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Exam (elaborations)

D515 Exam 4 (NEWEST UPDATED EXAM) with precise detailed solutions

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D515 Exam 4 (NEWEST UPDATED EXAM) with precise detailed solutions

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D515 Exam 4 (NEWEST UPDATED EXAM) with ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




precise detailed solutions ||\\//|| ||\\//||




Skeletal Muscle ||\\//||




attached to bones and skin, voluntary, require nervous system stimulation, contract rapidly,
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




trier easily, powerful, elongated cells/muscle fibers, striated
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Skeletal Muscle Structure ||\\//|| ||\\//||




CT transmits mechanical forces of muscle -> epimysium, perimysium, endomysium
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Epimysium of Skeletal Muscle ||\\//|| ||\\//|| ||\\//||




CT sheath surrounding muscle
||\\//|| ||\\//|| ||\\//||




Perimysium

CT sheath surrounding a fascicle
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Endomysium

CT sheath surrounding each muscle fiber/cell
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Muscle Fiber ||\\//||

,long cylindrical cells with multiple peripheral nuclei, sarcolemma -> cell membrane,
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




myofibril -> contractile element, densely packed rods, gives striated appearance ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Myofibrils

organelles composed of bundles of myofilaments, sarcomeres -> contractile units arranged ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




end to end (portion between 2 Z lines), myofilaments -> filaments made of contractile
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




proteins, thin filament = actin and thick filament = myosin ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Sarcomere Components ||\\//||




A band -> thick filaments including filament overlap, H zone -> midsection of A band
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




excluding overlap, M line -> anchors thick filaments (myosin), I band -> thin filaments ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




(actin), Z line -> sheets of proteins that anchor thin filaments
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Myofilaments

thick -> myosin with head that binds to actin and ATP and polypeptide chain tail, thin ->
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




actin with twisted double strand of actin subunits (tropomyosin and troponin regulatory
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




proteins)




Sliding Filament Model of Contraction ||\\//|| ||\\//|| ||\\//|| ||\\//||




relaxed -> little overlap of filaments, contraction -> thick filaments pull thin filaments
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




toward center for more overlap (Z lines closer and sarcomere shortens, I bands shorten, H
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




zone disappears, A band stays same length but closer together)
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||

,Low Intracellular [Ca2+]
||\\//|| ||\\//||




tropomyosin blocks active sites on actin, myosin heads can't attach to actin, muscle fiber ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




relaxes




High Intracellular [Ca2+] ||\\//|| ||\\//||




1. Ca2+ binds to troponin 2. Troponin changes shape and moves tropomyosin away from
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




myosin-binding sites 3. Myosin heads bind to actin causing sarcomere shortening and ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




muscle contraction ||\\//||




Cross Bridge Cycle ||\\//|| ||\\//||




1. Cross bridge formation 2. Power stroke 3. Cross bridge detachment 4. Cocking of myosin
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




head




Cross Bridge Formation ||\\//|| ||\\//||




first step in cross bridge cycle, energized myosin head attaches to actin myofilament and
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




forms a cross bridge ||\\//|| ||\\//|| ||\\//||




Power Stroke ||\\//||




second step in cross bridge cycle, ADP and Pi are released and the myosin head pivots and
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




bends changing to its bent low-energy states and pulls actin toward M line
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Cross Bridge Detachment ||\\//|| ||\\//||

, third step in cross bridge cycle, after ATP attaches to myosin the link between myosin and
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




actin weakens and the myosin head detaches (without ATP -> myosin heads don't detach -
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




> rigor mortis)||\\//|| ||\\//||




Sarcotubular System ||\\//||




connects nerve impulse to Ca2+ release, includes T tubules and sarcoplasmic reticulum ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




(SR)




T Tubule ||\\//||




part of sarcotubular system, tunnel-like extensions of sarcolemma, allows propagation of AP
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




into cell, surround myofibrils
||\\//|| ||\\//|| ||\\//|| ||\\//||




Sarcoplasmic Reticulum (SR) ||\\//|| ||\\//||




part of sarcotubular system, specialized smooth ER, network surrounding each myofibril,
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




stores and releases Ca2+, terminal cisterns = end dilations ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Excitation-Contraction Coupling Overview ||\\//|| ||\\//||




AP spreads along cell membrane and travels through T tubules, a permeability change is
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




produced in the membranes of the SR which releases Ca2+ from the SR into the cytosol ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




Excitation-Contraction Coupling Steps ||\\//|| ||\\//||




1. AP propagates along sarcolemma and down T tubules 2. Ca2+ released (transmission of
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||




AP along T tubules of the triads opens channnels in terminal cisterns of SR) 3. Ca2+ binds
||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//|| ||\\//||

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