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ANP 1106 > Potentials > Flashcards

Potentials Flashcards

1
Q

Do all neurons and all cells have a resting membrane potential?

a) yes
b) only neurons
c) only other cells
d) neither

A

yes

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2
Q

True or False: Neurons can rapidly change their resting membrane potential in a positive direction.

A

True

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3
Q

Neurons are highly excitable like ________ cells

A

Voluntary Muscle

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4
Q

What is required to keep opposite charges separated across a membrane?

A

Energy

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5
Q

What happens when energy is liberated?

A

Charges move towards one another

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6
Q

Do opposite charges attract?

A

Yes

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7
Q

When does the system have potential energy?

A

When opposite charges are seperated

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8
Q

What does it mean when a membrane is polarized?

A

Negative on the inside and positive on the outside

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9
Q

What is voltage?

A

A measure of potential energy generate by separated charge

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10
Q

How is voltage measured?

A

Between two points in volts (V) or millivolts (mV)

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11
Q

Define potential difference or potential

A

The charge difference across the plasma membrane

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12
Q

What results in a higher voltage?

A

Greater charge difference between points

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13
Q

What is current?

A

The flow of electrical charge (ions) between two points

Can be used to do work

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14
Q

What is the flow of current dependent on?

A

Voltage and resistance

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15
Q

What is resistance?

A

It hinders current

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16
Q

What is a substance with high electrical resistance called?

A

Insulator

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17
Q

What is a substance with low electrical resistance called?

A

Conductor

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18
Q

What are the two main types of ion channels?

A

Leakage (nongated)
Gated

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19
Q

Which types of channels are always open?

A

Leakage (nongated)

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20
Q

How do gated channels work?

A

Part of the protein changes shape to open/close the channel

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21
Q

What are the three main gated channels?

A

Chemically gated
Voltage-gated
mechanically gated

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22
Q

What is the role of membrane ion channels?

A

Large proteins (channels) that selectively let ions through the membrane

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23
Q

What passes through k+ ion channels?

A

k+ ion

24
Q

Which channel will only open with the binding of a specific chemical? Name one chemical that might bind to it.

A

Chemically gated (ligand-gated)

Neurotransmitter

25
Q

Which channels open and close in response to changes in membrane potential?

A

Voltage-gated ion channels

26
Q

Which channels open and close in response to physical deformation of receptors such as sensory receptors?

A

Mechanically gated channels

27
Q

What is the electrochemical gradient

A

The combination of the electrical and chemical gradient

ion flow create an electrical current + voltage changes across membrane

28
Q

What factors are important to cell voltage?

A

the difference in ion concentration inside and outside the cell + conductance (permeability) for that ion across the membrane

One cannot work without the other

29
Q

What causes the resting membrane potential to change?

A

Change in [] of ions across membrane
Change in membrane permeability to ions

30
Q

What types of signals do changes in membrane potential cause?

A

Graded potentials- Incoming signals over short distances
Action potentials- Long distance signals of axons

31
Q

What is the purpose of changes in the membrane potential?

A

Used to create signals to receive, integrate, and send information

32
Q

What is depolarization?

A

decrease in membrane potential (moves toward zero and above)
Inside of the membrane less negative then the resting membrane potential

33
Q

Does depolarization decrease the probability of impulses occurring?

A

No- It increases the probability of producing impulses

34
Q

What is hyperpolarization?

A

Increase in membrane potential (away from 0)
Increase of membrane becomes more negative than resting membrane potential

35
Q

Does hyperpolarization increase or decrease the probability of producing impulses

A

decrease

36
Q

Describe Graded potentials in detail

A

Short-lived changes in membrane potential that are triggered by a stimulus that opens gated ion channels

37
Q

What are graded potentials names according to?

A

Location and function

38
Q

What are the types of graded potentials? What are there differences?

A

Receptor/generator potential- graded potentials in receptors of sensory neurons
Postsynaptic potential- Neurons graded potential at a synapse

39
Q

True or false: In graded potentials, a stronger stimulus results in more voltage changes and farther current flows?

A

True

40
Q

True or false: In graded potentials, the current flows for a long time without decaying?

A

False- The current flows but dissipates quickly and decays because the current is lost through “leaky” plasma membrane and voltage is decremental

41
Q

What is the principal way that neurons send signals?

A

Action Potentials

42
Q

Where do action potentials occur?

A

Muscle cells and axons of neurons

43
Q

True or false: Action potentials decay over long distances?

A

False- Action potentials do not decay over long distances because it is constantly being regenerated

graded potentials do

44
Q

What is another term for an action potential?

A

Nerve impulse

45
Q

How are action potentials generated?

A

Na+ influx causes depolarizations down the length of the axon

46
Q

Why does the action potential move in one direction down the axon?

A

Absolute refractory period

47
Q

What is the difference between the relative and absolute refractory period?

A

The relative refractory period can be overcome by a strong enough stimulus while the absolute refractory will not respond to any stimulus no matter how strong

48
Q

What is a refractory period? How does it occur?

A

The time in which a neuron cannot trigger another AP

This occurs because the voltage-gated Na+ channels are open so the neuron cannot respond to another stimulus

49
Q

Which refractory period enforces one-way transmission of nerve impulses and ensures that each action potential is an all-or-none event?

A

Absolute

50
Q

What is happening during the absolute refractory period on a biological basis?

A

The time from the opening of Na+ channels until resetting of the channels

51
Q

What comes first, the absolute or relative refractory period?

A

Absolute, then refractory

52
Q

What is happening on a biological basis during the relative refractory period?

A

Most Na+ channels have returned to their resting state
Some K+ channels are still open
Repolarization is occurring

53
Q

How does the CNS tell the difference between a weak stimulus and a strong one?

A

Frequency of impulses- Aps received per second
Higher frequency means stronger stimulus

54
Q

True or false: The intensity of the stimulus increases the strength of the action potential?

A

False- Only the frequency of APs has an effect on the strength of the action potential

55
Q

What are the subdivisions of postsynaptic potentials?

A

Excitatory (EPSP)
Inhibitory (IPSP)

56
Q

What are the differences between excitatory postsynaptic potentials and inhibitory postsynaptic potentials?

A

EPSP-
Trying to generate an AP by depolarizing the membrane and moving the membrane potential toward the threshold

Opens channels that allow simultaneous fluxes in Na+ and K+

Moves toward 0 mV

IPSP-
Trying to move the membrane away from the threshold by hyperpolarizing

Opens K+ or Cl- channels

Moves toward - 90 mV

57
Q

What are the similarities between EPSPs and IPSPs?

A

Their gates are both opened by chemicals ex. neurotransmitters

The refractory period is absent

The summations are present; temporal or spatial

Conduction distance is the same

Voltage independent; Occurs when NT is no longer present

ANP 1106 (9 decks)

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