Module 3.2Notes - Module 3.2: Skeletal Muscle Structure and...

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Module 3.2: Skeletal Muscle Structure and Function Muscle Specialization - Smooth – involuntary muscle , controlled by the ans(no striations), located in the walls of blood vessels and throughout internal organs. - Cardiac –controlled by the ans and enodrine systems, located on in the heart - Skeletal voluntary muscle , controlled consciously by the somatic nervous system.more than 400 diff skeletal muscles in the body. Primary function = conversion of electric signals to mechanical, creates force production for locomotion, creates force production for postural support, creates force production for breathing, creates heat production for breathing Skeletal Muscle Structure= • The mechanical movement of the muscles strain the connective tissues,which transfers force to the tendon which moves the bone.• Epimysium– “Epi” meaning on top of Surrounds entire muscle• Perimysium – “Peri” meaning around – Surrounds fascicles(bundles of muscle fibers-----endomysiummysium – “inside”meaning internal –Surrounds individual muscle fibers Individual Muscle Fiber • Each muscle fiber is a single muscle cell or _myocyte_• In Skeletal Muscles, myocytes are multinucleate(multi nucleus).• The sarcolema_ is the cell membrane of a myocyte.• The _sarcoplasm_ is the cytoplasm of a myocyte.• Note: The prefix “sarco” refers to flesh• Sarcoplasmic Reticulum – Releases calcium ions during muscle contraction. Absorbs calcium ions during relaxation• tranverse tubules – Run perpendicular to the myofibril. Major site for the coupling of excitation and contraction. Open to extracellular fluid. • Myofibrils – Contain contractile proteins. Myofibrils= basic nit of muscle, contractile proteins are organized into thin filaments and thick filaments, which repeat along the length of the myofibril in sections called sacromeres. Sacromeres= have specialized arrangement of actin and myosin filaments, which run in parallel to each other along the length of the muscle fiber. Actin(thin)-provides binding sites for MYOSIN(thick)-long fibrous tail and globular heads which binds to actin Sliding Filament Theory= muscle fibers shorten when myosin protein filaments pull together actin protein filaments, calcium dependant:focus on actin. the SR releases calcium into carcoplasm. The calcium binds to tropomyosin unlocks tropomyosin from the blocking the binding sites on actin.
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This note was uploaded on 01/12/2012 for the course KIN 173 taught by Professor Staff during the Fall '11 term at Michigan State University.

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Module 3.2Notes - Module 3.2: Skeletal Muscle Structure and...

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