ATI RN
Multiple Choice Questions on Muscular System Questions
Question 1 of 5
What is a sarcomere ?
Correct Answer: C
Rationale: A sarcomere is the contractile unit of muscle, a segment of a myofibril between Z-lines, containing overlapping actin and myosin myofilaments. It's not a cancer (sarcoma), cytoplasm (sarcoplasm), or membrane (sarcolemma), but a structural section where sliding filaments shorten during contraction. Defining myofibril organization, sarcomeres' repetitive nature enables muscle shortening, distinguishing them from pathological or cellular envelope terms, central to understanding muscle mechanics at the microscopic level.
Question 2 of 5
Which feature is shared by cardiac muscle cells and skeletal muscle cells?
Correct Answer: A
Rationale: Both cardiac and skeletal muscle cells display striations banded patterns from sarcomere alignment unlike smooth muscle. Intercalated discs, branching, and involuntary control are cardiac-specific, aiding heart synchronization and automaticity. Striations reflect shared contractile machinery, distinguishing them from non-striated smooth muscle, key to their histological and functional similarity.
Question 3 of 5
Skeletal muscle cells can be characterised as:
Correct Answer: D
Rationale: Skeletal muscle is striated (sarcomere-banded), voluntary (somatic control), and multinucleate (syncytial), unlike smooth (unstriated, involuntary, uninucleate) or cardiac (striated, involuntary, uninucleate) muscle. This trio defines its role in conscious movement, distinguishing it in structure and function, key to its physiological classification.
Question 4 of 5
What are the muscles known as triceps brachii, biceps femoris and quadriceps femoris named according to? Their:
Correct Answer: B
Rationale: These muscles triceps brachii (three origins, arm), biceps femoris (two origins, thigh), quadriceps femoris (four origins, thigh) are named by origin count ('tri-,' 'bi-,' 'quad-') and location ('brachii' for arm, 'femoris' for femur). Size, shape, fibre direction, or insertions aren't specified. This origin-location convention aids anatomical identification, distinguishing them from size- or shape-based names, reflecting muscle attachment points critical for function.
Question 5 of 5
Which of these events is necessary for the contraction of a muscle cell?
Correct Answer: B
Rationale: ATP hydrolysis to ADP and phosphate energizes myosin cross-bridges, enabling them to pull actin, driving contraction. Myosin doesn't shorten, calcium binds troponin (not tropomyosin), and calcium returns to the sarcoplasmic reticulum post-contraction. This energy step distinguishes contraction's power source, essential for filament sliding, contrasting with regulatory or recovery phases.