HSC 120 Lecture Notes - Lecture 9: Neuromuscular Junction, Skeletal Muscle, Myofilament
Document Summary
A muscle has a fibrous covering called the epimysium. A muscle is composed of a bundle of fascicles. A fascicle is composed of muscle cells surrounded by endomysium. The connective tissue of the muscle come together at the end of the muscle cell or fiber to form a tendon. A muscle cell is composed of myofibrils. Each myofibril is composed of thick and thin myofilaments arranged in sarcomeres. Thick and thin myofilaments are composed of protein molecules. Sarcomeres extend z line to z line. Myosin subunits look like a double deaded golf club. Head is referred to as a cross bridge. Actin subunits make up a double chain of beads twisted together. Tropomyosin is a thread that holds the actin chained together. Physiological characteristics of muscle tissue: excitability, conductivity, contractility, extensibility, elasticity. Stimulation of a muscle cell by a nerve happens at a neuromuscular junction. An electrical stimulation along the nerve cell results in the release of acetylcholine.
