Multiple Choice
In the structure of skeletal muscle, the connective tissue structures that attach muscle to bone are called:
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9. Muscle Tissue
Structure of a Skeletal Muscle
Multiple Choice
In skeletal muscle fibers, which structure serves as the primary intracellular storage site for calcium ions (Ca2+) used to trigger contraction?
A
Transverse (T) tubules
B
Myofibrils
C
Synaptic cleft at the neuromuscular junction
D
Sarcoplasmic reticulum (especially the terminal cisternae)
Verified step by step guidance1
Understand the role of calcium ions (Ca2+) in skeletal muscle contraction: Ca2+ ions are essential for initiating the interaction between actin and myosin filaments, which leads to muscle contraction.
Identify the intracellular structures involved in calcium storage and release within skeletal muscle fibers: Key structures include the sarcoplasmic reticulum, transverse (T) tubules, myofibrils, and the synaptic cleft at the neuromuscular junction.
Recall the function of the sarcoplasmic reticulum (SR): The SR is a specialized form of smooth endoplasmic reticulum in muscle cells that stores Ca2+ ions and releases them upon stimulation to trigger contraction.
Recognize the role of the terminal cisternae of the sarcoplasmic reticulum: These enlarged areas of the SR are located near the T tubules and serve as the primary sites for Ca2+ storage and rapid release during muscle activation.
Conclude that among the options, the sarcoplasmic reticulum, especially the terminal cisternae, is the primary intracellular storage site for Ca2+ ions used to trigger skeletal muscle contraction.
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