Title: Mastering A&P - Chapter 9 Flashcards | Quizlet
Headings: Mastering A&P - Chapter 9
Mastering A&P - Chapter 9
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Content: ACh diffuses into the synaptic cleft, binds to the receptor proteins on the junctional folds of the muscle sarcolemma (motor end plate), and initiates graded potentials. These graded potentials sum to an action potential, thus initiating excitement of the muscle fiber. The action potential propagates along the sarcolemma. As the action potential spreads down the T tubules of the triads, voltage-sensitive tubule proteins change shape. How does the shape change of these proteins lead to contraction? It allows calcium to exit the sarcoplasmic reticulum and enter the cytosol. *As the action potential propagates, it changes the shape of T tubule proteins. These proteins are linked to calcium channels in the terminal cisterns of the sarcoplasmic reticulum. When these proteins' calcium channels open, a massive amount of calcium flows into the cytosol. Which selection correctly describes the role of calcium in coupling?