equilibrium potentials lect 4 Flashcards

1
Q

definition of membrane potential (Vm)

A

electric potential energy stored across plasma membrane; voltage difference (V) across the membrane (m)

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2
Q

what does “potential” in membrane potential refer to

A

ability to do work: this is possible because ions are far away from thier equilibrium potential

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3
Q

what is a resting membrane potential

A

electrical potential difference across plasma membrane of cell that is NOT firing an action potential

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4
Q

the seperation of a greater or lesser number of charges would have a larger membrane potential?

A

the magnitude of the potential depends on the number of opposite charges seperated; the greater the # of charges seperated the greater the potential

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5
Q

What is the concentration of Na+ outside of the cell

A

150 mM

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6
Q

what is the concentration of Na+ inside of the cell

A

15 mM

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7
Q

what is the concentration of K+ inside of the cell

A

150 mM

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8
Q

What is the concentration of K+ outside of the cell?

A

5 mM

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9
Q

What is the concentration of Cl- inside vs outside of the cell

A

inside: 10mM
outside: 120mM

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10
Q

ion channels are polypeptide chains that form what type of pores

A

water filled

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11
Q

some ion channels have gates that are open in the absence of stimuli. What are these called?

A

background channels

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12
Q

name the general types of ion channels

A

1) ungated channel 2) ligand-gated channel 3) voltage-gated channel

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13
Q

when are voltage gated channels closed? when do they open?

A

at resting membrane potential, channel is closed. Membrane depolarization causes channel to open

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14
Q

what is the chemical driving force

A

concentration gradient across the membrane

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15
Q

what is the electrical driving force

A

seperation of charges cause an electrical gradient across the membrane

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16
Q

equilibrium potential

A

diffusions potential (electrical force) that exactly balances or opposes the tendency for diffusion down the concentration gradient

17
Q

when is a particular ion in equilibrium?

A

when chemical and electrical driving forces are equal and opposite

18
Q

impearmeable negatively charged ions are found in the extracellular or intracellular environment?

A

intracellular

19
Q

is K+ or Na+ more permeable? Why?

A

K+; the cell has many more channels open for passive K+ traffic than for passive Na+ traffic

20
Q

at resting potential, the membrane is about how many time more permeable to K+ than Na+?

21
Q

what does the nernst equation calculate

A

calculate the equilibrium potential for AN ion at a given concentration difference across the membrane (Assuming membrane is permeable to ion)

22
Q

what is the nernst equation

A

Eion= (60/z) log ({ion}out/{ion}in) z= ionic valance of ion (charge +/-)

23
Q

Log 1000 =
Log 100 =
Log 10 =

24
Q

Log 1 =

25
Log 0.1 = Log 0.01 = Log 0.001 =
-1; -2; -3
26
what would resting Vm be for a cell to a certain compound (eg: KCl) if cell membrane is impermeable for both ions
0mV | * the only ions that contribute to Vm are those the membrane is permeable to
27
all living cells have some resting membrane potential, but what two types of cells have the ability to produce rapid, transient changes in their membrane potential when excited
nerve and muscle cells
28
what is the numerical value for the resting membrane potential
-70 mv
29
what is the value of resting potential for K+ and Na+; which has a greater influence on Resting membrane potential
EK+ = -90 mV; ENa+ = +65 mV therefore K+ has a greater influence on RMP