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Intro to Neuroscience > Neurophysiology > Flashcards

Neurophysiology Flashcards

1
Q

Galvani

A

-electrical current applied to a dissected nerve causes the muscle connected to the nerve to twitch
-concluded that electricity flows along the nerve
-experiment was conducted on frogs

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2
Q

Fritsch and Hitzig

A

-electrical stimulation of the neocortex causes movement of arms and legs
-experiment was done on dogs

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3
Q

Bartholow

A

-First report of human brain stimulation
-1874

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4
Q

Caton

A

-first attempt to measure electrical currents of the brain using a voltmeter and electrodes on the skull
-performed on rabbits and monkeys

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5
Q

von Helmholtz

A

-flow of information in the nervous system is too slow to be a flow of electricity

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6
Q

Bernstein

A

-determined that the charge doesn’t travel along the axon, the wave does

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7
Q

Microelectrodes

A

-electrodes small enough to place on or in an axon
-can be used to measure a neuron’s electrical activity and deliver an electrical current to a single neuron

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8
Q

Oscilloscope

A

-serves as a sensitive voltmeter
-used to record voltage changes on an axon

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9
Q

Squid axon

A

-much larger than human axons
-easier to perform experiments on
-used to investigate the basis of action potentials

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10
Q

Resting membrane potential

A

-a store of negative energy on the intracellular side relative to the extracellular side
-approximately -50 to -80 mV
-found by a microelectrode inserted into a resting cell

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11
Q

Ion channels

A

-found in the lipid bilayer
-allow ions to pass through the membrane
-open in close in response to voltage changes, chemicals, or mechanical action

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12
Q

Passive channnels

A

-always open to a specific ion
-ungated channels allow potassium and chlorine to move in and out of the cell freely

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13
Q

Potassium channels

A

-lined with oxygen that mimic water molecules
-potassium can pass through the filter but sodium cannot

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14
Q

Gated channels

A

-normally closed, ions can’t freely pass
-gated sodium channels keep sodium ions out
-electrical, chemical, and physical

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15
Q

Active transporters

A

-ex: sodium potassium pump
-enzyme that breaks bond in ATP
-each ATP pushes 3 sodium ions out of cell and 2 potassium ions into the cell

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16
Q

Sodium and chloride ions are at a higher concentration ____ the cell

A

outside

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17
Q

Potassium and larger proteins are at a higher concentration _____ the cell

A

inside

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18
Q

Diffusion

A

-movement of ions down the concentration gradient

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19
Q

Voltage gradient

A

-difference in charge between 2 regions that allows a flow of current if the two regions are connected

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20
Q

Electrostatic pressure

A

-causes ions to flow to oppositely charged areas

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21
Q

What two opposing forces drive ion movement?

A
  1. diffusion
  2. electrostatic pressure
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22
Q

At rest, K+ ions move ______ the cell because of electrostatic pressure

A

inside

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23
Q

As K+ ions build up inside the cell, they also _____ out of the membrane along the _______ ________

A

diffuse, concentration gradient

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24
Q

Sodium-Potassium Pump

A

-used to maintain membrane potential
-creates concentration gradient by pumping 3 Na+ outside the cell for every 2 K+ pumped in

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25
Q

T/F the sodium-potassium pump requires ATP

A

yes because the pumping of ions is against the concentration gradient

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26
Q

Why is the extracellular space more positive?

A

-membrane is more permeable to potassium ions

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27
Q

Nernst equation

A

-predicts the voltage needed to counterbalance the diffusion force pushing an ion across a membrane
-predicts the equilibrium potential of an ion, usually K+
-predicts -80mV

28
Q

Goldman equation

A

-predicts voltage potentials closer to observed resting potentials at -65 mV

29
Q

Neural transmission

A

Communication between neurons results from changes in the resting membrane potential

30
Q

Hyperpolarization

A

increase in membrane potential, the interior of the membrane becomes even more negative, relative to the outside

Usually due to the inward flow of chloride ions or outward flow of potassium ions

31
Q

Depolarization

A

decrease in membrane potential, interior of the cell becomes less negative

reaches up to +40 mV

Usually due to the inward flow of sodium

32
Q

Ungated channels allow ___ and ___ to move into and out of the cell more freely, but gated sodium channels keep out ____.

A

k+, Cl-

Na+ ions

33
Q

Inhibitory signals

A

Make the neuron less likely to fire

34
Q

Excitatory signals

A

Make the neuron more likely to fire

35
Q

Passive signaling

A

sensory stimulation or synaptic activity opens ion channels

generates electrical current

36
Q

Graded Potential

A

Small voltage fluctuations in the cell membrane, passively conducted throughout the neuron.

Part of passive signaling

37
Q

Tetraethylammonium (TEA)

A

Selectively blocks K+ channels

prevents hyperpolarization

38
Q

Tetrodotoxin

A

Selectively blocks Na+ receptors

prevents depolarization

39
Q

Passive signaling is important in producing…

A

action potentials

40
Q

Excitatory Postsynaptic Potential (EPSP)

A

brief depolarization of a neuron membrane in response to stimulation

Neuron is more likely to produce an action potential

41
Q

Inhibitory Postsynaptic Potential (IPSP)

A

brief hyperpolarization of a neuron membrane in response to stimulation

Neuron is less likely to produce an action potential

42
Q

Temporal Summation

A

summing of potentials that arrive at the axon hillock at different times

the closer together in time that they arrive, the greater the summation and possibility of an action potential

43
Q

Voltage-sensitive ion channels

A

-gated protein channel that opens or closes only at specific membrane voltages

44
Q

Hodgkin-Huxley Cycle

A

Synaptic or receptor potential -> Membrane depolarizes -> Voltage-gated Na+ channels open -> Na+ flows into neuron
Steps 2,3, and 4 repeat

45
Q

Nodes of Ranvier

A

-The only place where sodium ion channels are found
-Unmyelinated parts of axon

46
Q

Spatial summation

A

summing of potentials that occur at different parts of the cell

47
Q

Axon hillock

A

-rich in voltage-sensitive channels
-EPSPs and IPSPs are integrated here
-action potentials are initiated here

48
Q

Action potential regenerates along the _____

A

axon

49
Q

Initial depolarization phase mediated by ____

A

Na+

50
Q

Repolarization phase mediated by ____

A

K+

51
Q

Absolute refractory period

A

-new action potential cannot be elicited
-gate 2 of sodium channels closed (not voltage-sensitive)

52
Q

Relative refractory period

A

-increased electrical current required to produce another action potential
-potassium channels still open

53
Q

Saltatory conduction

A

propagation of an action potential at successive nodes of Ranvier

54
Q

Gap junctions

A

-ion channels in pre and postsynaptic membrane aligned
-rapid conduction of information

55
Q

Chemical synapses

A

-how most neurons communicated
-can be inhibitory or excitatory
-large variety of chemicals

56
Q

Transmission sequence

A
  1. transmitters cross the synaptic cleft and bind to postsynaptic receptors and cause an EPSP or an IPSP
  2. EPSP or IPSP spread toward postsynaptic axon hillock
  3. axon potential travels down the axon
  4. Voltage gated calcium channels open and let in Ca 2+
  5. Synaptic vesicles fuse with membrane and release transmitter into cleft
57
Q

End plate

A

on a muscle, the receptor ion complex that is activated by the release of the neurotransmitter acetylcholine from the terminal of a motor neuron

58
Q

Acetylcholine

A

activated skeletal muscles

59
Q

Transmitter-sensitive channel

A

receptor complex that has both a receptor site for a chemical and a pore through which ions can flow

60
Q

Event related potential

A

large potential shifts caused by discrete stimuli
peaks and troughs are responses produced by the brain to specific stimuli

61
Q

Polarity of EEGs

A

positive does not mean an increase in activity and negative does not mean a decrease in activity

62
Q

What is used to determine the timing of a brain response?

A

EEG/neurophysiology

63
Q

What is used to determine the area a brain response is coming from?

A

Functional imaging

64
Q

MEG

A

Only sensitive to sources parallel to scalp surface (tangential)

65
Q

EEGs are sensitive everywhere, but most sensitive to ____ surfaces (parallel to the scalp

A

radial

66
Q

TMS

A

-electrical current running through tms coils produces magnetic field that can stimulate neurons
-can be used with neuroimaging methods to look at changes in brain activity
-can be used for treatment-resistant depression (after trying ketamine)

67
Q

What does an EEG measure

A

Post-synaptic membrane potentials (Jessica green repeated many times, will be on exam).

Intro to Neuroscience (14 decks)

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