91 Muscles and Metabolism Glossary

Sarcomere: The functional unit (contractile unit) of a muscle fiber.

Excitation-Contraction Coupling: The physiological process of converting an electrical stimulus to a mechanical response.

T-Tubule: Any of the small tubules which run transversely through a striated muscle fiber and through which electrical impulses are transmitted from the sarcoplasm to the fiber’s interior.

Z-Disc: Defines the boundaries of a muscle sarcomere.

Isometric Contraction: A muscle contraction without motion.

Isotonic Contraction: when the force or tension in the muscle remains constant while the length of the muscle changes.

Eccentric Contraction: when the total length of the muscle increases as tension is produced.

Treppe: The graduated series of increasingly vigorous contractions that results when a corresponding series of identical stimuli is applied to a rested muscle.

Muscle Tone: The tension in the relaxed muscle.

Hypertrophy: The enlargement of an organ or tissue from the increase in size of its cells.

Atrophy: (of body tissue or an organ) waste away, especially as a result of the degeneration of cells, or become vestigial during evolution.

Functional Syncytium: a unit of contraction comprised of a network of electrically connected cardiac muscle cells.

Autorhythmicity: The quality of being autorhythmic, or generating its own rhythm

Hyperplasia: The enlargement of an organ or tissue caused by an increase in the reproduction rate of its cells, often as an initial stage in the development of cancer.

Caveolae: membrane microdomains described in many cell types involved in endocytosis, transcytosis, cell signaling, mechanotransduction, and aging.

Fibrosis: The thickening and scarring of connective tissue, usually as a result of injury.