscle, the major physiologic problem would be:

18. A positive chronotropic effect means an increase in:

19. Sympathetic stimulation of the heart generally:

20. Nitric oxide relaxes vascular smooth muscle primarily by increasing:

21. Smooth muscle cells can contract in response to stretch through:

22. The major intracellular event promoting smooth-muscle relaxation is a decrease in:

23. Unlike skeletal muscle, smooth muscle contraction is regulated primarily by Ca2+ binding to:

24. Which muscle type has striations but is involuntary?

25. The cardiac contractile force increases when more Ca2+ becomes available to:

26. A positive inotropic effect means an increase in:

27. The sinoatrial node normally acts as the cardiac pacemaker because it has:

28. Which feature distinguishes smooth muscle from skeletal muscle?

29. A drug that inhibits myosin light-chain kinase in smooth muscle would most directly:

30. Autonomic stimulation can alter heart rate primarily by changing: