What features do cardiac muscles exhibit that are not in skeletal muscles? Group of answer choices Calmodulin binds to Ca2+ and regulates cross-bridge cycling. Thin and thick filaments are arranged in various directions to alter force. Gap junctions allow direct transmission of electrical signals.
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Step 1: Identify the unique structural and functional features of cardiac muscle compared to skeletal muscle. Show more…
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When compared to skeletal muscle, what differences are observed in cardiac muscle? Cells are fusiform shaped, nonstriated, and contract as a sheet. The force of contraction depends on cell diameter rather than length. Intercalated discs are present and all cells are innervated. The sarcoplasmic reticulum is less complex. Cells are branched and there is a greater abundance of mitochondria. Contraction is triggered by an influx of potassium. The striations are more apparent, and T tubules are more abundant and occur at A-I junctions.
Briana D.
How cross-bridge cycling occurs, however, differs between muscle types. Which of the following highlights a difference in the cross-bridge formation between smooth muscle and skeletal muscle? Check all that apply. (A) Ca^2+ induces a chemical change in myosin in the thick filaments in smooth muscle; Ca^2+ induces a physical change in the thin filaments in skeletal muscle. (B) In smooth muscle, a light chain is phosphorylated so that myosin can interact with actin; in skeletal muscle, troponin and tropomyosin are moved so that myosin can interact with actin. (C) Thin filaments of a contracted smooth muscle cell can pull toward opposite ends of a thick filament, whereas all thin filaments of a contracted skeletal muscle pull toward the center of a thick filament. Explain why A and C apply to this question. 1). Cardiac muscle cells are joined -------------- by intercalated discs, which helps enhance the spread of action potentials throughout the heart. (a) end-to-end (b) side-by-side 2). Smooth muscles are___________ at their ends and arranged as sheets. These characteristics help them to contract as a single unit. (a) tapered (b) widened
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