ANATOMY

Detailed explanation-1: -A myofibril (also known as a muscle fibril or sarcostyle) is a basic rod-like organelle of a muscle cell. Skeletal muscles are composed of long, tubular cells known as muscle fibers, and these cells contain many chains of myofibrils. Each myofibril has a diameter of 1–2 micrometres.

Detailed explanation-2: -Within a muscle fiber, proteins are organized into organelles called myofibrils that run the length of the cell and contain sarcomeres connected in series. Because myofibrils are only approximately 1.2 m in diameter, hundreds to thousands (each with thousands of sarcomeres) can be found inside one muscle fiber.

Detailed explanation-3: -Myofibrils are long contractile fibres, groups of which run parallel to each other on the long axis of the myocytes (long single multinucleated cells that combine to form the muscle).

Detailed explanation-4: -Myofibrils are composed of overlapping thick and thin myofilaments organized into distinct, repeating units called sarcomeres. Z-discs (also called Z-lines; Z in Figures 5.1, 5.2), comprised largely of -actinin, form the boundaries of sarcomeres and provide an attachment site for thin filaments.

Detailed explanation-5: -The contractile functional unit of the myofibril is called the sarcomere. The myofibrils have a characteristic banding pattern detected under a light microscope referred to as striations. The main function of the myofibrils is to produce muscle contraction and relaxation.