Which of the following statements about muscle is true? Bbl6epute oAnH OTBeT: a. In all three muscle types dihydropyridine antagonists or blockers increase strength of contraction b. Actin and myosin filaments don participate in contraction of smooth muscles c. In all three muscle types (cardiac skeletal, and smooth) all cells contract as a unit d. In all three muscle types calcium is involved in contraction e. All three muscle types are innervated by the autonomic nervous system

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Which of the following statements about muscle is true? Bbl6epute oAnH OTBeT: a. In all three muscle types dihydropyridine antagonists or blockers increase strength of contraction b. Actin and myosin filaments don participate in contraction of smooth muscles c. In all three muscle types (cardiac skeletal, and smooth) all cells contract as a unit d. In all three muscle types calcium is involved in contraction e. All three muscle types are innervated by the autonomic nervous system

Answer 1

The correct answer is:d. In all three muscle types (cardiac, skeletal, and smooth) calcium is involved in contraction.Explanation:- Calcium ions play a crucial role in muscle contraction by initiating the interaction between actin and myosin filaments.- In skeletal muscles, calcium is released from the sarcoplasmic reticulum into the cytoplasm, leading to the activation of the contractile machinery.- In cardiac muscles, calcium influx through L-type calcium channels and release from the sarcoplasmic reticulum are essential for the initiation and regulation of contraction.- In smooth muscles, calcium is released from the sarcoplasmic reticulum or enters the cell through voltage-gated calcium channels, triggering contraction.The other options are incorrect:a. Dihydropyridine antagonists or blockers specifically target voltage-gated calcium channels in skeletal muscles and do not increase the strength of contraction in all three muscle types.b. Actin and myosin filaments are involved in the contraction of smooth muscles, although the mechanism is different from that in skeletal muscles.c. Not all cells in all three muscle types contract as a unit; for example, in skeletal muscles, individual muscle fibers contract independently.e. Skeletal muscles are innervated by the somatic nervous system, while smooth and cardiac muscles are innervated by the autonomic nervous system.

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