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SF1 1 > Membrane Potential > Flashcards

Membrane Potential Flashcards

1
Q

Is extracellular or intracellular [Na+] higher?

A

Extracellular

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2
Q

Is extracellular or intracellular [K+] higher?

A

Intracellular

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3
Q

Is extracellular or intracellular [Ca+] higher?

A

Extracellular

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4
Q

Is extracellular or intracellular [Mg2+] higher?

A

Extracellular

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5
Q

Is extracellular or intracellular [Cl-] higher?

A

Extracellular

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6
Q

Concentration (mM) x valence = ?

A

mEQ

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7
Q

Why can’t a a cell with only a lipid membrane have a membrane potential?

A

Bulk electroneutrality and ions cannot cross the membrane

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8
Q

What is being balanced when K+ leak channels reach an equilibrium state?

A

Concentration gradient of the higher intracellular potassium and the electric resistance to flow (inside becomes more negative)

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9
Q

Abbreviated Nernst Equation

A

Ek=(61)(mV)log(Ko/Ki)

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10
Q

Equation describing the resting equilibrium state of a membrane with more than one permeable ion

A

Goldman Equation (G-H-K equation)

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11
Q

The external membrane surface typically has a negative or positive charge?

A

negative (despite the extracellular fluid itself being relatively positive)

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12
Q

Do monovalent or divalent cations bind to the negative charges on the extracellular membrane leaflet?

A

Divalent. Monovalent “not charged enough” to bind.

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13
Q

Decreases in extracellular Ca2+ and Mg2+ are called what, respectively?

A

Hypocalcemia and hypomagnesemia

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14
Q

“unscreened” negative charges on the cell membrane outer surface have what affect on the charge difference across the membrane?

A

Reduce the total charge difference. Resting potential less negative

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15
Q

Ease of movement of a substance through the cell membrane

A

Membrane Permeability (Pm)

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16
Q

Determined by the number of open ion channels in the membrane

A

Ion membrane permeability

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17
Q

Ease of movement of electric charge through the cell membrane.

A

Membrane conductance

18
Q

Unit for membrane conductance

A

Siemens (S)

19
Q

Relationship between membrane conductance and resistance

A

Resistance is the inverse of conductance

20
Q

Rate of charge flow across the cell membrane

A

Membrane current (measured in Amperes - A)

21
Q

Total net difference in electrical charge distribution across the cell membrane

A

Membrane potential (measures in Volts - V)

22
Q

How is the driving force for an ion determined?

A

Difference between membrane potential and an ion’s equilibrium potential

ΔVion = (Vm - Eion)

23
Q

(Driving Force) x (Conductance) = ?

A

current

24
Q

Outward current. Makes the cell interior more negative or positive?

A

More negative (efflux of cations or influx of anions)

25
Q

Inward current. Makes the cell interior more negative or positive?

A

More positive (influx of cations or efflux of anions)

26
Q

Positive current is outward or inward?

A

Outward

27
Q

Negative current is outward of inward?

A

Inward

28
Q

Capability (of the membrane) to store electrical charge

A

Membrane Capacitance (measured in Farads - F)

29
Q

Describes the lag between current flow and change in membrane potential. Determined by total membrane resistance (Rm) and total membrane capacitance (Cm)

A

Membrane Time Constant

30
Q

Why does membrane potential change slower than membrane current?

A

Membrane current changes instantaneously if there’s a change in driving force or conductance but it takes time to rearrange the the charges stored on the cell membrane.

31
Q

Two determinants of membrane capacity to store charge

A

Surface area (pos relationship) and thickness (neg relationship)

32
Q

Membrane Time Constant = ?

A

(resistance) x (capacitance)

33
Q

total membrane conductance is the product of… (2)

A

(number of open channels) x (individual channel conductance)

34
Q

Increasing Rm will have what effect on the time constant

A

increases the time constant

35
Q

Increasing Cm will have what effect on the time constant

A

increases the time constant

36
Q

Describes the decay in effect over distance along a cylindrical membrane area. Higher value means more current flow.

A

Length Constant (λ)

37
Q

Determinants of the length constant (2)

A

membrane resistance (Rm) and axial resistance (Ra)

38
Q

Resistance to current flow along cylindrical area of membrane

A

axial resistance

39
Q

Does higher axial resistance increase or decrease the length constant

A

decrease

40
Q

Large diameter axons have a larger or smaller axial resistance?

A

Small Ra

41
Q

Small diameter axons have a larger or smaller axial resistance?

A

Large Ra

SF1 1 (8 decks)

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