Muscles of the body

kshinsky's version from 2017-07-30 18:58

Section 1

Question Answer
types of musclesskeletal, cardiac, smooth
functions of skeletal musclesmaintain posture, skeletal movement, maintain body temp, nutrient storage, support soft tissue, guard the body
layers of skeletal muscleepimysum, perimyisum, endomyisum
epimyisumaround entire muscle
perimyisumdeep of the epimyisum, fibers organized in bundles bound by perimysium
fasiclefibers organized in bundles
endomyisumsurrounds each individual cell, contains myostalletite cells
myostatellite cellsstem cells
skeletal muscle cellsalways mutlinucleated
sarcolemmacell membrane of muscle fiber, surrounds the scaroplasm
sarcolemma includeschange in transmembrane potential, includes sodium potassium pump
resting membrane potentional-70 mv
transverse tubules (t-tubules)deep depressions in the sarcolemma, transmit action potential through cell, allow fiber to contract simultaneously
myofibrilsmade up of myofilaments, responsible for contraction
myofilamentsprotein filament, thin filaments, thick filaments
thin filamentsactin
thick filamentsmyosin
scaroplasmic reticulum (SR)surronds each myofibril
SR functionswhen it receives and impulse it releases calcium ions, when not receiving impulse it stores calcium ions
terminal cisternaechambers in the SR, release calcium
triad1 t-tubule + 2 terminal cistrae
sacromeresonly found in skeletal muscles, repeating arrangement of myofilaments and repeating subunits of myofibers

Section 2

Question Answer
myosin binding sitesite combined strongly to myosin (thick filaments)
tropomyosin-troponin complexshape controlled by presence or absence of calcium
when there is little calciumtropopmyosin-troponin complex covers of the myosin binding site
when it releases calciumit exposes the myosin binding site
thick filamentscontain titan strains that recoil after
thick filaments includes300 twisted myosin filaments, tail, head
tail of thick filamentsbinds other myosin
head of thick filamentsmoves back and forth
myosin actionduring contraction myosin heads pivot and move as a hinge
motor nervedelivers stimuli to muscle fiber or glandular cell
neuromusclar junctionconnection between motor nerve and muscle fibers
neuromuscular junction synapsearea of communication between neruon and muscle fiber
pre synaptic cellcell brining info to the site (motor neuron)
post synaptic cellcell retrieving info (muscle fiber)
nuerotransmitterallows cells to exchange info with pre synaptic and post synaptic cells
acetycholinechemical only released during NMJ
cells at restpositive charge outside, negative charge inside the cell
threshold potentional-55mv
step 1 of contraction cycleThe axons of the nerve cells of the spinal cord branch and attach to each muscle fiber forming a neuromuscular junction.
step 2 of contraction cycleACh binds with the sarcolemma.
step 3 of contraction cycle ACh binds with receptors and opens Na+ channels, Na + rushes in and the sarcolemma depolarizes. The K+ channels open and the region repolarizes
step 4 of contraction cycleCa++ is released from the sarcoplasmic reticulum.
step 5 of contraction cycleStep A: Myosin head attaches to actin. (High energy ADP + P configuration) Step B: Power stroke: myosin head pivots pulling the actin filament toward the center. Step C: The cross bridge detaches when a new ATP binds with the myosin. Step D: Cocking of the myosin head occurs when ATP à ADP + P. Another cross bridge can form.
relaxationcontraction duration, depends on duration of neural stimulus and # of calcium ions in scaroplasm
rigor mortisfixed muscular contractions 24 hours after death, atp runs out make calcium release to contract muscles.
twitch contractionsingle contraction then immeadiate release, 7-100 msec
sustained contractionsrepeating stiumli, ex: tetnus contractions
treppe contractiona stair step increase in twitch tension, repeated stimuli immediately after relaxation phase, <50 sec, causes series of contractions with increasing tensions
wave summationsexceeds nerve impulses >50 sec, repeating stimuli before the end of relaxation occurs
complete tetanusif stimulation frequency is high enough, muscle never begins to relax, and is in continuous contractions

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