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Anatomy > Neurophysiology > Flashcards

Neurophysiology Flashcards

1
Q

5 steps of neurons responding to stimuli and communicate with distant cells

A

Resting membrane potential
Graded potential
Action potential
Synaptic activity
Information processing

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2
Q

Resting membrane potential is what

A

transmembrane potential of resting cell
description of how ions are distributed

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3
Q

at resting membrane potential, what is the inside relative to the outside

A

negative

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4
Q

graded potential is what

A

temporary, localized changes in transmembrane potential
cell becomes less or more negative than before

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5
Q

to be meaningful, what change has to occur at a graded potential

A

a changed caused by a stimulus

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6
Q

when does an action potential occur

A

if the stimulus is great enough

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7
Q

what happens at action potential

A

reversal of membrane potential, so the inside is positive relative to the outside

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8
Q

what do action potentials continue along

A

the axon

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9
Q

what is synaptic activity

A

occurs once action potentials reach the terminal bouton, then neurotransmitters are released

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10
Q

information processing step has what

A

when neurotransmitters binds to receptor, then changes occur in postsynaptic cell

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11
Q

What does the cell membrane separate

A

charges
so ICF (-) and ECF (+)
the membrane is polarized

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12
Q

where does RMP occur

A

only in thin layer along cell membrane

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13
Q

what is the RMP in neurons or muscle fibers (mV)

A

-70 mV

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14
Q

what are the 2 points measured between for voltage

A

reference electrode and recording electrode

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15
Q

Is Na + ICF or ECF

A

ECF

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16
Q

is K+ ICF or ECF

A

ICF

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17
Q

What are the passive forces across membranes

A

chemical gradient
electrical gradient
electrochemical gradient

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18
Q

what is chemical gradient

A

a concentration gradient
where particles move down the conc gradient

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19
Q

what is the potassium chemical gradient

A

out

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20
Q

when does electrical gradient occur

A

if charges are separated

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21
Q

what is the electrochemical gradient determine

A

the direction that the ion moves if a channel opens

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22
Q

What can small electrical differences offset

A

large chemical differences

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23
Q

K electrical gradient is

A

IN

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24
Q

K concentration gradient is

A

OUT

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25
Q

K electrochemical gradient is

A

OUT

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26
Q

Na electrical gradient is

A

IN

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27
Q

NA concentration gradient is

A

IN

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28
Q

NA electrochemical gradient is

A

IN

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29
Q

If allowed, how do particles move

A

down their electrochemical gradient

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30
Q

Ions only cross a membrane if what

A

if channel or carrier is present in membrane

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31
Q

steps of resting membrane potential

A

na tends to leak in
k tends to leak out
lots of channels for Cl - to move near equilibrium
anionic proteins are trapped inside cell

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32
Q

examples of active transport

A

Na/K pump

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33
Q

what does the Na/K pump use and to do what

A

uses ATP to move ions againnst electrochemical gradients

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34
Q

what is the equilibrium potential used to determine

A

the directio of electrochemical gradient

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35
Q

equilibrium potential def

A

the transmembrane potential at which no net movement of a particular ion across the cell membrane

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36
Q

equilibrium potential simple def

A

net movement in=net movement out

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37
Q

electrical gradient is equal and opposite to the what for an ion in the equilibrium potential

A

to the chemical gradient

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38
Q

if the channel opens, where do ions move

A

in the direction that pulls Vm toward E

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39
Q

What is changing membrane potentials def

A

alter membrane potential by changin membrane permeability to certain ions

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40
Q

how do neurons and muscle cells change permeability

A

by opening or closing channels in membrane

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41
Q

what are the 3 gated channels

A

ligand gated
voltage gated
mechanically regulated

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42
Q

ligand gated channels are what

A

chemical that binds

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43
Q

when binding occurs in ligan gated channels, what happens

A

the channel opens

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44
Q

what breaks down acetylcholine

A

acetycholine esterase.
AchE breaks down Ach so that the channel closes

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45
Q

voltage gated channels, what happens at RMP

A

the activation gate is closed but the inactivation gate is open

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46
Q

if increase vM, what happens to gates

A

both gates open

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47
Q

if a lot of sodium enters a cell what happens

A

the pos voltage is achieved and this causes inactivation gate to close

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48
Q

mechanically regulated channels is what

A

distorting cell membrane by physically pressing on it so that the channel opens

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49
Q

transmembrane potential exists across cell membranes because why?

A

ICF and ECF have different chemical/ion balances

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50
Q

Graded potention is a deviation from what

A

RMP due to stimulus

51
Q

Magnitude is proportional to what

A

Stimulus intensity

52
Q

when the cell is stimulated, what happens

A

na channels open,
so na rushes in
cell becomes more positive/less negative

53
Q

what type of changes does graded potential enact

A

local changes only

54
Q

how far does graded potential travel

A

short distances

55
Q

where do sodium ions sit

A

they dont, they diffuse along membrane

56
Q

depolarization is what

A

when Vm becomes less negative/more positive

57
Q

what channels open during depolarization

A

sodium channels open so that Na rushes in
OR
potassium channels close so that less K exits out

58
Q

what happens during hyperpolarization

A

Vm becomes more negative/less positive

59
Q

what channels open during hyperpolarization

A

potassium channels open so that K exits the cell
OR
sodium channels close so that less sodium enters the cell

60
Q

why do transmembrane potentaisls change

A

due to altered membrane permeability in response to stimuli

61
Q

action potentials are what

A

rapid, dramatic change in transmembrane potental

62
Q

what happens ruing action potentials

A

Vm becomes positive, leads to a series
magnitude is similar
propagated without decrement

63
Q

are action potentials depolarization or hyperpolarization

A

depolarization … Vm becomes less negative

64
Q

what is a thrshold stimulus

A

a stimulus large enough to depolarize axon hillock to -60 mV

65
Q

what happens if graded potential is smaller?
Bigger?

A

smaller - no AP is generation
bigger- yes able to generate AP

66
Q

what does depolarizaing the cell membrane to threshold result in

A

the generation of an action potential

67
Q

how long does the action potential feedback loop occur until

A

until all voltage-gated sodium channels open

68
Q

what causes the rapid reversal of membrane potential to +50 mV

A

action potential

69
Q

how does membrane potential move to +50 mV

A

all voltage gated sodium channels need to open
pulling Vm toward ENA+

70
Q

why doesn’t the membrane potential reach ENA+

A

because voltage gated Na channels start to close when Vm reaches +30 mV

71
Q

when do voltage gated K+channels open

A

when Vm reaches about +30 mV

72
Q

At peak, waht happens to K+ and NA_-+

A

K+ begins rushing out and NA+ movement across membrane stops mostly

73
Q

what happens when K+ rushes out

A

it rushes out down its electrochemical gradient and toward EK+

74
Q

what is EK+

A

-90 mV

75
Q

what is the refractory period

A

time from beginning of action potential to return to resting state

76
Q

will membrane respond normally to additional stimulus during the refractory period

A

no

77
Q

can a 2nd AP be generated during absolute refractory period

A

no

78
Q

what happns during the relative refractory period

A

2nd AP can be generated, but it requires a larger stimulus and not as big as a normal AP

79
Q

Sodium channels during Absolute refractory period

A

sodicum channels open or inactivated
cell is still depolarizing, therefore…cant respond

80
Q

is additional AP possible during Absolute refractory period

A

not possible
Gates reset at about - 4o mV

81
Q

steps of a voltage regulated channel

A

RMP
threshold voltage where activation gate opens
inactivation gate closes, and activation gates still remains open

82
Q

what happens to the membrane potential during the relative refractory period

A

membrane potential is amost normal (between -40 mV and RMP)

83
Q

Stimulus information during relative refractory period

A

stimulus greater than threshold can initiate action potential
but a normal stimulus will not
this is because some NA+ channels haven’t reset yet
this counters efflux of K+

84
Q

what is the propagation of action potentials

A

series of action potentials along axon toward synaptic knob

85
Q

what is continuous conduction caused by

A

unmyelinated axons

86
Q

5 steps of continuous conduction

A
  1. AP depolarizes membrane to +30 mV
  2. local current depolarizes adjecent membrane to threshold (voltage gated Na channels open)
  3. generation of another AP
  4. cycle repears
  5. AP travles 1 m/sec
87
Q

why does Na move along membrane

A

to remove electrical gradient

88
Q

where is the location of voltage gated sodium channels

A

between cell body and axon

89
Q

steps of saltatory conduction (myelinated axons)

A
  1. action potential depolarizes membrane to +30
  2. local current depolarizes adjacent node to threshold (voltage gated Na open)
  3. generation of another action potential
  4. cycle repears
  5. AP travels 50 m/sec
90
Q

one way propagation of action potentials means what

A

as next area develops an action potential , the previous area is in refractory period

91
Q

transmembrane potential reverses if what

A

if threshold stimulus is reached

92
Q

series of AP are propagated toward what

A

axon terminal

93
Q

properties of AP result in what

A

one way nerve conduction

94
Q

what happens at the cholinergic synapse/what are they

A

all neuromuscular junctions with skeletal muscle
many synapses in CNS
all neuron to neuron synapses in PNS
all neuromuscular and nuroglandular junctions is PSNS

95
Q

what is the most common neurotransmitter

A

cholinergic synapse

96
Q

what is a chemical synapse example

A

its a neurotransmitter… ex is acetylcholine

97
Q

do reflexes have less or more synapses

A

less to make it faster

98
Q

what are the events at cholinergic synapse… 5

A

AP arrives at synaptic end knob
Depolarization of synaptic end knob
voltage gated Ca++ channels open
Ca++ enter synaptic knob
Trigger exocytosis of ACH
ACh binds to receptors on postsynaptic membrane
depolarization of postsynaptic membrane
AChE breaks ACh into acetate and choline

99
Q

what is the delay Cholinergic synapse

A

0.2 to 0.5 seconds

100
Q

what happens when AP arrives at synaptic end knob

A

sodium channels open

101
Q

what is it called when transmembrane potetential Vm becomes positive

A

Depolarization

102
Q

Ca++ influx moves how

A

down its electrochemical gradient

103
Q

what does cytoplasmic Ca++ cause synaptic vessicles to do

A

move along microtubules and fuse with cell membrane

104
Q

how whcih does ACHE break down ACH

A

within 20msec of binding to receptors

105
Q

as ACh drop in synaptic gap, what happens

A

they are not able to remain attached to its receptor

106
Q

what do nuerotransmitter direct

A

effects via ligand gated channels

107
Q

what is nicotinic

A

a chemical in cigarrettes that is addictivve

108
Q

what happens when ACh binds a receptor,

A

Na channels open, and then Na enters…. causing depolarization

109
Q

what are the 3 indirect effects via G proteins

A
  1. receptor binding of ligand activates G protein
  2. Activated G protein binds enzyme thus altering its activity
  3. production of second messenger
110
Q

what do G proteins do

A

bind GTP - active which can make GDP - inactive

111
Q

what do activated g proteins do

A

turns on or off

112
Q

where does cAMP accumulate

A

in cytoplasm

113
Q

how do enzymes change cell metabolism and activity

A

by adding/removing phosphates

114
Q

what does Nuerpiphrine bind

A

receptors

115
Q

what happens during the information processing stage

A

postsynaptic cell can recienve multiple stimuli

116
Q

why cna one cell receive multiple stimule

A

bcuz multiple presynaptic cells are coming in contact with it

117
Q

excitatory postsynaptic potential is what

A

depolarization: graded potential

118
Q

inhibitory postsynaptic potential is what

A

hyperpolarizaiton :graded potential

119
Q

what is summation

A

the summed influence of multiple inputs to determine if an AP occurs in postsynaptic cell

120
Q

what is spatial summation

A

simultaneous stimuli from multiple synapse

121
Q

what is temporal summation

A

send stimuli in rapid succession at single synapse

122
Q

what is the simplest form of information processing in the nervous system

A

a change in transmembrane potential that determines whether or not AP’s are generated

123
Q

What is An excitatory postsynaptic potential (EPSP)

A

is a temporary depolarization of the postsynaptic membrane that occurs when a neurotransmitter binds to receptors on a neuron

124
Q

what is An inhibitory postsynaptic potential (IPSP)

A

is a change in the electrical potential of a postsynaptic neuron that decreases the likelihood of an action potential:

Anatomy (18 decks)

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