Ex Phys Study Guide Test 3 Q A 1 A skeletal muscle fiber that contains a large number of mitochondria is likely to Be capable of sustained or prolonged activity 2 Elite endurance athletes will most likely Possess a greater percentage of type I fibers 3 What is the sequence of processes related to the excitation contraction Ca2 signals synaptic vesicles to Ach into neuromuscular junction coupling EC Coupling Action potential reaches end of motor neuron Ach binds to nicotinic receptors Action potential carried down the T Tubules Actin and myosin bind to form cross bridges SR release Ca2 into the cytosol Four Ca2 ions to troponin C Causing tropomyosin to be pulled off of the cross bridge binding site 4 What would you expect to be most characteristic of an elite Olympic weight lifter High concentrations of anaerobic enzymes for immediate energy pathways 5 Describe satellite cells They divide and fuse to muscle fibers in response exercise induced release of growth factors e g MGF IGF 1 They donate nuclei to a muscle fiber for muscle fiber growth to continue They are NOT always activated 6 If an individual was to lift a load 100 of their 1 repetition maximum what can you assume about motor unit recruitment with respects to the size principle Type I IIa and IIb x motor units are recruited and activated 7 Describe the sarcoplasmic reticulum and t tubules The t tubules are invaginations in a muscle fiber which carry an action potential to the inside of the fiber 8 Resistance training appears to result in an increase in muscle cross sectional area This would have what effect It would increase the diffusion distance for O2 between the capillaries and the mitochondria inside of the muscle cell 9 Describe type I fibers Generates energy for contraction primarily via aerobic metabolism Has a high mitochondrial content Resistant to fatigue 10 Describe the Plasma Membrane Additional thick elastic membrane found just beneath the basement membrane true cell boundary At a muscle fiber s resting length the plasma membrane has the morphological characteristic of small indentions termed caveolae provide additional length during fiber stretching It is semi permeable to proteins solutes and other metabolites It is involved in propagating an action potential that will lead to muscle contraction 11 Infant botulism floppy infant syndrome is associated with Neurotoxins that disrupt Ach synaptic vesicle fusion with the axolemma thus inhibiting exocytosis 12 Describe exercise and its regards to EC Coupling Evident increase in the mRNA protein expression of DHPR in GAS muscles mice following a 15 wk low intensity aerobic exercise program After Resistive Vibration Exercise RVE during 56 day bed rest BR RyR1 relative fluorescence intensity was significantly increased in both type fibers of both muscles 13 Describe Sarcopenia A progressive loss of muscle tissue after the age of 50 The loss of muscle fibers with age A decrease in strength 14 Sarcopenia can be blunted or partly reversed by The use of resistance training 15 Describe the mechanical Coupling Hypothesis It explains the interaction of DHPRs with SR Ca2 release channels RyR1s during EC coupling in skeletal muscle 16 Describe muscle dystrophy Group of genetic hereditary muscle diseases that cause progressive muscle wasting and weakness Duchenne muscular dystrophy DMD is the most common form and is characterized mutations which lead to the absence of dystrophin Becker s muscular dystrophy BMD is the second most common form and is characterized by mutations of dystrophin with abnormal weight shape 17 Describe the size principle Motor units are recruited in order from smallest to largest according to the force demands of the activity 18 Describe the relationship between troponin and tropomyosin Calcium release from the SR binds to troponin which moves tropomyosin off of the actin binding site for myosin 19 What is NOT a function of Ca2 ions during EC coupling Activates satellite cells during exercise to facilitate muscle growth 20 Type motor units produce the lowest maximum force whereas type motor units produce the greatest maximum force I IIb x 21 According to the Sliding Filament Theory how does muscle SHORTENING occur The thin filaments move along the thick filaments pulling the Z lines closer together 22 What is necessary for actin and myosin filaments to bind and form a cross bridge ATP must be hydrolyzed to ADP Pi Tropomyosin must be moved off of the cross bridge binding sites Ca2 2 must be present and bound to troponin C 23 Describe the myonuclear domain theory A muscle fiber can only expand to a limited size unless new nuclei are added to the fiber 24 To terminate muscle contraction what must occur Ca2 must be released from troponin C and pumped back into the SR 25 What best describes why force tension development decreases when the muscle and sarcomere is completely stretched There is little or no overlap between the myofilaments T F 1 The sliding filament theory proposes that a muscle shorten or lengthens because the protein filaments slide past each other while simultaneously changing their individual lengths FALSE 2 Resistance training may increase the size of a whole muscle by the hypertrophy of individual muscle fibers TRUE 3 Muscle growth increases optimally with heavier loads that only allow for 15 repetitions FALSE 4 The length and tension relationship suggests that a shorter sarcomere length optimizes force tension production FALSE 5 Sprinters would most likely have a high production of type I muscle fibers if they are going to have success in their sport FALSE 6 Myosin ATPase has the fastest catalytic rate of ATP in type IIa fibers FALSE 7 Contraction force is greatest in type IIx fibers because of a larger number of mitochondria FALSE 8 The MHC component exists as a multi gene family several different genes specifically encode distinct MHC protein molecules called isoforms TRUE 9 Satellite cells are located on the inside of the basal lamina basement membrane as well as the sarcolemma plasma membrane FALSE 10 When lifting lighter loads and a large force production is unnecessary a neuron is capable to selectively activate only some of the innervated fibers within the motor unit FALSE 11 Type I fibers have a greater number of mitochondria which contributes to an increase in anaerobic capacity FALSE 12 A single sarcomere runs the entire length of the muscle fiber FALSE Videos Muslce Contraction http www youtube com watch v InIha7bCTjM
View Full Document
Unlocking...