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4 Cards in this Set
- Front
- Back
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Specialized structur of muscles cells
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1-sarcolemma (cell membrane) responsive to ACh (acetylcholine) a neurotransmitter. Surface can be polarized & depolarized.
2-Sarcoplasmic reticulum-(endoplasmic reticulum)-folded sacs; store and release calcium ions. (Ca++) 3-Sarcoplasm-(cytoplasm)-fluid environment, has stores of glycogen (glucose chains),creatine phoshpate (energy source), myoglobin (holds oxygen) 4- neuromuscular junction- neural ending (axon terminal) lays over sarcolemma with a space between (synapse) NOTE: neurotransmitters diffuse across. (ACh) |
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Part 1
Stages in Physiology of Muscle Fiber Stimuli & Contraction |
1- Action at neuromuscular junction
-action potential at axon terminal -change in permeability: Ca++ enters terminal from interstitial fluid, stimulates... -vessicles of ACh to fuse w/membrane near synapse. -ACh diffuses across synapse to sarcolemma -ACh bonds to receptors on Na+ channels -Na+ moves from outside > inside, initiating depolarization of small region of sarcolemma. |
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Part 2
Stages in Physiology of Muscle Fiber Stimuli & Contraction |
2-Generation of Action Pot...
-movement of Na+(depolarization) affects nearby voltage-regulated ion channels. -VRIC's near synapse open in response, allowing more Na+ to cross membrane. -Depolarization of sarcolemma continues across surface rapidly -When depolarization reaches transverse tubules (t-tubules) the depolarization moves to myofibrils (triad region) -as depolarization reaches sarcoplasmic reticulum it changes permeability of S.R. (to Calcium) -Ca++ is releases > diffused to sarcomeres. |
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advantages of echocardiogrphy
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more sensitive in detecting ischemia
assessment of LV size and fxn dx valvular dz |
