Term | Definition |
Epimysium | a sheath of fibrous elastic tissue surrounding a muscle. |
Perimysium | the sheath of connective tissue surrounding a bundle of muscle fibers. |
Endomysium | the delicate connective tissue surrounding the individual muscular fibers within the smallest bundles—compare epimysium. |
Tendon | a flexible but inelastic cord of strong fibrous collagen tissue attaching a muscle to a bone |
Muscle Fiber | any of the elongated cells characteristic of muscle. |
Myoblast | a type of embryonic progenitor cell that differentiates to give rise to muscle cells. Skeletal muscle fibers are made when Myoblasts fuse together; muscle fibers therefore have multiple nuclei |
Sarcoplasm | the cytoplasm of striated muscle cells. |
Transverse Tubules | a deep invagination of the sarcolemma, which is the plasma membrane of skeletal muscle and cardiac muscle cells |
Action Potential | the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell. |
Myofilaments | are the filaments of myofibrils constructed from proteins. The principal types of muscle are striated muscle, obliquely striated muscle and smooth muscle. |
Thin Filaments | one of the contractile elements in muscular fibers and other cells; in skeletal muscle, the actin filaments are about 7.5 nm wide and 1 mcm long, and attach to the transverse Z filaments. |
Thick Filaments | one of the contractile elements in skeletal, cardiac, and smooth muscle fibers; in skeletal muscle, the filament is about 15 nm thick and 1.5 mcm long. |
Sarcoplasmic Reticulum | a system of membrane-bound tubules that surrounds muscle fibrils, releasing calcium ions during contraction and absorbing them during relaxation. |
Triad | The junction between the t tubules and the sarcoplasmic reticulum in striated muscle. |
Cisternae | An ultramicroscopic space or channel occurring between the membranes of the flattened sacs of the endoplasmic reticulum, the Golgi complex, or the two membranes of the nuclear envelope. |
Sarcomeres | are divided into bands of filaments made of actin or myosin. |
Myofibrils | are filaments of the proteins myosin and actin; these filaments slide past one another as the muscle contracts and expands. |
Strated | |
Troponin | is a complex of three regulatory proteins (troponin C, troponin I, and troponin T) that is integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle. |
Tropomyosin | is a two-stranded alpha-helical coiled coil protein found in cell cytoskeletons. |
Active site | is a small port in an enzyme where substrate molecules bind and undergo a chemical reaction |
Actin | is the most abundant protein in most eukaryotic cells. It is highly conserved and participates in more protein-protein interactions than any known protein. |
Myosin | are a large superfamily of motor proteins that move along actin filaments, while hydrolyzing ATP. |
Newromusclar Junction | is a place in the body where the axons of motor nerves meet the muscle, allowing them to transmit messages from the brain that cause the muscle to contract and relax. |
Sarcolemma | (Sarco (from Sarx) from Greek; Flesh, and Lemma from Greek; sheath.) also called the myolemma, is the cell membrane of a striated muscle fiber cell. |