Local Anesthetics Flashcards
(26 cards)
Local anesthesia can be accomplished by many substances such as
amines, alcohols and many toxins
Pressure on nerve endings can result in
Anesthesia
What is the prototype local anesthetic
Cocaine
What plant in the Andes mountains does cocaine come from?
Erythroylon Coca
Who isolated the pure alkaloid in 1860?
Albert Niemann
Who in 1884 completed the first study reporting it’s value as a stimulant, treatment for ETOH and MSO4 addiction, antiasthmatic, local anesthetic and aphrodisiac
Sigmund Freud
What was the first synthetic LA?
Procaine- made in 1905 by Einhorn
What was the first amide anesthetic?
Dibucaine 1932
When was Tetracaine first used?
1930
When was lidocaine first sythesized?
1943 by Lofgren
How is a nerve action potential generated?
Following an increase the permability of the membrane to sodium ions
How do LA’s work?
Local anesthetics produce a reversible, dose-dependent blockade of sodium ion influx into nerve cytoplasm.
What is an Axon
functional unit of the nerve
What is an axolema
The nerve cell membrane
What is the axoplasm?
the intracellular components
What do Schwann cells do?
surround, support, insulate axon
What is a fascicle?
A bundle of axons
What is the endoneurium?
layer of delicate collagen tissue around axon embedding it in the fascicle
What is the Perineurium
Over-lapping group of cells binding fascicles
What is the Epineurium?
Layers of connective tissue around fascicles These layers must be penetrated by LA to produce it’s effect
What is Myelin?
liquid substance containing proteins and lipids, forms insulating layer around some nerves. Basically prevents current from leaking out of nerve.
What are nodes of Raniver?
small, unmyelinated segments between Schwann cells. Contain large numbers of Na channels allowing intense APs which can “jump” from node to node. (saltatory conduction)
What is important about the nodes of Ranvier and diffusion of LA’s?
Limited diffusion barrier at the nodes of Ranvier= Primary site of LA action
Is a nerve blockade concentration dependent?
Yes- It ends when the concentration of LA falls below a minimum effective point Requires disruption of several, contiguous channels
