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Unformatted text preview: 11-14-07 anatomy notes1.Muscular Systema.Muscle Physiologyi.Motor Unit- 1 nerve fiber + ALL muscle fibers it innervates; 2-2000 muscle cells1.Nerve-hundreds of fibers2.Groups of nerve fibers from a nerve enter a muscle3.Each nerve fiber (axon) subdivides into 2-2000 axon branches and these form axon terminals and end feet at the neuromuscular junction4.Within the neuromuscular junction each end foot associates w/an end plate of muscle fiber5.An action potential travels along an axon to ALL muscle fibers in a motor unita.All muscle cells in unit contract at same timeii.Isolated Muscle Preparations1.Typesa.Isomeric-muscle connected at 2 pointsi.When stimulated, it does NOT move or shorten, ONLY tension increasesii.Because it cannot move, NO work is done in isomeric contractionb.Isotonic-muscle connected at one end and the opposite end is feely movablei.When stimulated it moves, shortens, and does work a.changes shapeii.Work=force X distancea.5lbs. X 3ft. = 15ft/lb....
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