Which of the following will take place during skeletal muscle contraction?
During contraction, the I band decreases in size as thin filaments penetrate the A band. The H band--the pa of the A band with only thick filaments--diminishes in width as the thin filaments completely overlap the thick filaments. A net result is that each sarcomere, and consequently the whole cell (fiber), is greatly shoened. Also know: The light I band is divided by the dark Z line, and the dark A band has the lighter H band in its center. A transverse M line is seen in the middle of the H band, and this line plus the narrow light areas on either side of it are sometimes called the pseudo-H zone. The area between two adjacent Z lines is called a sarcomere. The thick filaments, which are about twice the diameter of the thin filaments, are made up of myosin; the thin filaments are made up of actin, tropomyosin, and troponin. The lighter H bands in the center of the A bands are the regions where, when the muscle is relaxed, the thin filaments do not overlap the thick filaments. Ref: Mescher A.L. (2010). Chapter 10. Muscle Tissue. In A.L. Mescher (Ed), Junqueira's Basic Histology: Text & Atlas, 12e.
A band shoen
Both H and I band shoen
Both A and I band shoen
Both A and H band shoen