PHYSIOLOGY
MICROSCOPIC MUSCLE ANATOMY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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I Band
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A Band
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C Band
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New Kids on the Block Band
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Detailed explanation-1: -Z-lines mark the boundaries of the sarcomeres. The dark staining region in the centre of the sarcomere is called the A (anisotropic) band. The lighter staining band, through which the Z-line passes is called the I (isotropic) band. A diagram of a muscle sarcomere is shown below.
Detailed explanation-2: -Thin filaments (or actin filament) are anchored at one end at the Z-band. Titin is anchored to both the Z-band and the M-line. Thick filaments are anchored in the middle of the sarcomere at the M-line. The I-band is the region on either side of a Z-disc that contains only thin filaments and titin.
Detailed explanation-3: -In physiology, isotropic bands (better known as I bands) are the lighter bands of skeletal muscle cells (a.k.a. muscle fibers). Isotropic bands contain only actin-containing thin filaments. The darker bands are called anisotropic bands (A bands).