physiology neurophys Flashcards
electrical potential inside a neuron is
70 millivolts more negative than the potential in the extracellular fluid on the outside of the fiber
resting membran potential of a neuron is produces by the total
ion concentration differences across the membrane
what is the reversal of potential referring to
the charges switch on the outside from negative to positive and in the inside from positive to negative
at the end of the AP what happens to the charges?
it restores itself
propagates refers to
how the AP moves along the neuron like a wave
if a charge is below the threshold stimulus what will happen?
an AP is NOT generated due to it being an “all or nothing response”
at rest is there more Na+ outside or inside of the cell at rest?
outside
there is high amounts of Na+ inside of the cell?
T/F
F
at rest inside of the membrane it is
negative
at rest there is highest amounts of this ion inside of the cell?
K+
at rest outside of the membrane is
positive
at rest the membrane is _______ to Na+
impermeable
nerve cells and muscle cells are capable of doing this because they are known as “excitable”
self-generating electrical impulses across their membrane
formation of membrane potential involves these 4 things
- selective permeability
- concentration differences of ions
- electrical potential
- separation of charge
resting membrane potential is established due to the difference
of EXCITABLE cells across the membrane at rest
how is a membrane potential created
a concentration difference of ions across a semi-permeable membrane
nernst equation is converts what to what?
concentration difference for an ion into a voltage
what is expressed at a intracellular potential relative to extracellular potential
membrane potential
resting membrane potential is established by
- diffusion potentials
- membrane permeability
- electrogenic nature of the Na+K+ pump
potassium ion will diffuse in what direction pertaining to a cell
outward
the loss of K+ inside of the cell results in what?
a negative charge inside of the cell
what is the driving force of diffusion
the equilibrium potential
what is the mv of the potential difference needed to stop further net diffusion of k+ out of a neuron?
-90
diffusion of Na+ into the cell will create a
positive charge inside of the cell
the potential difference in mv to stop further net diffusion of Na+ is
65+
neural membranes are more permeable to this ion?
K+
which of the pumps contribute most to the RMP?
potassium leak channels
which pump is responsible for maintaining the Na+ & K+ concentraion difference across the cell membrane
Na+K+ ATPase pump
what pump helps establish a Negative electrical potential inside cells?
Na+K+ATPase pump
E (equilibrium = wants to get here) of Na+ =
+65
E K+ =
-90
E ca2+ =
+120
depolarization
more positive and less negative membrane potential
repolarization/hyperpolarization
making the membrane potential more negative/ less positive
major ion contributing to depolarization
Na+
the major ion contributing to repolarization?
K+
gates of gated ion potentials are referred to as
protein/widgets that regulate the channels
when a channel is open the ions it is selective to pass by ______ diffusion
passive (no atp)
the ion pass through the gates down a (n)
electrochemical gradient
which voltage gated channels are responsible for the upstroke phase/depolarization?
voltage gated Na+ channels
threshold in mv for excitable membrane?
+ 55
why can we not get another AP when in the absolute refractory period
because ALL the Na+ gates are open
