Neurophysiology Flashcards
peripheral neuropathy
pain and dysesthesia
- loss of sensation or reflex;weakness
- fasciculations and paresthesia
mononeuropathy
involve isolated neurons
-trauma or pressure
radiculopathy
damage to nerve roots
polyneuropathy
metabolites, toxins, demyelinateing disease, chronic infections
can affect axon, myelin, or synapse
diabetic neuropathy
hyperglycemia is trigger
- pro-oxidative and pro-inflammatory
- PNS cells more susceptible
- predominantly axonal damage
- variable demyelination
resting membrane potential
-65
synaptic potential
slow, graded, local
action potential
brief, actively propagated and traveling
equilibrium
current of ion moving in and out of cell is equal
–determined by charge and concentration
establishment of RMP
inward Na
outward K
-closer to K - because it has greater permeability
maintained bt Na/K ATPase pump
capacitor
lipid bilayer
-stores charge on opposite sides
resistor
ion channels
-allow certain amount of ions to flow
conductance
flow of ion across membrane
resistance
opposite of conductance
depolarization
due to inward Na current
hyperpolarization
due to outward K current
voltage-gated Na channels
open - membrane depolarization
inactivation - closed and will not reopen
deinactivated or resting - after membrane repolarized, return to conformation that allows them to opened in response to depolarization
voltage gated K channels
open - slowly, response to depolarization
-do not inactivate
resting - after membrane repolarized
steps in AP
depolarization
- rising phase
- falling phase
- undershoot
- resting
temporal summation
multiple signal over time may reinforce eachother
spatial summation
multiples signals that are physically close may influence eachother
time constant
how long to reach final voltage
- depends on number of channels
- many open channels, lower time constant
length constant
distance required for current to decline
neuromuscular junction
unmyelinated at axon
- release of acetylcholine
- muscle fiber - ligand gated ion channels