Lecture 3 - Electrophysiology of the Cell Membrane Flashcards

1
Q

what is a chemical/concentration gradient?

A

the energy provided by the difference in concentration moving from a high concentration to a low concentration across a plasma membrane

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2
Q

what is an electrochemical gradient?

A

the energy associated with moving charged molecules across the membrane when a membrane potential exists (Na+, K+ and CI-)

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3
Q

what is the concentration of Na+ outside the cell?

A

high

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4
Q

what is the concentration of K+ outside the cell?

A

low

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5
Q

what is the concentration of Na+ inside the cell?

A

low

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6
Q

what is the concentration of K+ inside the cell?

A

high

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7
Q

what is the concentration of Cl- outside the cell?

A

high

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8
Q

what is the concentration of CI- inside the cell?

A

low

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9
Q

what is the number for resting membrane potential?

A

-70mV

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10
Q

what does the Z represent in nersts equation?

A

valence charge

e.g Na+ will have valence charge of +1

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11
Q

what is the potential difference across the cell membrane generated by?

A

principally generated by the Na+/K+ATPase

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12
Q

what does the Na+/K+ATPase pump in and out?

A

pumps out 3Na+ for every 2K+ in

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13
Q

what is the relationship between resting membrane potential and equilibrium potential?

A

RMP is largely an outward K+ mediated equilibrium potential modified by a much smaller inward equilibrium potential for Na+ ions

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14
Q

how is resting membrane potential maintained?

A

K+ and Na+ are moved against their concentration gradient by energy from ATP

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15
Q

what is the relationship between resting membrane potential and ATP?

A

ATP sets up the RMP for every cell but this can be changed by the use of other ions or the opening/closing of channels

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16
Q

what is hyperpolarisation?

A

the change in membrane potential to become more negative

17
Q

what is depolarisation?

A

the change in membrane potential to become less negative (more positive)

18
Q

what is repolarisation?

A

the change in membrane potential to return back to resting membrane potential (more negative)

19
Q

what is a local potential?

A

passive change in membrane potential that is caused by the flow of current across the membrane by small local ion fluxes (channel openings) that occurs when synapses are active
-can depolarise and hyperpolarise

20
Q

what is the relationship between local potentials and RMP?

A

local potential can change without changing RMP as the movement of a few ions is localised to only a small area at any given time

21
Q

what is passive/local potential decay?

A

local potentials decay from the point of origin (Vo) along the length constant

22
Q

what is the relationship between local potentials and time summation?

A

local potentials summate in time as temporal summation and spatial summation

23
Q

what is length constant?

A

the distance the voltage decays to 37% of its original size or Vo

24
Q

what is an action potential?

A

actively propagated depolarization that spreads from the point of origin and typically down the axon to the axon terminal to trigger communication with the next neuron in the sequence

25
Q

what does it mean that an AP is an all or nothing response?

A

AP must meet the threshold (usually 10mV depolarised from RMP) to generate an AP, if the threshold is not met then no AP will be propagated

26
Q

is an AP regenerative?

A

yes as it is propagated without decreasing amplitude

27
Q

what is the advantage of low axial resistance?

A

passes the current down the axon more easily

28
Q

what is the disadvantage of a small axon?

A

results in a much quicker voltage decay because of intrinsic/physical factors of the internal resistance