Martinez-ENG113 Nursing Assistant. Lippincott | thePoint Free CNA Practice. Annette_Bitups K. PAL 4.0 Part A When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length. True False Submit Request Answer

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1. The sarcomere is the functional unit of a muscle fiber, delimited by Z-discs.

2. The key bands within the sarcomere include:
   - The I band, which contains only thin filaments.
   - The A band, which spans the entire region where thick filaments (and overlapping thin filaments) are present.
   - The H zone, which is the central part of the A band where there is only thick filament and no overlap with thin filament.

3. During muscle contraction:
   - The I bands become smaller because the thin filaments slide into the central region.
   - The H zones disappear as the thin filaments completely overlap the thick filaments.
   - The A bands remain the same length because they are defined by the length of the thick filaments, even though the thin filaments slide towards the center.

4. Based on this analysis, the statement is correct.

$$
\text{Answer: True}
$$
The statement is true. During muscle contraction, the I bands become smaller, the H zones disappear, and the A bands stay the same length.

Martinez-ENG113 Nursing Assistant. Lippincott | thePoint Free CNA Practice. Annette_Bitups K. PAL 4.0 Part A When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length. True False Submit Request Answer

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