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BECOM Exam 1 > Membrane Potential > Flashcards

Membrane Potential Flashcards

1
Q

what manipulation hyperpolariizes an excitable cell from rest?

A

opening K+ channels

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2
Q

For every turn of the Na/Kase, the cell becomes ____

A

-1 more negative inside the cell

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3
Q

The extracellular concentration of what ion has the greatest influence on the resting membrane potential of excitable cells?

A

K+

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4
Q

What are the 3 primary factors that determine ion conductance across the plasma membrane?

A
  • chemical gradient
  • electrical gradient
  • permeability
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5
Q

Na+ chemical gradient direction

A

inside cell

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6
Q

Na+ electrical gradient direction

A

inside cell

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7
Q

K+ chemical gradient direction

A

outside cell

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8
Q

K+ electrical gradient direction

A

inside cell

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9
Q

If the conductance of an ion is held constant, an increase in driving force would lead to _____

A

an increase in current

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10
Q

Inhibition of Na/K ATPase produces ____

A

depolarization of the membrane potential

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11
Q

What are 2 examples of excitable cells?

A
  • muscle (all 3 kinds)

- neurons

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12
Q

the difference of the charge in the electrical gradient between the extracellular and intracellular fluid

A

membrane potential

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13
Q

what creates an electrical difference and thus an electrical gradient?

A

separation of charges

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14
Q

separation of charges takes energy, true/false?

A

true

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15
Q

how many Na are pumped out of the cell?

A

3

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16
Q

how many K are pumped into the cell?

A

2

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17
Q

what is an electrogenic effect?

A

when there is a -1 charge in the cell because 3 Na moved out and only 2 K moved in

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18
Q

which has a larger footprint, K or Na?

A

K

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19
Q

how do channels maintain selectivity?

A

the selectivity filter must fit perfectly with the ion in order to strip off the water molecules that surround the ion

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20
Q

what part of the single subunit manages selectivity?

A

selectivity filter on the p-segment

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21
Q

what is the attachment of H20 to an ion known as?

A

water of hydration (the lowest energy state)

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22
Q

how does the oxygen align with the Na and K?

A

oxygen has a partial neg charge

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23
Q

where do the waters of hydration re-attach to the K?

A

once K+ is through the cell and in the intracellular compartment

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24
Q

what is the relative charge scale?

A

Extracellular is always set at 0

Intracellular is the difference in electrical charge inside the cell with respect to the outside of the cell

ex: 1 K+ moves out&raquo_space; -1 inside and +1 outside» -2 difference

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25
Q

what does the voltmeter measure?

A

Vm (Membrane Potential Difference)

difference in electrical charge inside cell and in surrounding solution

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26
Q

how many ions does it take to create a membrane potential?

A

only a few (makes huge impact on electrical gradient)

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27
Q

when K+ is equally opposed between the electrical and chemical gradient this is know as _____ _____?

A

equilibrium potential

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28
Q

K+ electrical gradient direction

A

inside cell

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29
Q

K+ chemical gradient direction

A

outside cell

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30
Q

Na+ electrical gradient direction

A

inside cell

31
Q

Na+ chemical gradient direction

A

inside cell

32
Q

Ca++ chemical gradient direction

A

inside cell

33
Q

Ca++ electrical gradient direction

A

inside cell

34
Q

Cl- electrical gradient direction

A

outside cell

35
Q

Cl- chemical gradient direction

A

inside cell

36
Q

_____ creates the membrane potential.

_____ maintains the membrane potential.

A

K+ creates the membrane potential.

Na+ maintains the membrane potential.

37
Q

The RMP is closest to the equilibrium potential for the ion with the ______ permeability

A

highest

38
Q

what keeps the cell from getting to equilibrium potential?

A

Na/K ATPase

39
Q

ion current

A

conductance of ion X driving force

40
Q

conductance vs. resistance

A

inversely proportional

41
Q

conductance vs. permeability

A

directly proportional

42
Q

what is the driving force?

A

difference in membrane potential and equilibrium poteintial for an ion

43
Q

depolarization vs. Vm

A

depolarization decreases Vm

44
Q

hyperpolarization vs. Vm

A

hyperpolarization increases Vm

45
Q

repolarization vs. Vm

A

repolarization returns to Vm

46
Q

when does depolarization occur?

A

opening Na

closing K

47
Q

when does hyperpolarization occur?

A

opening K

opening Cl

48
Q

what does depolarization do to the driving force of Na?

A

decreases the driving force of Na

49
Q

what does depolarization do to the driving force of K?

A

increases the driving force of K (Na/K pump still open)

50
Q

what does hyperpolarization do to the driving force of Na?

A

increases the driving force of Na

51
Q

what does hyperpolarization do to the driving force of K?

A

decreases the driving force of K

52
Q

increasing permeability of K+ will do what to Vm?

A

increase Vm&raquo_space; Hyperpolarization

53
Q

increasing permeability of Na+ will do what to Vm?

A

decrease Vm&raquo_space; Depolarization

54
Q

increasing extracellular K+ will do what to Vm?

A
  • decrease K+ chemical gradient (doesn’t want to leave)
  • K+ stays inside cell
  • decrease Vm&raquo_space; Depolarization (less negative in cell)

Na/K pump still works

55
Q

decreasing extracellular K+ will do what to Vm?

A
  • increase K+ driving force (wants to leave)
  • K+ leaves (inside gets more negative)
  • increases Vm&raquo_space; Hyperpolarization
56
Q

what K+ condition will increase excitability?

A

closing K+ channels, hyperkalemia

57
Q

what K+ condition will decrease excitability?

A

opening K+ channels, hypokalemia

58
Q

what K+ condition will cause an AP?

A

hyperkalemia

59
Q

what K+ condition will NOT cause an AP?

A

hypokalemia

60
Q

what will fasting (low glucose) do to the K+?

A
  • No ATP
  • K+ leak channel is open, K+ leaks out
  • No Ca+ enters cell
  • No insulin released
61
Q

what will eating (high glucose) do to the K+?

A
  • ATP
  • K+ leak channel is closed, K+ does not leak out
  • More K+ enters cell from pump (membrane becomes +)
  • Cell depolarized
  • Ca+ enters cell
  • Insulin released
62
Q

decreasing blood flow does what to Vm?

A
  • Less oxygen available
  • Less ATP available
  • Less pump function
  • Less Na out & Less K in
  • Less driving force for Na
  • Decreases Vm
  • Depolarization
63
Q

3 things channel gates respond to

A
  • changes in MP
  • receptor
  • mechanical forces (hearing, touch, BP)
64
Q

what is the process of channel gating?

A
  • VG channel opens
  • Permeability changes
  • Ion current flow
  • Voltage changes
  • Channel gates change
65
Q

In the presence of _____ a voltage change occurs causing an outward K+ current

A

TTX - Na+ channel blocker

66
Q

In the presence of ____ a voltage change occurs causing an inward Na+ current

A

TEA - K+ channel blocker

67
Q

which Na+ gate is fast

A

activation

68
Q

refractory state

A

inactivation gate must re-open

activation gate must close

69
Q

what happens to the membrane potential with cardiac stenosis?

A

Don’t have optimal number of Na+ channels activated, takes longer to depolarize&raquo_space; Causes arrhythmia

70
Q

What is directly linked to refractoriness?

A

Na+ channel gating

71
Q

Administration of GABA binds to a ligand-gates Cl- channel causing these channels to open has what effect on the membrane potential?

A

hyperpolarization of membrane

72
Q

what Cl- condition will decrease excitability?

A

opening Cl- channels

73
Q

What would increasing ECa++ to 140 do to Ca++ driving force and current if:
RMP -60mV
Nernst +130 mV

A

increase driving force

increase current

BECOM Exam 1 (13 decks)

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