local anesthetics Flashcards
which LA is manufactured as a single enantiomer
ropivicaine (pure S enantiomer), less neuro toxicity and cardio toxicity than its racemic mixture
which LA is manufactured as a single enantiomer
ropivicaine (pure S enantiomer), less neuro toxicity and cardio toxicity than its racemic mixture
where is
epineurium
perineurium
endoneurium
ID parts of the axon
a alpha
myelination
function
diameter
velocity
block onset
myelination: heavy
function: skeletal muscle- motor proprioception
diameter: 12-20
velocity: +++++
block onset: 4th
a beta
myelination
function
diameter
velocity
block onset
myelination: heavy
function: touch, pressure
diameter: 5-12
velocity: ++++
block onset: 4th
a gamma
myelination
function
diameter
velocity
block onset
myelination: medium
function: skeletal muscle- tone
diameter: 3-6
velocity: +++
block onset: 3rd
a delta
myelination
function
diameter
velocity
block onset
myelination: medium
function: fast pain, temperature, touch
diameter: 2-5
velocity: +++
block onset: 3rd
b fibers
myelination
function
diameter
velocity
block onset
myelination: light
function: preganglionic ANS fibers
diameter: 3
velocity: ++
block onset: 1st
C sympathetic
myelination
function
diameter
velocity
block onset
myelination: none
function: post ganglionic ANS fibers
diameter: 0.3-1.3
velocity: +
block onset: 2nd
C dorsal root
myelination
function
diameter
velocity
block onset
myelination: none
function: slow pain, temperature, touch
diameter: 0.4-1.2
velocity: +
block onset: 2nd
LA’s inhibit peripheral nerves in the following order
B fibers > C fibers > small diameter A fibers > large diameter A fibers
LA’s can bind to VG channels in which states
active and inactive states
LA’s bind to which subunit on VgNa channel
alpha
describe resting state
-70mV, channel is closed
describe active state
-70 to +35mV
when threshold potential is reached, channel opens
open channel allows Na to follow concentration gradient (outside to inside)
describe inactive state
channel is closed
inactivation gate plugs channel until RMP is re established
restoration of RMP converts channel from inactive state to resting state. at this point, the nerve is ready to be stimulated again
what do LA’s do to RMP and TP
have no effect on TP and RMP
3 things that influence RMP
- chemical force (concentration gradient)
- electrostatic counter force
- Na/K/ATPase (3 Na out for every 2 K in)
what does decreased serum K do to RMP
becomes more negative
what does increased serum K do to RMP
becomes more positive
TP and primary electrolyte
-55, Ca2+
repolarization
occurs when K leaves the cell or Cl- enters the cells
cell is resistant to subsequent depolarization during during refractory period because Na channels are in the closed inactive state
henderson hasslebach equation