Neurophysio 1 Flashcards
at equilibrium there is _____ ___ ____
no net movement
Na+ wants to flow ____
in
K+ wants to flow ____
out
Cl- wants to flow ___
in
concentration gradient is a little ____ than electrical pull
stronger
____ ____: the membrane potential when there is a balance between electrical and chemical forces
equilibrium potential
assumption of the equilibrium potential: ____ type of ion can diffuse across the membrane at a time
1
each ion has its ____ equilibrium potential based on ____ ____ and ___ ___
ionic concentration
electrical charge
equilibrium potential predicts:
- ___ of ionic flow
- ___ ____
direction
driving force
___ ___: power of the electrical current; stronger the currect, the faster the flow
driving force
equilibrium potential has 2 other names
reversal potential
nernst potential
___ ___: when there is only 1 ion affecting membrane potential; point at which the polarity of the membrane potential switches
reversal potential
most of the cells resting membrane potential is determined by the equilibrium for ____
POTASSIUM
equilibrium potential ranges from ___ to ___
-65 to -95
resting membrane potential is predicted by the ___ ___ ___ equation
goldman hodgkin katz
GHK found that resting membrane potential is related to the concentration of ____ of the 3 ions and the cells ___ to each
each
permeability
equation for driving force= _____ - _____
resting membrane potential MINUS equilibrium potential for the ion
the larger the driving force, the ___ the ionic current will travel once the cell becomes permeable to that ion
faster
___ channels: responsible for resting membrane potential
leaky channels
__ ___ channels: responds to neural transmission; post synaptic side; neuron communicates
ligand gated
___ ____ channels: responsible for the generation of APs
voltage gated
changes in membrane potential affect the properties ___ ___ ion channels causing them to open or close
voltage gated
___: changing the state of these channels allows for ionic flow into and out of the neuron
current
___ ____ ___: the flow into the cell leads to depolarization and further AP regeneration along the neuronal axon, repeating until it reaches the terminal
positive feedback loop
2 mechanisms that allow ionic flow across the channel
ligand gated
voltage gated
___ ___ potential: more positive charge in the cell than before
excitatory postsynaptic potential
EPSP are controlled by the small influx of ___
Na+
____ ___ potential: makes it harder to generate an action potential
inhibitory postsynaptic potential
___ in the membrane prevents EPSPs from sticking around
leakage
if EPSPs are summed to threshold, a spike is ____
generated
reaching the ___ potential leads to a massive depolarization
threshold
a voltage gated Na+ channel contains a ___ charge
positive
when there is a large enough change in membrane charge, the voltage gated Na+ channel will change conformation and ____
open
voltage gated ion channels are located in ___
clusters
when threshold is reached in one area, it causes a ___ ____ and ___ is reached in adjacent areas; this is the ____ property of an AP
local depolarization
threshold
regenerative
APs happen in an ____ or ____ way
all
nothing
voltage gated Na+ channels inactivate quickly via ___ ___ ___ mechanism
ball and chain
when the membrane potential is too depolarized, the voltage gated Na+ channel’s own side chain ___ the open pore
plugs
voltage gated K+ channels work like voltage gated Na+ channels but they are _____
slower
voltage gated K+ only open after the cell has depolarized so much that the membrane potential is close to ___mV
30
when the cell gets to 30mV there is a huge flow of K+ ___ to reestablish membrane potential
out
_____: so much K+ flows out that the cell is at an even lower membrane potential than at rest
afterhyperpolarization
when the cell detect that afterhyperpolarization occurs, _____ ___ begins to work to increase intracellular Na+ concentrations
Na+/K+/ATPase pump
____ ___ period: voltage gated Na+ channels will not open temporarily, regardless of stimulus; another AP cannot be regenerated
absolute refractory
___ ___ period: while voltage gated K+ channels have opened, the driving force of K+ to leave the cell is much stronger than the driving force for Na+ to enter the cell; it is possible to elicit another AP with a strong enough influx of Na+
relative refractory period
____: the degree to which ion channels are open for a given area on the cell membrane
conductance
changing either the number of channels open or the openness of individual channels will change ___ ___
ionic current
conductance is the invers of ____
resistance
Ohm’s Law _=__x___
voltage (V) = current (I) x resistance (R)
resistance affects current across 2 directions
across the membrane
across the cytoplasm
if there is ____ resistance in the membrane that there is in the cytoplasm, the current will tend to flow through the _______ rather than leaking back out
greater
cytoplasm
as diameter of an axon ____, there is more cytoplasm to flow through instead of back through the membrane.
increases
the bigger axons conduct with ___ velocity
higher
the ____ the axon, the more area it has for ions to flow in, the ____ the action potential is regenerated
fatter
faster
myelinated axons conduct action potential much ___ than unmyelinated axons
faster
