12.4 – Electrophysiology of Neurons Flashcards
action potential properties
self-propagating
nondecremental (signal maintains amplitude)
all or none
put a single action potential event in order:
local potential depolarizes membrane
threshold is reached
depolarization spike
repolarization
hyperpolarization
which best describes signal conduction in unmyelinated axons?
a wave of depolarization opens more voltage-gated channels immediately distal to the action potential
2 characteristics of local potentials
decremental – signal grows weaker w/ distance
graded – proportional to stimulus strength
T or F:
action potentials only occur where there are voltage-gated ion channels
T
action potentials are only produced by voltage-gated ion channels in the plasma membrane
which term refers to the upward change in membrane potential during an action potential?
depolarization
what is true about signal conduction in myelinated axons?
action potentials are only generated at the nodes of Ranvier
the signal moves more rapidly through the internodes than it does through the nodes of Ranvier
what is true about signal conduction along unmyelinated fibers?
unmyelinated fibers have voltage-gated channels along their entire length
a zone of depolarization excites voltage-gated channels immediately distal to the action potential
what is true about signal conduction along myelinated fibers?
ions can be exchanged with the ECF only at the nodes of Ranvier
there are few voltage-gated ion channels at the myelin-covered internodes and multiple channels at the nodes of Ranvier
action potentials occur only at the nodes of Ranvier
which term refers to decremental changes in electrical potential along a dendrite or the soma?
local potentials
what are properties of action potentials?
all or none
self-propagating
non decremental (signal maintains amplitude)
T or F:
signal conduction is faster in unmyelinated axons because myelin increases the capacitance of the membrane
F
signal conduction is faster in myelinated axons because myelin decreases membrane capacitance
which best describes signal conduction in unmyelinated axons?
a wave of depolarization opens more voltage-gated channels immediately distal to the action potential
T or F:
action potentials occur only when there are voltage-gated ion channels
T
if an excitatory local potential arrives at the trigger zone where the voltage-gated channels are more abundant, it can generate an action potential
what is true about signal conduction in myelinated axons?
the signal moves more rapidly through the ___ than it does through the ___
internodes
nodes of Ranvier
