MUSCLE PHYSIOLOGY

Detailed explanation-1: -Muscle cells (myofibrils) are long parallel bundles of contractile proteins (myosin and actin); these flexible and elongated fibers are aligned in a parallel arrangement, with minimal air spaces, and separated by an extracellular matrix rich in glycoprotein.

Detailed explanation-2: -Each skeletal muscle consists of thousands of muscle fibers wrapped together by connective tissue sheaths. The individual bundles of muscle fibers in a skeletal muscle are known as fasciculi.

Detailed explanation-3: -The myofibrils are made up of thick and thin myofilaments, which give the muscle its striped appearance. The thick filaments are composed strands of the protein myosin, and the thin filaments are strands of the protein actin, along with two other muscle regulatory proteins, tropomyosin and troponin.

Detailed explanation-4: -Muscle cells are also called myofibrils. Reason: Muscle cells are very thin and elongated.