Which of the following shortens in length during skeletal mucle contraction? select all that apply Action filaments H- zone A- band  I- band

Thick and thin myofilaments have different properties. For each phrase below, indicate whether the filament described is thick or thin (write thick or thin in the blanks).__(1) contains myosin heads__(2) contains actin__(3) does not lie in the H zone__(4) contains myosin__(5) attaches to a Z disc__(6) does not lie in the I band

What do the calcium ions that are released into the cytoplasm during contraction bind to? tropomyosin actin the Z-line myosin O troponin

A bands: Dark areas that correspond to the areas where thick filaments are present. • I hands: Light areas that contains only thin filaments. . Z line: A protein disk within the I band that anchors the thin filaments and connects adjacent myofibrils. • H zone: Located in the middle of each A band, this lighter stripe appears corresponding to the region between the thin filaments. • M line: Protein fibers that connect neighboring thick filaments. Sarcomeres: The region of the myofibril between two Z lines. ** Keep in mind, this information is crucial for your understanding of the sliding filament theory.