VPHY EXAM 2 - MUSCLE PHYSIOLOGY QUESTIONS AND ANSWERS SOLVED CORRECTLY

VPHY EXAM 2 - MUSCLE PHYSIOLOGY QUESTIONS AND ANSWERS SOLVED CORRECTLY what controls the skeletal muscles? - Answers somatic motor system 3 muscle types - Answers - smooth - cardiac - skeletal 5 categories of skeletal muscle function - Answers - movement - support - posture - temperature regulation - communication the two parts of myofilaments - Answers - myosin - actin what gives the skeletal muscle its rod appearance? - Answers myocyte/muscle cell what gives the skeletal muscle its striped appearance? - Answers myofilament parts motor unit - Answers a single motor neuron and all of the muscle cells (fibers) it innervates how many muscle cells does a typical motor neuron innervate? - Answers 100-1000 muscle cells! a muscle is comprised of one or many motor unit(s) - Answers many are all muscle fibers in the same motor unit the same or different type? - Answers same type! NMJ (neuromuscular junction) - Answers specialized synapse between the somatic motor neuron's nerve terminal and the motor end plate of the skeletal muscle cell what sends the signal in the neuromuscular junction - Answers somatic (alpha) motor neuron what recieves the signal in the neuromuscular junction - Answers skeletal muscle cell E/C coupling - Answers - excitation/contraction coupling - transformation of the electrical signal in the muscle cell into contraction of sarcomeres what kind of receptors are on the motor end plate in the neuromuscular junction? - Answers nicotinic 9 steps from motor neuron APs to skeletal muscle contractions - Answers 1. ACh binds to skeletal muscle fiber 2. AP moves into T-tubules 3. sarcoplasmic reticulum releases Ca2+ 4. Ca2+ binds troponin; active cross-bridge cycling 5. skeletal muscle contraction 6. acetylcholinesterase degrades ACh 7. Ca2+ pumped into ECF and SR 8. tropomyosin blocks cross-bridge formation 9. skeletal muscle contraction is pervented the firing of motor neuron's AP leads to - Answers contraction of muscle cell what causes muscle contraction - Answers the Ca2+ release from the SR after Muscle APs are sensed in the T-tubules parts of the sarcolemma - Answers - t (transverse)-tubules invaginate the myofibrils - t0tubules are continuous with the sarcolemma sarcoplasmic reticulum surrounds - Answers myofibrils what carries the AP does the T-tubules - Answers Na+ channels what activates the Na+ channels in a muscle cell - Answers EPSP are skeletal muscle cells long or short - Answers long what are the sarcoplasmic reticulum calcium release channels called - Answers ryanodine receptors (RyRs) what are the transverse tubule voltage-gated calcium channel called - Answers dihydropridine receptors (DHPRs) what do the transverse tubule voltage-gated calcium channel do - Answers - act as voltage centers - physically opens Ca2+ receptors How does a larger motor unit differ from a smaller motor unit? - Answers a large motor unit innervates many more muscle fibers where do the upper motor neurons of all direct (pyramidal) tracts originate? - Answers motor