Muscle physiology – types, ultrastructure, contraction - One Line Questions

1. A motor unit consists of: — A single motor neuron and all the muscle fibers it innervates
2. What is tetanus in muscle physiology? — A sustained, forceful contraction due to rapid stimulation
3. Which protein filament is considered the 'thick' filament in the sarcomere? —
4. Which protein is responsible for the 'spring-like' action that returns the myosin head to its resting position after ATP binding? — Myosin
5. Which of the following is NOT a component of the thin filament in a sarcomere? — Myosin
6. What is the primary function of the M-line in the center of the sarcomere? — Anchoring thick filaments and stabilizing the sarcomere
7. In the context of muscle contraction, the 'rigor mortis' state is characterized by: — Sustained muscle contraction due to the inability of myosin to detach from actin in the absence of ATP
8. A single muscle twitch consists of which phases? — Latent period, contraction, and relaxation
9. What neurotransmitter is released at the neuromuscular junction to initiate muscle contraction? — Acetylcholine
10. The sarcolemma is the cell membrane of a muscle fiber. What is its specialized name? — Sarcolemma
11. Which cellular organelle is most abundant in muscle fibers to meet the high energy demands of contraction? — Mitochondria
12. What is the state of the myosin head when it is attached to actin and pulling? — Energized by ATP hydrolysis
13. What is the primary energy source for muscle contraction? — ATP
14. Which of the following is a characteristic of slow-twitch (Type I) muscle fibers? — High myoglobin content and fatigue resistant
15. Fast-twitch (Type II) muscle fibers are typically characterized by: — Low myoglobin content and anaerobic metabolism
16. The process by which a muscle fiber generates tension is called: — Contraction
17. Which of the following is a characteristic feature of skeletal muscle tissue? — Voluntary control and striated appearance
18. Which type of muscle contraction occurs when the muscle generates tension but does not change length? — Isometric contraction
19. Which of the following accurately describes the role of tropomyosin? — It blocks the myosin-binding sites on actin in a relaxed muscle.
20. What is the role of ATP in muscle contraction, specifically in the 'power stroke'? — It is hydrolyzed to ADP and Pi, releasing energy for the myosin head to pivot.
21. In concentric isotonic contraction, the muscle: — Shortens while generating tension
22. Smooth muscle tissue is characterized by: — Single central nucleus and lack of striations
23. The 'thin' filaments of the sarcomere are primarily composed of which protein? — Actin
24. Muscle fatigue is often associated with the depletion of: — ATP and glycogen
25. The sarcoplasm is the cytoplasm of a muscle cell. What is a key component found in high concentrations within it? — Glycogen granules
26. The H zone within the sarcomere is the central region of the A band containing: — Only myosin filaments
27. The I band of the sarcomere contains: — Only actin filaments
28. The A band of the sarcomere represents the region containing: — Both thick and thin filaments
29. The contraction of smooth muscle is generally: — Slow and involuntary
30. Which of the following describes the 'latch state' of smooth muscle? — Sustained contraction with minimal ATP usage
31. The basic contractile unit of a muscle fiber is called the: — Sarcomere
32. During muscle contraction, the H zone: — Shortens
33. Eccentric contraction is when the muscle: — Lengthens under tension
34. Which type of muscle tissue has the ability to regenerate to a limited extent? — Smooth muscle
35. Intercalated discs are specialized junctions found in: — Cardiac muscle
36. What is the primary difference between smooth muscle and skeletal muscle regarding control? — Skeletal muscle is voluntary, smooth muscle is involuntary.
37. The binding of which ion to troponin causes a conformational change, allowing myosin to bind to actin? — Calcium (Ca2+)
38. The T-tubules (transverse tubules) are invaginations of the sarcolemma that: — Conduct action potentials deep into the muscle fiber
39. Which of the following best describes the function of the epimysium? — Surrounds the entire muscle
40. Which of the following structures connects a muscle fiber to a motor neuron axon terminal? — Neuromuscular junction
41. The role of acetylcholinesterase at the neuromuscular junction is to: — Break down acetylcholine, terminating the signal
42. The 'all-or-none' principle in muscle physiology refers to: — The contraction of a single muscle fiber.
43. What prevents the thin and thick filaments from sliding back to their original positions during muscle relaxation? — The absence of calcium ions
44. The sliding filament theory explains muscle contraction as: — The sliding of thin filaments past thick filaments.
45. What is the function of the Z-lines (or Z-discs) in a sarcomere? — They mark the boundaries of a sarcomere and anchor thin filaments.
46. What is the role of myoglobin in muscle cells? — To store oxygen
47. What is the function of creatine phosphate in muscle cells? — To rapidly regenerate ATP from ADP
48. What is the function of the sarcoplasmic reticulum in muscle contraction? — To store and release calcium ions
49. Which of the following is a characteristic of cardiac muscle cells? — Involuntary control and presence of intercalated discs
50. Cardiac muscle is primarily found in which part of the body? — Walls of the heart
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