Fine, Ch. 2 Flashcards by Carolyne Mackellar

resting membrane potential

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receptor potential

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pacinian corpuscles

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synaptic potentials

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hyperpolarization

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passive electrical responses

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depolarization

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Threshold potential

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action potential

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active transporters

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ion channels

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electrochemical equilibrium

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Best way to observe electrical signals in neurons is by

using an intracellular electrode

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resting membrane potential is the

negative signal reads upon entering neuron

RMP typically -40 to -90 mV

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typical resting membrane potential

-40 to -90 mV

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change in resting membrane potential is a

receptor potential

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receptor potentials are due to

activation of sensory neurons by external stimuli

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XY are for communication between neurons at synaptic contacts

synaptic potentials

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potentials that travel along the nerve axon

action potentials

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action potentials are used for

LONG RANGE transmission of information

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If the potential goes more negative it has

hyperpolarized

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hyperpolarizations are xxx responses

passive electrical responses

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membrane potential becomes more positive

depolarization

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xxx must be met for Action Potential to occur

threshold potential

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intensity of a stimulus is encoded by

frequency of APs

receptor potentials amplitude are graded by

magnitude of the stimulus

action potentials amplitude are graded by

they are not graded; the amplitude is of the same level independent of strength of stimulus, provided the threshold is met.

Synaptic potentials amplitude is graded by

number of synapses activated & previous synaptic activity

fundamental problem with neurons

axons are not good conductors

if current pulse is below threshold it will

decay as it moves away from the site of current injection as it leaks from axonal membrane

serve as a booster system to send info over long distances

action potentials at nodes of ranvier

xxx circumvent the leakiness of neurons

action potentials

neuronal signals rely upon

movement of ions across the membrane

cell membranes transmit electrical signals because they (2)

a. are selectively permeable B. differences in ion concentration across the membrane

ion concentration gradients are established by

active transporters (proteins)

selective permeability of membranes is due to

ion channels

ion channels and transporters work...

against each other to generate the various potentials

an electrical potential will be generated when K+

K+ is not the same on the two sides

difference in electrical potential across the membrane results from

potassium ions flow down their concentration gradient

resting membrane potential is maintained by

continual resting efflux of K+

electrochemical equilibrium is

an exact balance between a) concentration gradient of K+ from in > out, b) an opposing electrical gradient that prevents K+ moving across membrane

K+ stops flowing at

electrochemical equilibrium

tiny fluxes in ions do not disrupt chemical electroneutrality because

each ion has a counter-ion of opposite charge

in opposite compartments, Cl:Na is

equal

passive membrane decrement of current flow with distance formula

Vx = Vo e^-x / /\

voltage response at position x

voltage change at point where current is injected

base of natural logarithms

length constant of the axon

length constant of the axon (/\)

where initial voltage Vo decays to 1/e (37%) of its value

/\ length constant formula

(sqrt) (rm / ro + ri)

relative resistance of plasma membrane

relative resistance of intracellular axoplasm

relative resistance of extracellular axoplasm

for optimal passive flow, rm should be x and ri and ro should be x

high; low; low

delays in change in membrane potential upon injection is due to

plasma membrane behaving as a capacitor, storing initial charge.

change in membrane potential at any time formula =

t = V(infinity)(1-e^-t/T)

V(infinity)

steady state value of membrane potential change

small t =

time after current pulse begins

big T

membrane time constant = time when Vt rises to 1-(1/e) or 63% of V(inf).

membrane time constant

time when Vt rises to 1-(1/e) or 63% of V(inf).

formula to calculate Potential decline after current pulse ends

Vt = V(inf) e^-t/T

Equilibrium potential -

potential generated across the membrane at electrochemical equilibrium

nernst equation predicts what

equilibrium potential

nernst equation formula

Ex = (RT/zF) In(Xout)/(Xin)

simplified nernst at room temp

Ex = 58/z log (Xout)/(Xin)

equilibrium potential

GAS CONSTANT

absolute temp

valence (charge) permeant ion

faraday constant (amount of electrical charge contained in one mole of univalent ion)

faraday constant

amount of electrical charge contained in one mole of univalent ion)

what does the nernst equation predict exactly

linear slope of 58 mV per tenfold change in the K+ gradient

K+ conc. higher inside =

negative inside