Lesson 4.2 Muscles Key Terms

Lesson 4.2 Muscles – Key Terms

Actin / A contractile protein that is part of the thin filaments in muscle fibers
Afferent neurons / Nerve cells that carry impulses towards the central nervous system
Cardiac muscle / Striated muscle fibers (cells) that form the wall of the heart; stimulated by the intrinsic conduction system and autonomic motor neurons
Carpal tunnel syndrome / A condition caused by compression of the median nerve in the carpal tunnel and characterized especially by weakness, pain, and disturbances of sensation in the hand and fingers
Contract / To shorten and thicken
Efferent neurons / Nerve cells that conduct impulses away from the central nervous system
Endomysium / The delicate connective tissue surrounding the individual muscular fibers within the smallest bundles
Epimysium / The external connective-tissue sheath of a muscle
Fascicle / A small bundle or cluster, especially of nerve or muscle fibers
Insertion / The attachment of a muscle tendon to a moveable bone or the end opposite the origin
Muscle / An organ composed of one of the three types of muscular tissue (skeletal, cardiac, and smooth), specialized for contraction to produce voluntary and involuntary movements of parts of the body
Myofibril / A threadlike structure, extending longitudinally through a muscle fiber (cell) consisting mainly of think filaments (myosin) and thin filaments (actin, troponin, and tropomyosin)
Myosin / The contractile protein that makes up the thick filaments of muscle fibers
Nerve / A cordlike bundle of neuronal axons and/or dendrites and associated connective tissue coursing together outside the central nervous system
Origin / The attachment of a muscle tendon to a stationary bone or the end opposite the insertion
Perimysium / The connective-tissue sheath that surrounds a muscle and forms sheaths for the bundles of muscle fibers
Plexus / Network of interlacing blood vessels or nerves
Rigor mortis / Temporary rigidity of muscles occurring after death
Sarcomere / Any of the repeating structural units of striated muscle fibrils
Skeletal muscle / An organ specialized for contraction, composed of striated muscle fibers (cells), supported by connective tissue, attached to bone by a tendon or aponeurosis, and stimulated by somatic motor neurons
Sliding filament mechanism / The explanation of how thick and thin filaments slide relative to one another during striated muscle contraction to decrease sarcomere length
Smooth muscle / A tissue specialized for contraction, composed of smooth muscle fibers (cells), located in the walls of hollow internal organs, and innervated by the autonomic motor neurons
Striation / Any of the alternate dark and light cross bands of a myofibril of striated muscle
Tropomyosin / A protein of muscle that forms a complex with troponin regulating the interaction of actin and myosin in muscular contraction
Troponin / A protein of muscle that together with tropomyosin forms a regulatory protein complex controlling the interaction of actin and myosin and that when combined with calcium ions permits muscular contraction

Human Body Systems Lesson 4.2 Muscles – Key Terms – Page 1