PHYSIOLOGY
MUSCLE STRUCTURE FUNCTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Dark, thick and myosin
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Dark, thin, and actin
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Dark, thin, and myosin
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Light, thin and actin
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Detailed explanation-1: -The A-band appears black, comprising thick filaments that are partially overlapped with thin filaments . The thick and thin filaments overlap contain myosin to form dark bands called A bands. Alone, thin filaments form light bands, called I bands, and are made from actin.
Detailed explanation-2: -The dark A band consists of parallel myosin thick filaments, in a hexagonal arrangement in cross-section. The thick filaments of a single sarcomere are connected to each other by means of the M disc at their centres.
Detailed explanation-3: -The light bands contain actin(thin filament) and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin(thick filament).
Detailed explanation-4: -There are two types of myofilaments. Thin actin filament and thick myosin filament. Both the filaments are arranged alternately. The region where both myofilaments are present is seen as dark and is called as dark band.
Detailed explanation-5: -The light bands are called I bands and contain only thin filaments. The dark bands are called A bands and contain thick and thin filaments, with the thick filaments running the entire length of the A band. Thus the length of the thick filament determines the length of the A band.