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
What is the Ex for Na and K and Ca in muscle cells
Na +67 mV Ca2 +123mV K -95mV
26
If the Vm is more negative than the ions Ex what direction will ions go
Inward current of cations, anions are repelled
27
If Vm is more positive vs ions Ex what direction will it go
outward current of cations, inwards for anion
28
general direction of ion flow
K+ goes extracellular | Na+, Ca2+, Cl- goes intracellular
29
what determines membrane conductance
number of open channels
30
what are the molecular conductors in cells
the ion channels because bilayer is a poor conductor of electricity
31
how do you know if conductance is increasing
channels are opening
32
What are the major types of ion channels
ungated (leak), voltage-gated
33
Desribe the flow of K+ in cell
high intracell concentration but cell is negative. Slow leak of K+ out of cell via leak channels
34
If you decrease the ECF fluid of K+ what happens to flow
more K+ efflux
35
as K+ conductance increases what happens to K+
efflux
36
What is the reversal potential
voltage at which current direction is reversed= nernst potential
37
what is the reversal potential of K+
-95mV
38
what is a major determinant of RMP
K+ equilibrium potential
39
if you increase or decrease the [Na] ECF what happends to RMP
little effect because NA+ channels closed at RMP
40
what is the reversal potential of Na
+67mV
41
What is the very average range of RMP
-50 to -90 mV