what is membrane potential
differences in electircial charge inside/oustide a cell
what is the resting potential
steady membrane potential at -70 mv when neuron is polarized
more Na+ ions outsider cell and k+ ions inside cells
what is the sodium potattsump pump
exchanges 3 Na+ ions for every 2 K+ ions as ions across cell membrane
what do neurotransmitters do
fired form neurons; diffuse across synaptic cleft and interact with receptor molecules on other neurons to either depolraize/hypoerolarize resting potentials
deplorization
decreasing the resting potential; to increase firing (exictation)
hyperpolarization
increasing the resting potential= to decrease firing (inhibition)
what is an action pottential
1 ms; reversal of membran epotneital from -70 mv to + 50 mv for an electrical signal to occur to an ALL or NOTHING response
happens due to changes of voltage-activated ion channels that open/close in response to changing levels of membrane potential
what is the absolute refrtaory period
1-2 ms post-action potential when no AP can be generated
what is the relative refratory period
only possible to fire neurons with an ELEVATED stimulation
describe how an action potential is propogated
- neuron at rest= -70 mv
- intiation of AP (positive charged Na+ charge ENTER= neuron depolarizes)= reaches + 50 mv
- movement of AP (repolarization of axon to negative charge due to negative ions= k+ ions flood OUT)
- hyperpolarization (suuuper negative to -90 mv)
- refratory period (sodium potattisup pump; 3 NA out for 2 K in)
- back to resting state
three stages of an action potential
depoloarization
repolarizaiton
hyperpolarization and refratory period
what is PSPs
post-synpatic potential: changes in the membrane potential of the postsynaptic terminal of a chemical synapse.
what is spatial summation
how multiple signals are integraed into one response (from ESPS + ISPS)
E1 + E2 signals
what is the threshold of exictation
when the sum of depolraization + hyperpolarization is enoughh to depolarize the membrane (around -64 mv)
what is saltatory conduction
‘jumping cnoduction’ whereby an AP travel sdown the nodes of ranvier in myenliated axons to speed up AP
what is ESPS
exictatory posynaptic potentials; exicte the threshold of a neuron to openin the voltage-gated Na+ channels to reverse the neuronal potential= DEPLARIZE
what is IPSPs
inhibitory postsynaptic potentials = HYPOERPOLARIZE
temporal summation
two of the same E1 (e1 + e1)
subthreshold
no summation occurs
spatial summation
Inhibitory and Exictatory (E1 + I1)
process of sodium pottassium pump
- transports 3 Na+ ions out for every 2k+ ions in during resting potential
- ions move down a concentration gradient (Na+ ions tend to enter/k+ to leave)
- negative internal charge= pressures both Na+ and K+ to enter
- sodium pottassium pump transports 3 Na+ out for every 2+ in
what do voltage activated ion channels do
two types: K+ and Na+ channels
they oped/close when changes in membrane potential occur
what happens when the ESPS exictes the threshold
- na+ voltage gated channels open and reverse MP from -70 mv to 50 mv
- na+ channels close which open the k+ voltaged gated channels
- voltage gated k+ ions channels stay open untill resting potential levels out
how does AP conucdtion differ from ESPS/ISPS
- axonal conduction is continous (does’t grow weaker along axonal membrane); nondecremental
- axonal potentials are conducted more slowly than PSPs
- axonal conduction using AP is active whereas IPSP/EPSP is passive
- axonal condition using AP jumps along neurons (saltatory conduction)
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