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MSK Exam II > Resting Membrane Potential > Flashcards

Resting Membrane Potential Flashcards

1
Q

What factors contribute to RMP

A

Intracellular anions, Na+/K+ pump, equilibrium potentials of permeable ions

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2
Q

What forces act on an ion

A

net force= [ ]chemical+ electrical forces

netforce = membrane potential (Vm) - equilibrium potential (Ex)

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3
Q

How do you find the equilibrium potential of an ion

A

nernst equation

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4
Q

Membrane potential develops due to the concentration and permeability of what ions

A

Ca2+ Na+ K+ and Cl-

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5
Q

what is meant by equilibrium or steady state

A

no net ion flow across membrane

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6
Q

RMP is expressed in relation to intracell or extracell

A

intracellular potential to extracellular

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7
Q

what contributes to the overall negative intracellular charge

A

impermeable molecules that are retained in the cell

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8
Q

movement of Na+/K+ pump

A

3 Na+ out, 2K+ in

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9
Q

what are the direct and indirect contributions the Na/K pump gives to RMP

A

indirect: [ ] gradients promote passive ion diffusion
direct: active electrogenic pump i.e moving 1+ charge out of the cell

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10
Q

What is a diffusion potential

A

potential difference across cell membrane due to [ ] difference of an ion

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11
Q

what are the trends of K, Na, Ca, and Cl relative to concentration extracellulary

A

K tiny extracellular, huge intra
Na huge extra cell, tiny intra
Ca2 more out than in
Cl huge out, tiny in

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12
Q

Relative comparison of 4 key ions [extra]/[intra]

A

K .026 because more inside
Na 12 because more outside
Ca2 10,000 much more out than in. tiny overall
Cl 29 because more outside

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13
Q

how does force relate to concentration in chemical force

A

increase gradient, increase force

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14
Q

describe the magnitude and direction of electrical force

A

magnitude depends on membrane potential

direction depends on ion charge

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15
Q

how do you find the net force if the concentration and electrical forces are in same direction

A

its the sum

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16
Q

how do you find the net force if the concentration and the electrical forces are in opposite direction

A

subtract

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17
Q

how do you find the net force if the concentration and electrical forces are equal but in opposite directions

A

no net force

18
Q

what is the electrochemical equilibrium

A

no net diffusion of ions when chemical and electrical forces acting on ion are equal and opposite

19
Q

What is the goal of each permeable ion on RMP

A

to drive it toward its own equilibrium potential

20
Q

equation for nernst

A

the Eq potential equals= 60mv/ z log10 [Xout]/[Xin}

z= valences of ion

21
Q 
log 10 (10)= ?
log 10  (.1) =?
A 
log10(10) = 1
log10(.1) = -1
22
Q

If membrane potential is given in Vm and the nernst eq was used for equilibrium potential (Ex) then what can be concluded?

A

the difference between Ex and Vm= net force

if Ex=Vm ion is at equilibrium

23
Q

what is the K+ and Na+ Ex in most cells

A

K+ -105mV

Na+ +45mV

24
Q

What is the Ex of Cl

A

most cells -47mV

skeletal is -89mV

25
Q

What is the Ex for Na and K and Ca in muscle cells

A

Na +67 mV
Ca2 +123mV
K -95mV

26
Q

If the Vm is more negative than the ions Ex what direction will ions go

A

Inward current of cations, anions are repelled

27
Q

If Vm is more positive vs ions Ex what direction will it go

A

outward current of cations, inwards for anion

28
Q

general direction of ion flow

A

K+ goes extracellular

Na+, Ca2+, Cl- goes intracellular

29
Q

what determines membrane conductance

A

number of open channels

30
Q

what are the molecular conductors in cells

A

the ion channels because bilayer is a poor conductor of electricity

31
Q

how do you know if conductance is increasing

A

channels are opening

32
Q

What are the major types of ion channels

A

ungated (leak), voltage-gated

33
Q

Desribe the flow of K+ in cell

A

high intracell concentration but cell is negative. Slow leak of K+ out of cell via leak channels

34
Q

If you decrease the ECF fluid of K+ what happens to flow

A

more K+ efflux

35
Q

as K+ conductance increases what happens to K+

A

efflux

36
Q

What is the reversal potential

A

voltage at which current direction is reversed= nernst potential

37
Q

what is the reversal potential of K+

A

-95mV

38
Q

what is a major determinant of RMP

A

K+ equilibrium potential

39
Q

if you increase or decrease the [Na] ECF what happends to RMP

A

little effect because NA+ channels closed at RMP

40
Q

what is the reversal potential of Na

A

+67mV

41
Q

What is the very average range of RMP

A

-50 to -90 mV

MSK Exam II (10 decks)

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