Neural Conduction Flashcards
membrane potential
the difference of electrical charge between the inside and the outside of a cell.
Resting membrane potential
- 70mV
* it’s 70mV less charged on the inside of the cell than the outside of the cell*
random motion
ions move around randomly but are more likely to move down their concentration gradients (from high to low concentration)
electrostatic pressure
opposites attract, like charges move away from each other
sodium-potassium pumps
energy consuming mechanisms in the cell
-continually exchange 3 Na+ ions for 2 K+ ions
depolarization
decreasing a resting membrane potential
(it becomes less negatively charged)
ex: -70mv => -55mv
hyperpolarization
increasing a resting membrane potential
(it becomes more negatively charged)
ex: 30mv => -75mv
after an AP- the K+ channels let in too much
excitatory postsynaptic potentials (EPSPs)
depolarizations of a neuron
increase the likely hood that a neuron will fire (closer to threshold)
inhibitory postsynaptic potentials (IPSPs)
polarizations of a neuron
*decreases the likely hood that neuron will fire (further away from threshold)
graded responses
amplitudes of EPSPs and IPSPs are proportional to stimulation
they can also combine to be bigger
decremental
EPSPs and IPSPs decrease in amplitude as they travel through a neuron
threshold of exitation
the level of polarization necessary to generate an Action Potential. *usually -60mV (10 less than the resting potential)
action potential
a massive (1 millisecond) reversal of membrane potential (from -70mV to about +20mV)
all-or-none response
APs occur to their full extent or not at all
they are not grade, they are all one amplitude and last for the same amount of time
integration
combining a number of signals to create one overall signal
spatial summation
when EPSPs and IPSPs occur at the same time, they combine to create one dip/rise/cancellation in the level of membrane potential
temporal summation
when EPSPs and IPSPs occur in rapid succession, they can combine to create a greater signal
voltage activated ion channels
located along the axons at the nodes of ranvier, these are protein channels that are activated to open at certain levels of membrane potential
usually during an AP
absolute refractory period
a brief period (1-2 milliseconds after AP initiation) where another AP cannot occur
relative refractory period
the period after an AP (2-4 milliseconds) when it is possible for the neuron to fire again, but only by applying higher than normal levels of stimulation
orthodromic conduction
signals sent from the soma to the axon
antidromic conduction
signals sent from the axon to the soma
- doesn’t happen naturally
- we can make it happen w/ drugs
saltatory conduction
in myelinated axons, the signal can go faster bc the APs can jump farther distances
goes from node of ranvier to node of ranvier
