describe how muscle fiber are arranged along the central surface of the frog
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Answer:
When you jump on a trampoline, your body has kinetic energy that changes over time. As you jump up and down, your kinetic energy increases and decreases with your velocity. Your kinetic energy is greatest, just before you hit the trampoline on the way down and when you leave the trampoline surface on the way up.
Explanation:
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Answer:
Muscle fibers are large multinucleated cells whose most obvious histological feature is cross-striations. The cytoplasm contains many myofibrils that include tiny cylinders consisting of bundles of myofilaments. The myofilaments include thick filaments mainly composed of myosin and thin filaments mainly composed of actin. The thick and thin filaments cause the cross-striations because of their regular overlap that is kept in register all across the diameter of the muscle fiber. The A-band corresponds to the thick filament. The I-band forms where the thin filament does not overlap the thick filament. Z-disks are centered in the I-band. The functional unit of contraction is the sarcomere, which extends from one Z-disk to the next. The whole point of muscles is to deliver force to the outside of the muscle. This is accomplished by transferring the force to cytoskeletal elements that connect the internal myofilaments to special proteins that penetrate the membrane. These proteins transfer the force to the extracellular matrix at special regions called costameres. It is found that dystrophin, the protein lacking in some kinds of muscular dystrophy, is concentrated at the costameres.