Grabación 04/02/2026

Notes

•USMLE Series Today, we discuss the sarcomere structure and its basic physiology. •Sarcomere Composition The sarcomere consists of two actin filaments and one myosin filament. It is measured from one Z line to the next Z line. The actin filament is the less strong component, while the M-band is part of the myosin filament, which is the strongest. •Bands and Contraction The I band, which contains actin, and the H band, which contains myosin, both contract during myocyte contraction. •Actin and Myosin Binding Sites Actin filaments bind at the Z line, whereas myosin filaments bind within the A band. This arrangement is essential for muscle contraction.