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Biological Sciences

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The Integumentary, Skeletal and Muscular Systems

Question
7 out of 10
 

The release of which ion from the sarcoplasmic reticulum of a muscle fiber directly stimulates muscle contraction?

A Sodium
B Postassium
C Calcium
D Phosphorus
Ans. C

Calcium is stored in the sarcoplasmic reticulum of muscle cells, and as the muscle cell becomes depolarized, it is released into the sarcoplasm, where it directly stimulates troponin to initiate contraction. Sodium and potassium are involved only in the nervous signal that depolarizes the sarcolemma (choices A and B), and phosphorus is not relevant in this context.

The Integumentary, Skeletal and Muscular Systems Flashcard List

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