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PSYC 211 > Lecture 3: The Action Potential > Flashcards

Lecture 3: The Action Potential Flashcards

1
Q

Golgi stain

A

a mixture of silver nitrate and potassium chromate that causes 2% of brain cells to darken in colour as silver chromate crystallizes inside of them, in every nook and cranny.

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2
Q

The structure of the nervous system was discovered by

A

Camillo Golgi & Santiago Ramón y Cajal. they won the Nobel Prize in 1906 for their work on the structure of the nervous system

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3
Q

Soma/ Cell body

A

Where the nucleus is located

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4
Q

Processes

A

protrusions of the neuron that extend out of the soma

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5
Q

Dendrites

A

branched, treelike extensions from the soma that are responsible for sensing the external environment (for collecting information relevant to the cell).

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6
Q

Axon

A

responsible for transmitting information (via an action potential) to downstream cells

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7
Q

Myelin sheaths

A

insulate the axon to improve the speed and fidelity of the action potential

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8
Q

Axon collaterals

A

the branches of an axon

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9
Q

Axon terminal/ Terminal Bouton

A

responsible for releasing neurotransmitters to downstream cells when there is an action potential

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10
Q

Synapse

A

The junction between an axon terminal and the membrane of a downstream neuron

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11
Q

Electrical Potential

A

The potential for electricity to flow (doesn’t mean there is actual current flowing)

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12
Q

Measuring electric potential

A

measured with glass micropipettes filled with solutions which conduct charge. The micropipette is inserted through the membrane into the cell. The voltmeter measures the difference in electrical charge between two points (the potential difference)

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13
Q

Electrical potential is measured in

A

millivolts (mV)

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14
Q

The resting membrane potential is

A

-40 and -90 mV

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15
Q

Ions

A

charged atom or molecule

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16
Q

Cation

A

positively charged ion

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17
Q

Monovalent Cation examples

A

Na+, K+

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18
Q

Divalent Cations examples

A

Ca 2+, Mg 2+

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19
Q

Anion

A

negatively charged ion

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20
Q

Monovalent anion example

A

Cl-

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21
Q

Electrostatic pressure

A

attractive force between molecules that are oppositely charged (i.e., positive and negative) or repulsive force between molecules that are similar charged (e.g., positive and positive)

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22
Q

Ion channels

A

Specialized protein molecules that sit in the cell membrane. They have a pore (hole) in them through which specific ions can enter or leave cells.

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23
Q

Leak channel

A

An ion channel protein that is in the membrane and has a pore that is always open (e.g., potassium leak channel).

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24
Q

Intracellular fluid

A

fluid contained within cells

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25
Q

extracellular fluid

A

fluid located outside of cells

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26
Q

neurons sit in and are full of ___

A

salt water

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27
Q

the lipid bilayer is ___ to ions

A

impermeable

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28
Q

If there is an equal charge of positively and negatively charged ions on either side of the membrane, then

A

inside of cell = 0 mV

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29
Q

Sodium-Potassium Pump goal

A

pumps sodium ions out of the cell and potassium ions in the cell

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30
Q

Sodium-Potassium Pump steps

A
  1. the sodium-potassium pump binds 3 sodium ions and a molecule of ATP
  2. the splitting of ATP provides energy to change the shape of the channel and drive sodium ions through the channel
  3. the sodium ions are released to the outside of the membrane and the new shape of the channel allows two potassium ions to bind
  4. release of the phosphate allows the channel to revert to its original form, releasing the potassium ions on the inside of the membrane
31
Q

the sodium-potassium pump causes K+ ions to be ___ times more concentration ____ the cell than ____

A

30; inside; outside

32
Q

the sodium-potassium pump causes Na+ ions to be ___ times more concentration ____ the cell than ____

A

15; outside; inside

33
Q

Diffusion

A

Molecules move from areas of high concentration to low concentration

34
Q

Leak Potassium Channels

A

the cell membrane of neurons contains K+ leak channels that are selectively permeable to K+. allows K+ to move out of the cell & along the concentration gradient. sets up the negative resting membrane potential

35
Q

If K+ was the only ion that could cross the membrane, the electrical potential of the membrane would settle at

A

-90mV

36
Q

the more K+ leak channels a neuron has, the closer the membrane potential will be to

A

-90 mV

37
Q

Membrane potential

A

the difference in electrical potential inside and outside the cell

38
Q

Why is the resting potential of most neurons less than -90mV

A

because other ions can sneak through other types of leak channels

39
Q

Resting potential

A

The membrane potential of a neuron when it is not being altered by signalling molecules that cause excitatory or inhibitory postsynaptic potentials

40
Q

Receptors

A

proteins found in the cell membrane that act as sensors

41
Q

T or F: Many receptors on the neuronal membrane are ion channels that allow ions to flow through

A

T

42
Q

Depolarization

A

When the membrane potential of a cell becomes less negative than it normally is at rest

43
Q

T or F: Potassium can always flow through the potassium leak channels in either direction

A

T (but will usually flow out due to the concentration gradient)

44
Q

Sodium Channel

A

Opens in response to a nerve impulse (when the membrane potential reaches -40 mV). the influx of Na+ depolarizes the membrane and opens more Na+ channels, causing the membrane potential to shoot up to +40 mV

45
Q

T or F: The sodium channel is inactivated for a brief period following activation

A

T

46
Q

The Action Potential

A

A brief electrical impulse that provides the basis for the conduction of information along the axon

47
Q

Threshold of excitation

A

value of the membrane potential that must be reached

48
Q

The Action Potential Steps

A
  1. Sodium channels open
  2. Potassium channels open
  3. Depolarization
  4. Sodium channels close
  5. Repolarization
  6. Potassium channels begin to close
49
Q

Potassium Channel

A

Start to open on the upswing of the action potential (when the membrane potential reaches above 0 mV). The outflux of K+ through these channels, driven now by diffusion and electrostatic forces, drives the membrane potential back down within a millisecond

50
Q

Refractory period

A

post action potential hyperpolarization

51
Q

Repolarization

A

When the membrane potential of a cell becomes more negative than it normally is at rest

52
Q

Wire electrode

A

placed in the extracellular fluid; it is an electrical conductor that provides a path for the electricity to enter or leave the medium

53
Q

Fine glass microelectrode

A

inserted into the axon to record the activity of a neuron

54
Q

Oscilloscope

A

a sensitive voltmeter that turns electrical fluctuations into visible signals

55
Q

Calcium Channels

A

When the action potential arrives at the axon terminal, Ca 2+ channels open, causing it to enter the axon terminal. The influx of calcium causes several synaptic vesicles to simultaneously fuse with the presynaptic membrane.

56
Q

Calcium is ___ times ___ concentration outside the cell than in

A

1000; more

57
Q

Synaptic transmission

A

transmission of messages from one neuron to another via the presynaptic release of a neurotransmitter that crosses the synapse and binds to receptors located on the postsynaptic membrane.

58
Q

conduction of the action potential

A

the movement of information along the axon

59
Q

T or F: Conduction of an action potential can happen in either direction

A

false

60
Q

T or F: the size of the action potential remains constant

A

true

61
Q

all-or-none law

A

action potentials occur or don’t occur and once triggered, they will propagate down the axon without growing or diminishing in size to the end of the axon

62
Q

rate law

A

the strength of the stimulus is represented by the rate of the firing axon

63
Q

the sodium-potassium pump requires

A

ATP

64
Q

t or f: potassium leak channels are always open

A

t

65
Q

neuron function

A

orchestrate and control the movement of the multicellular organism

66
Q

ways neurons transmit information

A

electrically and chemically

67
Q

electrical signalling

A

relies on changes in the membrane potential (Vm), the difference in charges inside and outside the cell

68
Q

chemical signalling

A

relies on the release of neurotransmitters at the axon terminals onto other neurons

69
Q

cytosol

A

the salty solution that fills the cell

70
Q

In what direction do potassium leak channels go?

A

both

71
Q

what is the threshold of excitation?

A

-55 mv

72
Q

at the peak of the action potential, the membrane potential is

A

40 mv

73
Q

when do potassium channels open?

A

on the upswing of the action potential (around 0 mv)

74
Q

how would you widen an action potential?

A

by infusing a voltage-gated channel antagonist

PSYC 211 (23 decks)

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