Quiz 2 Part 2 : Neurophysiology Flashcards
electrical activity of a cell
neurophysiology
two ways neurons communicate
electrical and chemical
within a neuron
electrical (neurophysiology)
between neurons
chemical (neurochemical)
outer layer of the neuron that is a lipid bilayer
cell membrane
separates neuron from what it floats in (CSF)
cell membrane
the inside of the cell is more _____ than the outside of the cell
negative
negatively charged ions
anions
positively charged ions
cations
ions are dissolved in …
intracellular fluid
what is the charge caused by
the difference in ions in the intracellular and extracellular space
membrane potential of -60 to -80mV
resting potential
when the cells interior has a negative polarity at rest
resting potential
proteins that span the cell membrane and allow different types of ions to pass
ion channels
channels that are open all the time
leak channels
allow only potassium ions to cross freely, restrict the flow of certain ions
selective permeability
forces that drive ion movement across the membrane
diffusion and electrostatic pressure
diffusion
molecules distribute themselves evenly through a liquid where they are dissolved
concentration gradient
ions move from areas of high concentration to areas of low concentration
social distancing for molecules
electrostatic pressure
causes ions to flow towards oppositely charged areas
- opposites attract
- like charges repel
typical ionic distribution at rest
salty banana
- inside of cell has lots of K+
- outside cell has ions that make up salt Na+ and Cl-
- more Ca2+ outside cell than in
- cover the banana in salt
how does K+ move in relation to diffusion
diffusion pushes it out of the cell
how does K+ move in relation to electrostatic P
pushes it back into the cell
negatively charged proteins (A-)
do not move, stuck inside the membrane always there
how does Cl- move in relation to diffusion
moves into the cell
how does Cl- move in relation to electrostatic P
pushes it outside of the cell
how does Na+ move in relation to diffusion
into the cell
how does Na+ move in relation to electrostatic P
into the cell, opposites attract
what ion contributes most to keeping neuron at resting potential
K+
at rest, why do K+ ions move into the negative interior
electrostatic pressure
when does K+ reach equilibrium?
when the movement out is balanced by the movement into the cell
why do neurons use a sodium potassium pump?
to maintain resting potential
sodium potassium pump
pumps 3 Na+ out of the cell and 2 K+ into the cell
allows ion exchange against concentration gradient
brief but large change in membrane potential that originates at the axon hillock
action potential
Patterns of action potentials carry information to ___
postsynaptic targets
at rest the membrane is __
polarized
decrease in membrane potential
depolarization
these increase membrane potential
repolarization and hyperpolarization
voltage change that spreads passively across membrane, diminishing as it moves away from the point of stimulation
local potentials
produces small local depolarization, pushes cell closer to threshold, makes it more likely an action potential will occur
Excitatory Postsynaptic Potential (EPSP)
produces small hyperpolarization
- pushes neuron farther away from threshold
Inhibitory Postsynaptic Potential (IPSP)
where does the integration between EPSPs and IPSPs
axon hillock
neuron fires at full amplitude or none
all or none phenomenon
increased frequency =
increased stimulus strength
does a louder noise mean there are larger action potentials?
no. it means there are multiple action potentials
resting membrane potential
-60 to -80 mV
what is/what happens at threshold?
threshold = -55 to -40 mV
the voltage gated Na+ channels open
what is/ what happens at the peak of the action potential?
what is this known as?
peak = +40 mV
Na channels close, K channels open
known as repolarization
what is hyperpolarization in mV
below -80mV
absolute refractory period
does not matter what stimulus is received, you can not physically have another action potential
relative refractory period
difficult to have another action potential, need a really big stimulus to move to an even higher threshold since so low.
action potentials are regenerated along the axon at points known as
nodes of ranvier
each adjacent section is____ and a new action potential occurs
depolarized
the axon potential travels inside the axon and jumps from node to node
- travel in one direction
saltatory conduction
speed of propagation of action potentials, varies with the diameter of the axon
- large diameter = faster speed
conduction velocity
what speeds up communication
myelin
neurotoxin that blocks voltage gated Na and K ion channels
Tetrodotoxin (TTX)
Hw does TTX effect action potential?
prevents depolarization of the action potential, no release of neurotransmitters
neurotoxin that is irreversible activator of Na channels, affects nerve and muscle cells, stabilizes open conformation of voltage gated ion channels
too much Na adding in, depolarization step then plateau
Batrachotoxin (BTX)
