How do Neurons Process Information Flashcards
action potentials
brief (transient) but large changes in the membrane potential
inside of the membrane during action potentials
for an instant, the inside of the membrane becomes positively charged
action potentials triggered
in the axon hillock
action potentials conducted
along the axon
ion channels can open/close for many reasons
a ligand/chemical can bind a receptor
temperature-sensitive
voltage-sensitive
ions flow into/out of cell, alters
membrane potential
hyperpolarization
cell becomes MORE negative
hyperpolarization anions
flow into cell
hyperpolarization cations
flow out of cell
depolarization
cell becomes less negative
depolarization anions
flows into cell
depolarization cations
flows out of cell
threshold #1
stimulus causes a small depolarization of the neuron to the threshold voltage (-40 to -55 mV)
failed initiations also happen here
action potential triggered
all-or-none
what creates a failed initiation of an action potential?
not enough information coming into the cell body
not positive enough to go from -40 to -55 mV
not big enough to reach the threshold potential
depolarization #2
when the interior of the cell becomes positive
repolarization #3
when the membrane potential becomes negative
hyperpolarization #4
when the membrane potential undershoots the RMP
refractory period
neuron cannot generate another action potential until it returns to RMP
resting state #5
when the membrane returns to RMP
information encoded by ____, not ___
number of action potentials, not size
if a neuron wants to send a lot of information:
has to send more action potential, not a bigger action potential
RMP
-60 to -70 mV
K+ channels are open
Na+ channels are closed
small depolarizing stimulus
generated by positive charge from cell body
causes membrane potential to become less negative and approach threshold potential (-40 mV)
at threshold voltage-gated Na+ channels
open/activate (because of change in membrane voltage)
Na+ ions rush into the cell
membrane potential becomes positive
after 1 millisecond, the Na+ channels
inactivate
no more Na+ entering cell
absolute refractory period
absolute refractory period
reset before they can open again- are locked until reset
inactivation
channel closed and temporarily unable to open again
as membrane depolarizes, voltage-gated K+ channels
slowly open/activate
“delayed-activating” K+ channels
K+ flows out of cell
membrane hyperpolarizes
relative refractory period
voltage-gated K+ channels close but other K+ channels stay open
Na+ reset
Which number corresponds to when Na+ ions enter the neuron?
threshold
active propagation of action potential
is slow (10 m/s), but does not weaken
takes many small steps down the axon- some chance of failure at every step
passive propagation- myelinated axon
action potential triggered at axon hillock, moves passively through the myelinated segment- quick (150 m/s), but signal weakens as it travels
at Node of Ranvier
action potential regains full charge through active means (Na/K channels)
then moves passively through next myelinated segment
If someone is exposed to a toxin that blocks voltage-gated Na+ channels, their action potentials will ____
a. get smaller
b. not be generated
c. get larger
b. not be generated
