They move through the ecosystem
A skeletal muscle<span> fiber is surrounded by a plasma membrane called the sarcolemma, which contains sarcoplasm, the cytoplasm of muscle cells. A muscle fiber is composed of many fibrils, which give the cell its striated appearance.</span>
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c. thyroxine </span><span>The thyroid releases too much of the hormone thyroxine, which increases the person's basal metabolic rate.</span>
