local anesthetics

[ctizzle13498]

can someone explain the whole order of blockage when using a local anestetic. Also, the order of loss in dealing with fibers.

Is it saying that pain is a small myelinated fiber and is lost first and blocked first?

Confused thoroughly

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[jfgavina]

local anesthetics act by blocking activated Na channels (remember lidocaine which also is antiarrhythmic in the class IB). small fibers are blocked before large fibers and myelinated fibers are blocked before unmyelinated fibers. but remember that size prevail over myelinization (size matters LOL) so:


small myelinated > small unmyelinated > large myelinated > large unmyelinated

small myelinated fibers carry pain sensation so that's why it is lost first. pain>temperature>touch>vibration, I don't don't know if any of these senses correlates with the other fibers, if someone knows I'd appreciate clarification as well.

 

[ctizzle13498]

Oh got it! Thanks! That makes sense. I'm trying to learn psych and neuro drugs tonite! Hopefully they show up on the exam!

 

[jfgavina]

I'm not religious but please pray for bioch not showing up hardcore on my exam. I can handle biochemical diseases but pathways, oh god.. I never had biochemistry in my whole life

 

[ctizzle13498]

I HATE metabolism of biochem. I could do genetics ALL day!

 

[pbnj003]

I'm not religious but please pray for bioch not showing up hardcore on my exam. I can handle biochemical diseases but pathways, oh god.. I never had biochemistry in my whole life

I know ur exam is coming up soon! but if you are not TOO tight on time in terms of other stuff and want to quickly brush up on biochem pathways, and of course thats assuming that ur "weak" in it and not completely unknown to the subject I would HIGHLY recommend the Kaplan Biochem chapters/videos. I think Seastone does a GREAT job of explaining the pathways. At the most itll take a few hours out of your day, might be worth it.

 

[jfgavina]

I have less than 2 weeks left, too late now i saw it it is 20 hours would take ages to complete.. But thanks! I will do rapid review bioch hy notes (margin notes like the path book ) the dit guy said to not get too bogged down in it but everyday i listen stories.. I had 60% cumm though on uworld, it my weakedt but i guess it isnt that bad. Maybe will put my score 2-3 points below of what it should be if i had studies it right

 

[ctizzle13498]

lower extremity nerves:

is first aid enough?

 

[jfgavina]

I googled sacral plexus just in case. But no idea