Myofilamentum

Myofilamentum is the technical term for the protein filaments that are responsible for muscle contraction. These filaments are found within muscle cells, specifically in organelles called myofibrils. There are two main types of myofilaments: thick filaments and thin filaments. Thick filaments are primarily composed of the protein myosin, while thin filaments are mainly composed of the protein actin. In addition to actin, thin filaments also contain regulatory proteins called tropomyosin and troponin. The arrangement of these myofilaments in a repeating pattern creates the characteristic striated appearance of skeletal and cardiac muscle tissue. During muscle contraction, the myosin heads of the thick filaments bind to actin molecules on the thin filaments, pulling the thin filaments closer together. This sliding filament model is the fundamental mechanism by which muscles shorten and generate force. The interaction between actin and myosin is regulated by calcium ions and the troponin-tropomyosin complex, which controls the exposure of myosin-binding sites on the actin filament.