The H-zone in the skeletal muscle fibre is due to:A extension of myosin filaments in the central portion of the A-band B the absence of myofibrils in the central portion of A-band C the central gap between myosin filaments in the A-band D the central gap between actin filaments extending through myosin filaments in the A-band
Question
The H-zone in the skeletal muscle fibre is due to:A extension of myosin filaments in the central portion of the A-band B the absence of myofibrils in the central portion of A-band C the central gap between myosin filaments in the A-band D the central gap between actin filaments extending through myosin filaments in the A-band
Solution
The H-zone in the skeletal muscle fibre is due to the extension of myosin filaments in the central portion of the A-band. So, the correct answer is A.
Here's a step-by-step explanation:
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The skeletal muscle fiber is composed of smaller units called myofibrils, which are further divided into contractile units called sarcomeres.
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Each sarcomere is composed of thick and thin filaments, known as myosin and actin filaments respectively.
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The A-band is the region of the sarcomere where the myosin and actin filaments overlap, and it appears dark under the microscope.
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The H-zone is a lighter region within the middle of the A-band where the actin filaments do not reach.
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This H-zone is visible due to the extension of myosin filaments only, as the actin filaments do not extend into this central portion of the A-band.
Therefore, the H-zone in the skeletal muscle fibre is due to the extension of myosin filaments in the central portion of the A-band.
Similar Questions
Which event does not happen during muscle contraction ?Actin filaments move towards H-zone Decreased length of myosin filament Decreased length of sarcomereLength of A-band remains unchanged.
Contraction of muscle fibre takes place by the sliding of :-A Thin filaments over the actin filaments B Thick filaments over the thin filaments C Thin filaments over the thick filaments D Thick filaments over the myosin filaments
Complete the sentences by choosing the correct word from each dropdown menu.In resting muscle fiber, a is normally 2.0 to 2.5 micrometers long.This is the optimum length for producing maximum when the muscle contracts.If a muscle fiber is overly contracted, the filaments but against the Z discs.Conversely, if the muscle fiber is overly stretched, there is not enough overlap between the thick and myofilaments.Therefore, if the thick and thin filaments do not overlap, very few are formed.
Which of the following happens as actin and myosin filaments slide past each other during muscle contraction?
During muscle contraction, which area remains the same size?Group of answer choicesH zonesI bandsnone of the listed regions remain the same sizeA bands
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