Term
| What is the order of cells being produced during myogenesis? |
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Definition
| somites of embryo -> myoblast -> myotube ->fibril packed myotube -> migration of nuclei to periphery and structural organization |
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Term
| What cells fuse together to form myotube? |
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Definition
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Term
| What are myotubes surrounded by? |
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Definition
| enclosed by basement membrane or basla lamina w/ multinuclei, which are centrally located. |
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Term
| How are additional myoblasts generated? |
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Definition
| they aggregate beneath basal lamina using primary myotube as scaffolding to become secondary myotube and unfused myoblasts. Actin and myosina re formed and organized. progressive filling of cell with contractile proteins are from outside to inside. Nuclei migrate to periphery of cell from center. Primary and secondary are separated & become mature fibers. |
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Term
| What are Myt-5 and MyoD responsible for? |
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Definition
| Conversion of a cell in somite to a myoblast. |
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Term
| What are myogenin and MRF4 responsible for ? |
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Definition
| Conversion of the myoblast to the differentiated myocyte. |
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Term
| What are the primary and secondary Myogenic Regulatory factors? |
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Definition
| Primary- Myt-5 and MyoD. Secondary- Myogenin and MRF4 |
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Term
| What happens as a result of lack of MyoD and Myf-5? |
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Definition
| No skeletal muscle and apparently no myoblasts. lack of myogenin have little skeletal muscle as fibers fail to differentiate. |
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Term
| What occurs with a lack of myogenin? |
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Definition
| have little skeletal muscle as fibers fail to differentiate. |
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Term
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Definition
| refers to the formation of synapse between the nerve and the muscle fiber. |
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Term
| How is it that every muscle fiber has only one motoneuron? |
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Definition
| one motoneuron survives after competition with many other neurons. |
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Term
| What is the action of agrin? |
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Definition
| cause clustering of acetlcholine receptors. |
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Term
| What are the actions of MuSK and rapsyn? |
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Definition
|
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Term
| 4 pathways of synapse elimination |
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Definition
| Blocking electrical activity: slows elimination. Blocking mechanical activity: slows elimination. Electrical stimulation: accelerate elimination. Blocking Acetylcholinesterase: acellerate elimination. |
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Term
| 4 pathways of synapse elimination |
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Definition
| Blocking electrical activity: slows elimination. Blocking mechanical activity: slows elimination. Electrical stimulation: accelerate elimination. Blocking Acetylcholinesterase: acellerate elimination. |
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Term
| What are the 3 components of connective tissues? |
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Definition
| Epimysium, Perimysium, Endomysium. |
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Term
| Membranous Structures of Muscle Fiber. |
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Definition
| Sarcoplasmic Reticulum, T-tubule. |
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Term
| What are the 3 myofibrils? |
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Definition
| Actin, Myosin, Other regulatory proteins. |
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Term
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Definition
| outermost layer that surrounds entire muscle. |
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Term
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Definition
| the layer that surrounds the bundle of several individual msucel fibers called fascicle. |
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Term
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Definition
| the layer that surrounds each individual muscle fiber. |
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Term
| What is the primary component of the connective tissues? |
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Definition
|
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Term
| What strucutre lies beneath the endomysium that encloses the muscle fiber? |
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Definition
|
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Term
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Definition
| It is the muscle plasma membrane. Lipid bilayer( 60% protein, 20% phospholipd and 20% cholesterol). T-tubule:invagination of sarcolemma, carrying AP to an interior of muscle. |
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Term
| Where are satellite cells located? |
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Definition
| Between basal lamina and sarcolemma. |
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Term
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Definition
| Membranous network in sarcoplasm, surrounding each myofibril & running parallel with myofibril. |
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Term
| What are terminal/ lateral cisternae? |
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Definition
| enlarged portions of SR. store large amount of Ca2+. |
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Term
| What structure does the Sarcoplasmic surround? |
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Definition
| T-tubule is surrounded by Sarcoplasmic cisternae. occurs at the junction of A-band and I-band. |
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Term
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Definition
| produce ATP. More # in slow twitch fibers than fast fatigable fibers. increase size and # in rsponse to physical exercise, especially endurance type of training. |
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Term
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Definition
| thin filament: actin filament , thick filament: myosin filament. |
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Term
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Definition
| consists of actin, a globular molecule. a-helical arrangment of actin filaments. contains binding sites for myosin. regulte tension generation. |
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Term
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Definition
| rod-shaped molecule. sits on the grooves of actin filaments. covers myosin binding sites of actin at rest. |
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Term
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Definition
| spherical molecule. Tn-I: inhibitory effect on tropomyosin. Tn-C: binds w/ Ca2+. Tn-T: binds troponin to ropomyosin. |
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Term
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Definition
| rod-shaped molecule. 1 nebulin/ thin filament. serve as a template for formation of thin filament. |
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Term
| Myosin Filament structure |
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Definition
| Each molecule consists of 6 polypeptide chains: 2 heavy chains and 4 light chains. |
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Term
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Definition
| rod-shaped molecule, heavy meromyosin: two globular head regions. S1.S2. Light meromyosin: tail region. |
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Term
| What portion of the myosin filament contains ATPase activity? |
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Definition
| The head of the myosin filament contains ATPase activity. Resulting in liberation of energy for movement of actin. |
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|
Term
| Light chain structure of Myosin |
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Definition
| function not clear. structural support for S1 head. influence the speed of contractino of myosin heavy chain. |
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Term
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Definition
| Also called connectin. 3 million daltons. Stretches entire length of half a sarcomere from M-line to Z-line. I-band portion of titin contains the elastic region. immunoglobular domain. PEVK domain. P:proline. E:glutamate. V:valine; K: lysine |
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Term
| What happens during low force and high force stretches of titin? |
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Definition
| low force stretch: Ig-domain is stretched. high force stretch: PEVK-domain is stretched. |
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Term
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Definition
| Provides the sarcomere with a structural framework through association w/ many other myofibrillar & cytoskeltal proteins. is likely involved in signaling processes since it binds to various proteins w/ a role in sarcomere assembly and turnover. main player in determining passive muscle tension. |
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Term
|
Definition
| located parallel to the actin filaments, spanning teh length of actin filaments. remains fixed as the sarcomere is stretched. anchored at the Z-line, binding to alpha-actinin. Function: regulates the assembly and final length of the actin filament. complex of nebulin and calmodulin modulates msucel contraction. |
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Term
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Definition
| found in M-line. helps titin and myosin maintain their 3-dimensional structure. |
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Term
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Definition
| binds to myosin. maintains the width of the thick filaments. |
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Term
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Definition
| binds to the thick filament and phosphorylates the light chain of the myosin. This causes the sensitization of the myosin to Ca2+ activation. |
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Term
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Definition
| interconnects adjacent myofibrils. maintains structureal & functional integrity of muscles. desmin null mice. muscle damage w/ the signs of instability & disintegration. disruption of muscle architecture w/ degeeration. |
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Term
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Definition
| Excitation-Contraction Coupling. Change in muscle length during action. |
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Term
| Initiation of Muscle Action |
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Definition
| impulse generation and propagation through nerves. Neuromuscular junction transmission. Excitation-contraction: excitation of muscle fibers, muscle contraction. |
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Term
| What are the steps of excitation-contraction coupling? |
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Definition
| Muscle action potential propagation. Ca2+ release from SR. Ca2+ binding to troponin. Interaction of myosin head and actin. Cross brdige moves: tension. Ca2+ taken up to SR by Ca2+ ATPase. Ca2+ removal from troponin. Relaxation. |
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Term
|
Definition
| Dihydropyridine Receptors. |
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Term
|
Definition
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Term
| Skeletal Muscle: Mechanical Coupling |
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Definition
| DHPR: voltage sensor. voltage induced relase of Ca2+ through the RyR channel from the SR membrane. |
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