MUSCLE PHYSIOLOGY

PHYSIOLOGY

MUSCLE CONTRACTION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
When a muscle is in a contracted position, what is the relationship between actin filaments?
A
They are on top of one another
B
They are beside each other
C
They are close to each other
D
They are far apart from each other
Explanation: 

Detailed explanation-1: -Muscle contraction thus results from an interaction between the actin and myosin filaments that generates their movement relative to one another. The molecular basis for this interaction is the binding of myosin to actin filaments, allowing myosin to function as a motor that drives filament sliding.

Detailed explanation-2: -The actin–myosin interaction produces two types of movements: force generation between actin filaments leading to contractions, such as in muscle contraction, cell motility, and cytokinesis; and transport of subcellular organelles and macromolecular complexes by myosin motors along actin filaments.

Detailed explanation-3: -Cross-bridge theory states that actin and myosin form a protein complex (classically called actomyosin) by attachment of myosin head on the actin filament, thereby forming a sort of cross-bridge between the two filaments.

Detailed explanation-4: -Abstract. Muscle contraction occurs when the thin actin and thick myosin filaments slide past each other. It is generally assumed that this process is driven by cross-bridges which extend from the myosin filaments and cyclically interact with the actin filaments as ATP is hydrolysed.

Detailed explanation-5: -During contraction, the myosin heads extend from the thick filament surface and attach to actin in the thin filaments, causing the filaments to slide past each other in a cyclic, ATP-driven process.

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