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Multiple Choice
The final "go" signal for skeletal muscle contraction is __________.
A
an increase in intracellular calcium ion levels
B
an increase in extracellular calcium ion levels
C
a decrease in intracellular calcium ion levels
D
a decrease in extracellular calcium ion levels
Verified step by step guidance
1
Understand that skeletal muscle contraction is initiated by a signal that leads to the interaction of actin and myosin filaments within the muscle fibers.
Recognize that calcium ions play a crucial role in muscle contraction by binding to troponin, which causes a conformational change that allows myosin to bind to actin.
Identify that the source of calcium ions for muscle contraction is primarily from the sarcoplasmic reticulum, an intracellular organelle, which releases calcium into the cytosol.
Consider that an increase in intracellular calcium ion levels is necessary to trigger the binding of calcium to troponin, thus facilitating muscle contraction.
Conclude that the final 'go' signal for skeletal muscle contraction is an increase in intracellular calcium ion levels, as this directly leads to the interaction of actin and myosin, resulting in contraction.