Multiple Choice
The interaction between which protein and ion initiates muscle contraction according to the sliding filament theory?
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9. Muscle Tissue
Sliding Filament Theory and the Sarcomere
Multiple Choice
Which event occurs according to the sliding filament theory of muscle contraction?
A
Actin and myosin filaments shorten during contraction.
B
Calcium ions are released from the sarcoplasmic reticulum and bind to myosin.
C
ATP is not required for the detachment of myosin heads from actin.
D
Myosin heads bind to actin, forming cross-bridges.
Verified step by step guidance1
Understand the sliding filament theory: This theory explains how muscles contract by the sliding of actin and myosin filaments past each other, rather than shortening themselves.
Identify the role of calcium ions: Calcium ions are released from the sarcoplasmic reticulum and bind to troponin, not myosin, which causes a conformational change that exposes binding sites on actin filaments.
Recognize the importance of ATP: ATP is crucial for muscle contraction as it provides the energy needed for myosin heads to detach from actin after forming cross-bridges.
Focus on cross-bridge formation: Myosin heads bind to actin filaments, forming cross-bridges, which is a key event in muscle contraction according to the sliding filament theory.
Clarify the misconception about filament shortening: Actin and myosin filaments do not shorten; they slide past each other, which leads to muscle contraction.
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