EX 14

Skeletal MuscleMost numerousVoluntaryStriatedGives you shape, allows for facial

expressions, movement, and manipulation

Cells of the Skeletal Muscle Long cylindrical cells called fibers Multinucleated Composed of myofibrils

Myofilaments○ Made of actin and myosin alternating to

produce the banding pattern (I and A bands)

Sacrolema- “plasma membrane” Sacroplasm- “cytoplasm”

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Skeletal Muscle Fibers

Figure 10–2a The Formation of a Multinucleate Skeletal Muscle Fiber.

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Skeletal Muscle Fibers

Figure 10–2 The Formation of a Multinucleate Skeletal Muscle Fiber.

SarcomeresContractile unitsMade up of bundles of myofibrilsExtend from middle of I band to middle of

next myofibril

Organization of Skeletal Muscle Cells into Muscles Endomysium – areolar connective tissue

sheath that covers muscle fibers Perimysium – encloses sheathed

muscle Fascicle-bundle of perimysium Epimysium-bundle of fasciles Epimysium blend into deep fascia Fascia blends into tendons

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Skeletal Muscle Structures

Figure 10–1 The Organization of Skeletal Muscles.

Tendons provide durability and conserve spaceProvide route of entry for blood vessels

Neuromuscular Junction

Junction between a nerve fiber and a muscle cell

Axons stimulate many muscle fibers Both neuron and muscle fibers make up

the motor unit Neurotransmitters cause a change in Na

and K concentration which causes muscle contraction