Concept explainers
To review:
Match the termsZ-disc, sarcomere, A band, H zone, I band, and M line with the most closely related descriptions given below:
The dark band containing the entire length of the thick filament
The band of proteins in the middle of the H zone
The boundary between sarcomeres
The functional unit of contraction
The middle region of the A band containing only thick filaments
The light band containing only thin filaments
Introduction:
Musclesare formed of muscle fibers. Muscle fibers are formed of proteins and usually, the fibers are striated. The basic unit of striated muscles issarcomere. The muscle fibers are formed of myofibrils. These myofibrils are formed of alternate sections of the sarcomere. Two important proteins of the filament are myosin and actin. Sarcomeresappear as light and dark bands. The different regions of the bands have different names such as I band, A band, H zone, Z-disc, and M line.
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Human Anatomy & Physiology (2nd Edition)
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- Graph A in this diagram represents A) summation and tetanus of a smooth muscle fibre. C) a simple skeletal muscle twitch c) summation and tetanus of a skeletal muscle fibre. D)simple smooth muscle twitch.arrow_forwardWhen Skeletal muscle contracts an arrangement of the alternating light and dark bands traversing each skeletal muscle cell changes. Which of the following statements is not correct. (Select one answer) (a) The dark A bands will remain a constant length(b) The space occupied by the H zone will not change(c) The light I bands will shorten(d) The z lines come closer together(e) The I band consists solely of thin actin filamentsarrow_forwardDiagram the arrangement of thick and thin filaments in a striated-muscle sarcomere, and label the major bands that give rise to the striated pattern. How does the position of the bands change during muscle contraction?arrow_forward
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