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Chapter 6 The Muscular System I.Overview of Muscle Tissues • Differ in cell structure,location, and how they are stimulated to contract • Smooth and skeletal muscle cells are elongated and called ________________________ • Contraction-shortening-depends on 2 types of myofilaments • Terms myo-,sarco- and mys- refers to muscleexample-muscular cytoplasm is called ___________________. Muscle fibers sarcoplasm skeletal muscle – – – – – attach to skeleton and form smoother contours of body huge,cigar shaped and ______________________ largest of muscle fibers-as much as 30 cm in length __________________________with obvious stripes ___________________since only muscle subject to conscious control Voluntary muscle multinucleate striated – – – – However,subject to involuntary reflexes Tire easily and requires rest Fairly fragile Bound by ___________________________which provides strength and support Connective tissue – Each muscle fiber contained in a declicate connective tissue sheath called ___________________________ – _________________________-connective tissue wrapping a bundle of fibers called a _________________ perimysium endomysium fascicle – ___________________________= many fascicle bound together w/ this tough coat – Epimysia blend into the strong_,cordlike_________ or aponeurose(sheetlike) that connect muscle to bones,cartilages or connective tissue – Other functions of tendons-besides movementare durability and conservation of space epimysium tendons Smooth Muscle • • • • No striations and is involuntary Mainly in walls of hallow visceral organs such as ___________________________________________ _________________________________________ Propel substances on a definite tract or pathway Spindle shaped and uninucleate Stomach,bladder,and respiratory passages • Scant endomysium • Most often in 2 layers-one running circularily and one running longitudinallyalternately contract or relaxing changing size and shape of organ Cardiac Muscle • • • • Only in heart Forms most of heart walls ________________________but involuntary Cushioned in bundles w/ small amount of endomysium striated • When heart contracts,internal chambers get smaller,forcing blood into arteries leaving heart • Branching cells joined by junctions___________________________________These traits and spiral arrangement of bundles allow heart activity to be closely coordinated,giving steady contraction rate • ______________________can shift heart into “high gear” Nervous system Intercalated discs ****** We focus mostly on skeletal muscle here! Muscle Functions – – – – movement _______________________as a result of muscle contraction;quick response to environment Maintaining _____________-maintain erect posture despite gravity Stabilizing ________________-esp. w/ poorly fitting articulating surfaces as in shoulder _________________________________-by –product of muscle activity;ATP used for contractions and ~40% released as heat to mostly maintain normal body temp for at least 40% of body mass posture Generating heat joints
