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602 - Exam 1 > Membrane Action Potential > Flashcards

Membrane Action Potential Flashcards

1
Q

___ channels set up the equilibrium or membrane potential

A

Leak channels

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2
Q

Movement of ion’s is always ___ through all channels

A

passive

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3
Q

Ligand gated channels are isolated on

A

Dendrites and cell bodies

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4
Q

Voltage gated channels are isolated on

A

axon

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5
Q

Neuron to neuron synapse can be stimulatory, inhibitory, or both

A

Both

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6
Q

Neuron to muscle fiber synapse can be stimulatory, inhibitory, or both

A

Stimulatory

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7
Q

Types of glial cells

A

PNS and CNS

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8
Q

PNS contains what types of cells?

A

Satellite and schwann cells

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9
Q

CNS contains what types of cells?

A

Oligodendrocytes
Astrocytes
Microglia
Ependymal cells

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10
Q

Ligand-gated channels are small/large and more/less selective

A

Larger
Less

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11
Q

Gap-junction channels are small/large and more/less selective

A

Larger
Less

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12
Q

What’s the electrical channel?

A
  • Part of the gap-junction channel
  • connects cells to each other and allows ions to move in any direction
  • electrically links cells together
  • Leak channels
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13
Q

Voltage-gated channels allow how many ion types through?

A

1

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14
Q

Voltage-gated channels are small/large and more/less selective

A

small
More

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15
Q

NaK ATPase pump moves ions __ concentration gradient

A

against

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16
Q

What can’t pass through the membrane?

A

Proteins (AA and peptides)

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17
Q

Equilibrium potential

A

single ion moving through membrane

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18
Q

Electromotive force

A

When the neg charge on side I starts pulling back on that side b/c the other side is more positive

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19
Q

Nernst equation

A
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20
Q

monovalent cation X+ equation

A
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21
Q

Monovalent anion Y- equation

A
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22
Q

Average neuron is ___ mV charge within a cell

A

-70 mV

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23
Q

Ek = ___ mV

A

-90

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24
Q

ENa = ___ mV

A

+60

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25
Q

ECl = ___ mV

A

-70

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26
Q

ECa = ___ mV

A

+90

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27
Q

Describe membrane potential

A

Na+ and K+ going through/out of cell simultaneously

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28
Q

voltage gated and ligand gated channels do/don’t contribute to resting membrane potential

A

don’t

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29
Q

membrane potential’s changed due to

A

Leak channels

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30
Q

Leak channels are always open/closed/partially open

A

Open

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31
Q

it takes ___ ions to create small negative charge in membrane

A

few ions

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32
Q

Goldman equation for finding resting membrane potential

A
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33
Q

PK, PNa and PCl permeability at rest

A

1, 0.01, and 0.45

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34
Q

__ Na+ go into cell and ___ K+ go out of cell

A

3
2

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35
Q

Graded potential is also called what

A

local potential
electratonic potential

36
Q

as Na+ moves further from where it enters the ligand gated channels, it gets more/less charge as you move further through the postsynaptic neuron

37
Q

time constant equation

A

time constant = rm x capacitance

38
Q

What does time constant measure?

A

a measure of how fast the charge changes when gates open

39
Q

Graded potential is through ___ gated channels

40
Q

action potential is through ___ gated channels

41
Q

If there’s a smaller time constant, there is ___ depolarization with ___ slope

A

Rapid
Steep

42
Q

Presynaptic neurons act

43
Q

Larger time constant has a ___ change in charge

44
Q

Resting membrane potential’s caused by

A

leak channels

45
Q

Threshold of voltage gated channels is due to

A

ligand gated channels opening

46
Q

depolarization = cell becomes more pos/neg

47
Q

repolarization = cell becomes more pos/neg

48
Q

What are the steps for activation and inactivation in voltage gated Na+ channels

A
  1. at rest = activation gate closed and inactivation gate opened
  2. activation = activation gate opens
  3. inactivation = inactivation gate closes
  4. goes back to rest = activation gate closed and inactivation gate open
49
Q

Activation gate shuts due to

A

below threshold

50
Q

Inactivation gate’s not affected/affected by voltage

A

Not affected

51
Q

Inactivation of voltage gated Na+ is due to

A

conformational change in protein

52
Q

Do Na+ or K+ channels open slower

53
Q

Describe absolute refractory period

A
  • Period during AP
  • neuron doesn’t fire another AP
  • Channels fully open or closed
  • area above threshold where you can’t reactive voltage gated Na+ channels
54
Q

Describe relative refractory period

A
  • neuron can fire another AP but requires more stimulus
  • AP is due to voltage gated Na+ channels
  • Few voltage gated Na+ channels are back to the basal state (resting state)
    — Inactivation gate open and activation gate shut
55
Q

What affects amplitude?

A
  • ENa+
  • How long voltage gated channels are open
  • Conductance
56
Q

What does voltage gate allow for?

A
  • Allows us to determine # of ions flowing through voltage gated channels
57
Q

negative vs. positive current

A

negative = positive ions go into cell
positive = positive ions goes out of cell

58
Q

Current equation

A

current = conductance (g) x voltage (V)

59
Q

Voltage equation

A

Voltage = current (I) x resistance (R)

60
Q

Conductance equation

A

conductance (g) = 1 / resistance (R)

61
Q

Driving force equation for inward sodium current

62
Q

Driving force equation for outward potassium current

63
Q

Do cations have outward or inward flow of ions?

64
Q

Do anions have outward or inward flow of ions?

65
Q

What is tetrodotoxin?

A

It blocks voltage gated Na+ channels
- No depolarization

66
Q

What is tetraethylammonium?

A

It blocks voltage gated K+ channels
- No repolarization

67
Q

What is the voltage clamp equation and describe

A
  • Pronase + TEA
  • Uses instrument to make inside of neuron reach threshold and once it reaches threshold, Na+ channels open (activation gate opens) and stays open until you get below threshold
68
Q

PK, PNa, and PCl value when voltage gated Na+ channels are open

A

PK = 1
PNa = 20
PCl = 0.45

69
Q

___ is the decrease in strength over distance. Does this occur in graded or action potential?

A

Decremental

Graded potential

70
Q

An axon is at rest w/ electrode stuck in the middle of an axon, and you stimulate the inside of the axon to threshold, does the AP move in 1 or both directions? Why?

A

Both b/c none of the voltage gated Na+ channels are in refractory
- It can be stimulated anywhere along the axon

71
Q

During the absolute refractory period, does the AP move in 1 or both directions? Why?

A

1 direction (unidirectional)

Only in front of the AP do you have voltage gated channels being stimulated

72
Q

___% decline in voltage when using the length constant

73
Q

What is spacial summation?

A

When you have 2 synapses pumping in Na+ there is a longer length constant that allows Na+ to travel further before it’s diluted and it’s more likely to reach the voltage gated channels and fire an AP
- Na+ more likely to reach voltage gated channels at axon hillock

74
Q

Length constant equation

A

square root (rm/ri)

75
Q

Do you need to have a larger or smaller length constant for Na+ to travel further?

76
Q

Increasing length constant increases membrane resistance. How?

A

Myelin sheath b/c ions can’t leave membrane

77
Q

Decreasing internal resistance ___ axon size

78
Q

speed of action potential equation

A

length constant/time constant

79
Q

bigger axons transport signals faster/slower

80
Q

Describe statutory conductance. Where are the voltage gated channels? How long can myelin sheaths be?

A
  • when you have a myelin sheath axon, the AP jumps from node to node
  • the voltage gated channels are only at the areas of exposed membrane along the axon
  • myelin sheaths can’t be too long b/c you need diffusion event to occur
81
Q

Lidocaine inhibits what

A

voltage gated Na+ channels (temporarily)

82
Q

A defect in Ca2+ channels causes. What happens?

A

malignant hyperthermia
- your body tells you to increase your body temp, which can be damaging if too high

83
Q

Cystic fibrosis is a ___ gated channel mutation

84
Q

A defect in Na+ channels causes

A

Atypical myotonia

85
Q

Myasthenia gravis is due to a ___ gated channel mutation. What happens?

A
  • ligand
  • Ach (which normally binds to ligand to open Na+ channels) doesn’t allow Na+ to enter which blocks the neurotransmitter and prevents the normal neurotransmitter from binding, so muscles don’t contract
86
Q

What are the 2 types of Ach channels?

A
  • Ach channels binds Ach and nicotine
  • Ach channels binds Ach and muscarine

602 - Exam 1 (10 decks)

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