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11 Cards in this Set
- Front
- Back
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what regs contraction of smooth m.?
skeletal m? |
-myosin (reg light chain)
-tropomyosin/troponin on actin |
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where does Ca+ come from in smoth m.?
skeletal m.? |
-extracellular
-SR |
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where is the extra Pi on smooth m.?
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-bound to light chain on myosin
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contraction process of smooth m. (7)
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1. myosin kinase activated
2. it Pi's myosin-ADP(Mg)-Pi complex 3. complex binds actin 4. Actin bumps off Pi, then ADP(Mg) leaves 5. AM-P binds ATP which knocks off Actin (M-P-ATP(Mg)) 6. ATP is hydrolized to M-P-ATP(Mg)-Pi 7. Repeat from #3 5. |
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4 types of Ca+ reg
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1) receptor mechanism: hormone/NT opens gate. chemical.
2) membrane potential dependent channels: respont to APs or even sub-threshold potentials. -GRADED RESPONSE 3) SR receptors: P3 gets cleaved off of membrane (in response to NT or H), binds to and stim's SR 4) Pacemaker reg |
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tonic contraction, potential mediated (4)
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-maintain same force (as stim?) over time
-due to membrane-potential-dependent channels -:. graded response -usually has some deg of tension (never fully relaxed) |
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Tonic contraction, receptor mediated (3)
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-receptor-activated
-inhib/activators can bind to receptor to activate/inactivate Ca+ channels -independent of membrane potential |
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pacemaker property/potential
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-cell can induce spontaneous AP
-neighboring cells become excited ("wave" of excitation) -these cells are scattered w/in m.'s -frequency of APs can be influenced by external factors |
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slow wave
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-cyclic (vs. constantant modulation of pacemaker)
-??? |
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multi-unit smooth m. cells (5)
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-activation of each muscle fiber/cell is required
-minor category of smooth m. -neurogenic initation -hormone modulation -used for moving and holding contraction, eg. iris, vascular s.m., piloerectors, etc |
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single-unit smooth m. cells (4)
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-activation/regulation of 1 pacemaker cell spreads to neighboring cells
-connected by gap junctions -initiated by ANS (NT)(myogenic), modulated by hormone, ANS (NT) -often used to squeeze hollow organ, eg. bladder, gallbladder, GI tract, lymph |
