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Multiple Choice
Which of the following structures stores calcium within a muscle fiber?
A
Sarcoplasmic reticulum
B
Mitochondria
C
Myofibrils
D
T-tubules
Verified step by step guidance
1
Begin by understanding the role of calcium in muscle contraction. Calcium ions are crucial for the interaction between actin and myosin, the proteins responsible for muscle contraction.
Identify the structure within the muscle fiber that is responsible for storing and releasing calcium ions. This structure is known as the sarcoplasmic reticulum.
The sarcoplasmic reticulum is a specialized type of smooth endoplasmic reticulum found in muscle cells. It stores calcium ions and releases them when the muscle fiber is stimulated.
Compare the sarcoplasmic reticulum with other structures listed in the options: mitochondria, myofibrils, and T-tubules. Mitochondria are involved in energy production, myofibrils are the contractile units of muscle fibers, and T-tubules help transmit the action potential into the muscle fiber.
Conclude that the sarcoplasmic reticulum is the correct answer because it specifically functions to store and release calcium ions, which are essential for muscle contraction.