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32 Cards in this Set
- Front
- Back
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local anesthesisa is the transient loss of ___,____,____ funchtion
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sensory, motor, autonomic function
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local anesthetics are drugs that produce
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reversible conduction blockade of impulses along central and peripheral nerve pathways
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Local anesthethetics bind ____channels in the _____state
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Na, inactivated
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Local anesthetics prevent transmission of nerve impulses by inhibiting passage of ___ion sel. na chan
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sodium
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do local anesthetics bind to na channels in the active or inactive state?
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inactive
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what do local anesthetics do to the resting and threshold potential
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nothing
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what do local anesthetics do to rate of depolarization?
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decreases
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what does blocking of na channels do?
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prevents achievement of threshold potental.
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In addition to sodium ion channels, local anesthetics block
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potassium ion channels
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Cm is
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the minimum conentration of local anesthetics nec to produce condiction blockade of nerve impulses
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How do nerve fibers influence Cm?
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larger nerve fibers require higher concentraions of local anesthetic for conduction blockade
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what does high pH do to Cm?
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lowers it
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what does high frequency of nerver stimulation do to Cm?
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lowers it
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how does Cm of skeletal muscle compare to sensory fibers?
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cm of skeletal fibers 2X that of sensory fibers, so sensory anesthesia may not always be accompanied by skel mus. an
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which requires less local, subarachnoid or epidural?
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subarachnoid b/c greater access to unprotected nervers in subarachnoid
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order of magnitude of blockade
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autonomic>sensory>motor
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will a spinal block cause more motor or autonomic blockade?
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autonomic
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are ;pca; anesthetics weak bases or acids?
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bases
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how does myelenation affect local anesthetics
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more mylenated, the better it works
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Local anesthetics have pKa slightly ____physiological pH
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above
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what does acidosis do to ionization of local anesthetics?
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increases ionization fraction majung it poorer quatlity in acidic environment
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what determines if it is an ester or amide?
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bond linking the hydrocarbon and lipophilic aromatic ring.
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important differece between ester and amide is
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site of metabolism and potential to produce allergic rxs.
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whic part is lipophillic?
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benzene ring
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which part is hydrophyllic?
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tertiary amine
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which portion is essential to anesthetic action..lipophyllic or hydrophyllic?
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lipophillic(unsaturated aromatic ring)
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if allergic to sunscreen could be allergic to
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esters (PABA)
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amides are primarily metabolized in the
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liver
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how are esters metabolized?
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hydrolysis by cholinesterase in the plasma
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how does threshold potential compare to resting potential?
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threshold (-55) and resting (-70)
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when local anesthetics bind to inactivated Na channels, what happens?
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prevention of achievement of threshold potential prevents achievement of threshold potential.
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Are Esters or Amides generally more potents?
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esters
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