Which of the following is true about sarcomeres?
Correct answer: D. The A band contains both actin and myosin filaments
- A. Actin filaments are only found in the I band
- B. The sarcomeres contribute to the striated appearance of smooth muscle cells
- C. Sarcomeres are functional units of skeletal and smooth muscle cells
- D. The A band contains both actin and myosin filaments
Explanation
Parts of the A band contain both thick and thin filaments, so both myosin and actin filaments are present.
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About Muscle Contraction
Muscle contraction is explained by the sliding filament model, in which myosin heads pull actin filaments within sarcomeres using ATP. The topic covers calcium, troponin, tropomyosin, the neuromuscular junction and relaxation, with attention to how filament length stays almost constant while the sarcomere shortens.
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