Chapter 3: Neurophysiology Flashcards

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1
Q

Two ways neurons communicate with each other

A

Electrical and chemical communication

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2
Q

Nerve impulse

A

Neurons receive, integrate, and send electrochemical signals

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3
Q

When salts go into solution, they break apart into ____

A

Ions

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4
Q

Is there more or less of potassium inside a cell?

A

More

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5
Q

Is there more or less of potassium outside a cell?

A

Less

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6
Q

Is there more or less of Sodium inside cell?

A

Less

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7
Q

Is there more or less of sodium outside of a cell?

A

More

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8
Q

Inside of cell is more (negative/positive) than outside

A

Negative

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9
Q

Outside of cell is more (negative/positive) than outside

A

Positive

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10
Q

Resting potential of a neuron

A

-70 mv

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11
Q

What does -70 mv resting potential mean?

A

Inside of cell is 70 mv less than outside of cell

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12
Q

Ions mostly move through _____

A

Channels

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13
Q

Protein channels are ______ for one type of ion

A

Specific

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14
Q

Ion channels are normally closed or ____

A

gated

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15
Q

The two forces that act to drive ion movement

A

Concentration gradient and electrical gradient

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16
Q

Concentration gradient

A

Ions in high concentrations move where it is less concentrated

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17
Q

What is the movement of Na+ due to concentration gradient?

A

From outside to inside

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18
Q

What is the movement of K+ due to concentration gradient?

A

Inside to outside

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19
Q

Electrical Gradient

A

Similar charges repel each other and opposites attract

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20
Q

Movement of Na+ because of electrical gradient

A

It is driven inside where it is more negative

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21
Q

Electrochemical gradient

A

Both electrical and concentration gradients

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22
Q

Where do action potentials begin?

A

Axon hillock

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23
Q

From where to where do axons send information?

A

From cell body to axon terminal

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24
Q

Depolarization

A

If you add positive current to inside of cell and polarity moves toward 0; more positive

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25
Q

Hyperpolarization

A

If you add negative current to inside of cell; polarity moves away from resting potential; more negative

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26
Q

Threshold of excitation

A

-55 mV

27
Q

What happens when neuron reaches threshold of excitation?

A

When voltage gated Na+ channels open and enough positive current flow into to trigger an action potential

28
Q

All-or-none

A

Either generate action potential or you don’t (no in-between)

29
Q

At resting potential, the voltage gated Na+ channels are _____

A

Closed

30
Q

What happens to voltage gated Na+ channels when the membrane is depolarized?

A

Conformation changes open the voltage gated channel

31
Q

What happens after voltage gated Na+ channels open?

A

Na+ enters cell through channels and inside becomes more positive or depolarized

32
Q

When cell reaches positive +50 mV, what happens to the Na+ and K+ channels?

A

Na+ channels inactivate or close. K+ channels open

33
Q

When K+ voltage gated channels are opened, what happens to K+ and inside of cell?

A

It exits cell and inside becomes more negative

34
Q

After-hyperpolarization

A

K+ channels slow to close; more K+ leaks out

35
Q

Na+/K+ Pump

What is the exchange and does it require energy?

A
  • Helps to restore balance of Na+ and K+
  • Moves 3 Na+ ions outside and 2 K+ ions outside
  • It requires ATP
36
Q

Absolute refractory period

A
  • Impossible to generate another AP

- When inside of cell is above threshold of excitation

37
Q

Relative refractory period

A
  • Can generate another AP, but harder
  • During the after-hyperpolarization
  • Need much more positive current to bring membrane to threshold (-55mV)
38
Q

The three phases of an action potential

A

Depolarization, Repolarization, Hyperpolarization

39
Q

What phase(s) of the AP constitute the absolute refractory period?

A

Depolarization and repolarization

40
Q

What phase(s) of the AP constitute the absolute refractory period?

A

Hyperpolarization

41
Q

Toxins and what they affect

A

They are noxious or poisonous substances. They have effects on action potential.

42
Q

Tetrodotoxin and saxitoxin

A

Block voltage gated Na+ channels

43
Q

Scorpion venom

A

Keeps voltage-gated Na+ channels open; closes voltage gated K+ channels

44
Q

2 examples of local anesthetics

A

Lidocaine and novocaine

45
Q

Local anesthetics

A

Block voltage gated Na+ channels in a localized area

46
Q

To propagate

A

To generate/give rise to

47
Q

Is action potential re-generated along axon?

A

Yes

48
Q

What is pattern of action potential along a myelinated axon?

A

It appears to skip along the axon

49
Q

Nodes of ranvier

A
  • Spaces between sections of myelin

- High concentrations of ion channels

50
Q

Myelin

A

Good insulator

51
Q

Multiple sclerosis

A
  • Autoimmune disease
  • Lose insulation, ions leak out
  • Propagation affected; muscle slowness, weakness
52
Q

Non-decremental

A
  • regenerate along the axon

- Size and shape same every time

53
Q

Neurons receive

A

Graded potentials

54
Q

Neurons integrate

A

What happens at axon hillock (does the membrane each threshold of excitation?)

55
Q

Neurons send

A

action potential and release of chemicals

56
Q

Graded potentials

A

Small membrane potentials that can be excitatory or inhibitory

57
Q

Grade potentials’ size is proportional to

A

size of stimulus that generates them

58
Q

Are graded potentials persistent over time?

A

No, they decay over time and space. They are non-regenerative

59
Q

EPSP occur due to ____ or ____ influx

A

Na+ or Ca++

60
Q

EPSPs are each ____ for generating action potential

A

sub threshold

61
Q

IPSPs usually result from ___ or ___

A

Cl- influx or K+ efflux

62
Q

How do EPSPs and IPSPs add together?

A

The ions diffuse inside cell and their concentration decays with space and time. They summate at axon hillock.

63
Q

Neuronal decision-maker

A

Axon hillock; decides if enough to reach threshold of excitation and if so, it generates an action potential

64
Q

Neurons that receive signals receive them from other neurons that send them

A

True; concept check