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Ch8 Muscular System

Ch8 Muscular System - The Muscular System The Muscular...

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1 The Muscular System The Muscular System Functions of Muscle square4 Produce movement square4 Maintain posture square4 Stabilize joints square4 Generate heat square4 Prefix myo and mys refer to muscle square4 Prefix sarco refers to flesh Characteristics of Muscles 3 basic muscle types in the body square4 Smooth muscle square4 1 nucleus; no striations; involuntary square4 found mainly in the walls of hollow organs square4 Cardiac muscle square4 usually 1 nucleus; striations; involuntary square4 found only in the heart square4 Skeletal muscle square4 multinucleate; striated; voluntary square4 attached by tendons to bones square4 surrounded & bundled by connective tissue Muscle Fibers square4 Muscle fiber = muscle cell square4 Fascicles = bundles of muscle fibers square4 A muscle fiber consists of myofibrils (many filaments) square4 Each myofibril is made of 2 kinds of proteins filaments square4 Actin filaments: are thin & light square4 Myosin filaments: are thick & heavy square4 Contraction of muscles is due to the movement of these protein filaments Connective Tissue Wrappings of Skeletal Muscle square4 Endomysium = square4 around a single muscle fiber square4 deepest layer square4 Perimysium = square4 around a fascicle of fibers square4 Epimysium = square4 covers the entire skeletal muscle square4 Fascia = square4 on the outside of the epimysium Skeletal Muscle Attachments square4 The epimysium blends into a connective tissue attachments , which may be a/an: square4 tendon = cord-like structure square4 aponeuroses = sheet-like structure square4 Sites of muscle attachment : square4 Bones & cartilages, and square4 connective tissue coverings
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2 Structure of Muscle Fiber square4 Sarcolemma = specialized plasma membrane square4 Nuclei are just beneath the sarcolemma square4 Sarcoplasmic Reticulum (SR)= square4 specialized smooth endoplasmic reticulum square4 stores calcium (Ca++) needed for muscle contractions Structure of Muscle Fiber square4 Sarcomere = contractile unit of muscle square4 alternating bundles of actin & myosin filaments give a striated appearance square4 Cross bridges = paddle-like extension of the myosin filament for attachments to actin filaments square4 Myosin and actin overlap somewhat square4 at rest, there is a bare zone that lacks actin filaments Nerve Stimulus to Muscles square4 Skeletal muscles must be stimulated by a nerve(a motor neuron) to contract square4 Motor unit is composed of: square4 1 neuron + the muscle fibers stimulated by that neuron Neuromuscular Neuromuscular Junction Junction square4 An association site of the motor nerve and muscle cell membrane Neuromuscular Junction Terms square4 Motor end plate = receiving muscle cell membrane square4 Synapse = a point of communication between cells square4 Synaptic cleft = gap between cells square4 nerve & muscle do not make contact square4 filled with interstitial fluid square4 Synaptic vesicle = vesicles at the end of the motor neuron containing neurotransmitters Neuromuscular Junction Terms square4 Neurotransmitter
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Ch8 Muscular System - The Muscular System The Muscular...

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