This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
Which of the following is true regarding the action potential of skeletal muscle? 
Select and explain. 
A. It spreads inward to all pas of the muscle the T-tubules, B. It has a prolonged plateau phase, C. It causes the immediate uptake of Ca2+ into the lateral sacs of the sarcoplasmic reticulum, D. It is longer than the action potential of cardiac muscle
A: It spreads inward to all pas of the muscle the T-tubules
Answer: A: It spreads inward to all pas of the muscle the T-tubules 
Explanation: Depolarization of the muscle fibers is essential for initiating muscle contraction. The action potential of skeletal muscle is transmitted to all of the fibrils along T-tubules, triggering the release of Ca2+ from the lateral sacs of the sarcoplasmic reticulum next to the T-system. The electrical events in skeletal muscle and the ionic fluxes underlying them are similar to those in nerve. In contrast, the action potential in cardiac muscle is longer and has a prolonged plateau phase.