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25 Cards in this Set
- Front
- Back
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Einhorn |
In 1905 introduced first SYNTHESIZED local anesthetic (Procaine/Novocaine) |
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Local Anesthetics |
Drugs that produce a REVERSIBLE conduction blockade. |
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Sodium ethyl-enediamineteracetic acid (EDTA) |
Antioxidant added to local medication to prevent breakdown in commercial preparations. |
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Optical (entantiomer) |
Mirror image of each other that is not superimposable EX Human Hand |
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Chiral Molecules |
Asymmetrical(direction of configuration helps to categorize the isomer)
Such compounds rotate plane polarized light either to the right (D or+) or to the left (L or -) |
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Racemic mixtures |
Donot rotate light; they have relatively equal amounts of 2 isomers.
Rotates light based on how heavy the molecule |
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Ropivacaine |
Pure–S(-) enantiomer not a racemic mixture
ADVANTANGES Lesstoxicity for cardiac tissue Greaterspecificity for sensory nerves than motor nerves. Less motor block |
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Locals |
· Locals produce their clinical effects byinterfering with electrical activity in the nervous system· Their primary action is to inhibit thepropagation of nerve impulses in peripheral nerves and in the spinal cord· Locals may act directly on the sensory endingsof nerves when applied topically· Locals may inhibit synaptic transmission in thespinal cord when used epidural or intrathecal
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endoneurium
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Eachindividual axon is intimately surrounded by non-glial cells
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Neuron or nerve cells |
sensory afferent, motor efferent, orinterneurons(internuncial)which conduct impulses from sensory to motor neurons simplistically, neuronsrespond to stimuli by transmitting nerve impulses.
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Axolemma |
A continuous sheath around the segmented myelin sheath.
It is derived from Schwann cells and plays an essential part in peripheral nervefiber regeneration The brain and spinal cord do not have aneurilemma and are not known to regenerate |
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Nodes of Ranvier |
Separatingthe myelinated regions are narrow zones that contain the structural elements necessary for neuronal excitability.
Interruptions in the myelin allowing current regeneration. High concentrations of Na channels are locate here |
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Nodal gap substance |
Located between the nodes of Raniver compoased of gycoprotein and dense negatively charged material. This substance may act as a reservior to bind metal cations and basic drugs. |
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How many Nodes of Ranvier must be blocked to stop nerve conduction?? |
2-3 |
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Nerve axon |
Where are voltage gated sodium channels found |
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Sequence of the blockade |
B fibers, C fiber, A Delta fibers, A Gamma fibers, A Beta fibers, A Alpha fibers "Bad children don't get big allowances." |
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Peripheral nerve fibers SIZE |
Diameter from 0.3 to 22 microns. Axons smaller then one are unmyelinated. They are encased instead by Schwann cell that may cover around five to ten fibers at once. |
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Excitability |
Nerve cells possess this property in which theyrespond to stimuli by undergoing transient physiochemical changes which mayalter the resting electrical potential of the cell and initiate a nerve impulse
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Neural membrane contains voltage difference of |
(+60) innner to (-90) outer |
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Locals have an increased affinity with... |
Open (activated) and inactive states (stabilize the Na+ channels) |
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Ionized or hydrophilic portions bind to Na channels preventing their opening..... |
H-gate |
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MOA of locals |
It isspeculated that local anesthetic agents bind to specific sites located on the inner portion of the sodium channel (internal gate or H-gate) aswell as obstructing these channels near their external openings.
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Frequencydependent local anesthetic blockade
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mostlocal anesthetics produce a much greater degree of nerve blockade at higherdegrees of firing
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phasic or use-dependent block
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An increase in the stimulus frequency increases the degree of block--use or frequency dependent block.
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