Question

What are the major parts of a skeletal muscle fiber, and what is the function of each part?

Answer 1

Muscle fibers are the contractile cells present in a muscle. Muscle fibers are usually quiescent but can be activated by exercising.

Complete answer:
Bands of skeletal muscles are seen when skeletal muscles are viewed under a microscope. This distinct banding of the skeletal muscles is apparent because of the arrangement of the cytoskeletal elements. The thick filaments of the skeletal muscle fibers are known as myosin and the thin filaments are known as actin. These filaments of the muscle fibers are arranged in repeating units called sarcomeres. A sarcomere is the fundamental contractile unit of a muscle fiber. The muscle contractions occur because of the reaction between actin and myosin.
The organelles in the muscle fibers are arranged in a way to perform their functions. The sarcolemma is the cell membrane of the muscle fibers. The cytoplasm of the muscle fibers is called the sarcoplasm. The myofibrils of muscle fibers are located in the sarcoplasm. Myofibrils are rod-like units of muscle fibers. Many myofibrils come together to form muscle fibers. The mitochondria of the muscle fibers are located between the myofibrils. They provide energy to the muscle fibers as myosin requires ATP to function. The sarcoplasmic reticulum of the muscle fibers surrounds the myofibrils. The sarcoplasmic reticulum holds a reserve of calcium ions. These calcium ions are important for muscle contraction.

Note:
Multiple bundles of muscle cells (myocytes) are called muscle fibers. Almost all skeletal muscles are attached to bones with the help of tendons. Tendons are collagen fibers that attach muscles to bones. Development of muscle fibers from the developmental myoblasts is called myogenesis.