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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
what does the voltmeter measure?
Vm (Membrane Potential Difference) difference in electrical charge inside cell and in surrounding solution
26
how many ions does it take to create a membrane potential?
only a few (makes huge impact on electrical gradient)
27
when K+ is equally opposed between the electrical and chemical gradient this is know as _____ _____?
equilibrium potential
28
K+ electrical gradient direction
inside cell
29
K+ chemical gradient direction
outside cell
30
Na+ electrical gradient direction
inside cell
31
Na+ chemical gradient direction
inside cell
32
Ca++ chemical gradient direction
inside cell
33
Ca++ electrical gradient direction
inside cell
34
Cl- electrical gradient direction
outside cell
35
Cl- chemical gradient direction
inside cell
36
_____ creates the membrane potential. _____ maintains the membrane potential.
K+ creates the membrane potential. Na+ maintains the membrane potential.
37
The RMP is closest to the equilibrium potential for the ion with the ______ permeability
highest
38
what keeps the cell from getting to equilibrium potential?
Na/K ATPase
39
ion current
conductance of ion X driving force
40
conductance vs. resistance
inversely proportional
41
conductance vs. permeability
directly proportional
42
what is the driving force?
difference in membrane potential and equilibrium poteintial for an ion
43
depolarization vs. Vm
depolarization decreases Vm
44
hyperpolarization vs. Vm
hyperpolarization increases Vm
45
repolarization vs. Vm
repolarization returns to Vm
46
when does depolarization occur?
opening Na | closing K
47
when does hyperpolarization occur?
opening K | opening Cl
48
what does depolarization do to the driving force of Na?
decreases the driving force of Na
49
what does depolarization do to the driving force of K?
increases the driving force of K (Na/K pump still open)
50
what does hyperpolarization do to the driving force of Na?
increases the driving force of Na
51
what does hyperpolarization do to the driving force of K?
decreases the driving force of K
52
increasing permeability of K+ will do what to Vm?
increase Vm >> Hyperpolarization
53
increasing permeability of Na+ will do what to Vm?
decrease Vm >> Depolarization
54
increasing extracellular K+ will do what to Vm?
- decrease K+ chemical gradient (doesn't want to leave) - K+ stays inside cell - decrease Vm >> Depolarization (less negative in cell) Na/K pump still works
55
decreasing extracellular K+ will do what to Vm?
- increase K+ driving force (wants to leave) - K+ leaves (inside gets more negative) - increases Vm >> Hyperpolarization
56
what K+ condition will increase excitability?
closing K+ channels, hyperkalemia
57
what K+ condition will decrease excitability?
opening K+ channels, hypokalemia
58
what K+ condition will cause an AP?
hyperkalemia
59
what K+ condition will NOT cause an AP?
hypokalemia
60
what will fasting (low glucose) do to the K+?
- No ATP - K+ leak channel is open, K+ leaks out - No Ca+ enters cell - No insulin released
61
what will eating (high glucose) do to the K+?
- 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
decreasing blood flow does what to Vm?
- Less oxygen available - Less ATP available - Less pump function - Less Na out & Less K in - Less driving force for Na - Decreases Vm - Depolarization
63
3 things channel gates respond to
- changes in MP - receptor - mechanical forces (hearing, touch, BP)
64
what is the process of channel gating?
- VG channel opens - Permeability changes - Ion current flow - Voltage changes - Channel gates change
65
In the presence of _____ a voltage change occurs causing an outward K+ current
TTX - Na+ channel blocker
66
In the presence of ____ a voltage change occurs causing an inward Na+ current
TEA - K+ channel blocker
67
which Na+ gate is fast
activation
68
refractory state
inactivation gate must re-open | activation gate must close
69
what happens to the membrane potential with cardiac stenosis?
Don't have optimal number of Na+ channels activated, takes longer to depolarize >> Causes arrhythmia
70
What is directly linked to refractoriness?
Na+ channel gating
71
Administration of GABA binds to a ligand-gates Cl- channel causing these channels to open has what effect on the membrane potential?
hyperpolarization of membrane
72
what Cl- condition will decrease excitability?
opening Cl- channels
73
What would increasing ECa++ to 140 do to Ca++ driving force and current if: RMP -60mV Nernst +130 mV
increase driving force | increase current

BECOM Exam 1 (13 decks)

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