Muscle Physiology and Contraction Practice Questions
20 free Muscle Physiology and Contraction practice questions for the USMLE Step 1, each with the correct answer and a detailed explanation. Open any question below, or take the full set as an interactive quiz.
Questions
20 questions
All Muscle Physiology and Contraction questions
- Q1. Which structure is the basic contractile unit of skeletal muscle that shortens during contraction?
- Q2. According to the sliding filament theory, which of the following occurs during muscle contraction?
- Q3. Which zone or band of the sarcomere remains constant in length during contraction, according to the sliding filament model?
- Q4. What triggers calcium release from the sarcoplasmic reticulum in skeletal muscle during excitation–contraction coupling?
- Q5. In the absence of sufficient intracellular calcium, muscle contraction cannot proceed because:
- Q6. Which process describes the repeated attachment, pivoting (power stroke), detachment, and re-cocking of myosin heads during muscle contraction?
- Q7. Which energy molecule is directly hydrolyzed by myosin ATPase to power muscle contraction and cross-bridge cycling?
- Q8. What structural arrangement at the neuromuscular junction ensures that one motor neuron can control multiple muscle fibers simultaneously?
- Q9. Which of the following correctly describes the sequence of events in excitation–contraction coupling in skeletal muscle, from membrane excitation to force gene…
- Q10. During muscle relaxation after a contraction, which mechanism primarily reduces cytosolic Ca²⁺ concentration to stop contraction?
- Q11. Which band(s) of the sarcomere shorten during contraction as thin and thick filaments slide past each other?
- Q12. Which structure in the muscle fiber ensures rapid propagation of action potentials into the interior of the fiber to trigger Ca²⁺ release from the SR?
- Q13. In isometric muscle contraction, which of the following is true?
- Q14. Which statement about smooth muscle contraction is correct compared to skeletal muscle contraction?
- Q15. Which protein complex undergoes a conformational shift upon Ca²⁺ binding to expose the myosin-binding sites on actin?
- Q16. What is the effect of a deficit in ATP availability (e.g., ischemia) on muscle contraction and relaxation?
- Q17. How does an increase in intracellular Ca²⁺ concentration lead to force generation in muscle fibers?
- Q18. Which of the following best describes “summation” of contractions in skeletal muscle physiology?
- Q19. Which structural protein in muscle fibers contributes to elasticity and returns stretched sarcomeres to resting length after contraction or stretch?
- Q20. During prolonged, repeated contractions (fatigue), which factor contributes to decreased force generation in muscle fibers?