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12 Cards in this Set
- Front
- Back
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What ion does the GABAa receptor increase the conductance of? GABAb?
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chloride; potassium
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What is the concept of accommodation in regards to hyperkalemia?
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While depolarization opens Na channels, it also causes closure of the Na channel inactivation gate. In hyperkalemia cells are depolarized to threshold but action potentials aren't occurring because the Na inactivation gate is closed. This causes muscle weakness in addition to other effects
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What is the equation for intracellular membrane potential?
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E=-2.3(RT)/(zF)log(Ci/Co)
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What is the equation for effective osmotic pressure (v osmolarity)?
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pi=g(C)(RT)(refl. coeff)
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What is the equation for membrane flux? what affects permeabilty?
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J=-PA(C1-C2); P is affected by membrane thickness, oil/water partition coeff, solute radius
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What is the absolute refractory period? relative?
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Absolute= no additional AP during the AP (until repolarization); relative= during the undershoot (close to K potential) it takes higher stimulus to elicit AP.
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The nicotinic receptor allows passage of these ions.
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Na, K, reaching a membrane potential in between (close to zero)
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What is the usual membrane potential for Na? Ca? K? Cl?
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Na=+65mv; Ca=+120mv; K=-85mv; Cl=-90mv
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NO is made from what AA and what enzyme?
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arginine; NO synthase, it is an inhibitory NT in many locations
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How does a skeletal muscle get activated?
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Nicotinic recept->depolarization->T-Tubules->dihydropyridine conform->ryanodine activation Ca release from SR->Ca binds troponin C, Troponin T/I stop tropomyosin inhib->actin-myosin bind->ATP displaces->hydrolysis "power stroke"->ADP released, actin-myosin binds->repeat ATP binding
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How does smooth muscle get activated?
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Depolarization->open voltage gated Ca channels-> opening of SR Ca channels (also by IP3)-> incr. intracell. Ca-> binding to calmodulin-> myosin light chain kinase activation-> phosphorylation of myosin-> myosin binds actin-> cross-bridge cycling (no troponin)
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What is multi-unit SMC? Unitary smooth muscle?
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Multi-unit-little electrical coupling; unitary-high degree of electrical coupling and spontaneous, slow wave, activation (vascular smooth muscle is a combination)
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