The Resting Membrane Potential Flashcards

1
Q

Define membrane potential

A

magnitude of electrical charge inside the cell relative to the extracellular solution = mV

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2
Q

How can you measure MP?

A

microelectrode penetrates cell membrane, conducting solution, mV taken

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3
Q

Generating MP requires 2 factors, what are they?

A

Asymmetric distribution of ions across PM and selective ion channels

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4
Q

Which ion dominates the membranes permeability the most?

A

K+, due to open K+ channels

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5
Q

Describe the electrical vs the chemical gradient for K+

A

Towards inside: electrical gradient for K+, +ve attracted to –ve anions

Towards outside: chemical (diffusion) gradient for K+, high to low conc

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6
Q

Which equation can be used to calculate the equilibrium potential?

A

Nernst equation

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7
Q

Which ions are higher in conc inside?

A

K+ and A- (all other anions)

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8
Q

What will increasing the permeability for a particular ion do to the equilibrium potential for that ion?

A

Move it closer to the equilibrium potential

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9
Q

What is the Nerst equation at 37C?

A

61/valency x log10 x [K]o/[K]i

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10
Q

What is the resting MP of a nerve?

A

-70mV

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11
Q

What is the resting MP of a cardiac cell?

A

-90mV

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12
Q

What is selective permeability?

A

Different cells have different channels present allowing different amounts of ions in/out: ion channels

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13
Q

What is equilibrium potential?

A

MP at which the ion will be in equilibrium, given the extra/intra concs

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14
Q

If the membrane is selectively permeable to one ion where will MP be?

A

Equilibrium potential (nernst equation)

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15
Q

Which ions are higher in conc outside?

A

Na+, Cl-, Ca2+

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16
Q

How does the resting membrane potential arise?

A

the membrane is selectively permeable to K+ = there will be a -ve charge across the membrane due to K+ movement out of the cell

17
Q

What is the electrochemical gradient?

A

2 part gradient

chemical gradient = diff in solute conc across a membrane

electrical gradient = diff in charge across a membrane

18
Q

What is the phospholipid bilayer permeable and impermeable to?

A

permeable = small uncharged molecules

impermeable = charged molecules

19
Q

What is the resting MP of a skeletal cell?

A

-90mV

20
Q

Why do some cells have lower resting potentials?

A

Lower selectivity for K+