SLE1/MODULE 2- Activation Signals Flashcards

1
Q

neuron is a type of ____

A

cell

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2
Q

where do neurons sit

A

extracellular fluid (ECF)

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3
Q

concentration gradient

A

refers to the movement of ions, into/out of the neuron

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4
Q

membrane potential

A

the change in potential across a cell membrane

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5
Q

resting membrane potential

A

no active signaling is occuring
-cell is at resting state

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6
Q

how do cells communicate

A

through membrane potential changes + movement of ions

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7
Q

resistance

A

how hard it is for an ion to cross the membrane

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8
Q

if there are a lot of doors/channels for the ion to go through, there is low/high resistance

A

LOW resistance
-high resistance if there are few channels

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9
Q

movement of ions causes ____

A

depolarizaition/hyperpolarization

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10
Q

depolarization

A

becoming more positive

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11
Q

hyperpolarization

A

becoming more negative

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12
Q

what does cell depolarization/hyperpolarizaiton do

A

modulates the chances of neuronal discharge

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13
Q

the neuron rests at a positive/negative membrane potential

A

negative

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14
Q

how is resting membrane potential (RMP) disrupted

A

ionic flow

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15
Q

ionic flow

A

the diffusion of ions

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16
Q

ions typically flow in what direction

A

high to low concentration
-different if energy is inputted into the system

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17
Q

through what does diffusion occur

A

via resting channels that are constantly open

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18
Q

if a bunch of positive ions enter a cell, we have depolarized/hyperpolarized

A

depolarized

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19
Q

if a bunch of positive ions exit a cell, we have depolarized/hyperpolarized

A

hyperpolarized

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20
Q

if negative ions enter a cell, we have depolarized/hyperpolarized

A

hyperpolarized

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21
Q

if negative ions exit a cell, we have depolarized/hyperpolarized

A

depolarized

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22
Q

Na+ goes into/out of cell

A

into (influx)

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23
Q

K+ goes into/out of a cell

A

out of (efflux)

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24
Q

why do nerve + muscle cell membranes generate potential differences

A

to pass current or to store charged particles

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25
Q

what does the membrane consist of

A

-lipids
-proteins

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26
Q

what is the membrane also called

A

phospholipid bilayer

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27
Q

phospholipid bilayer is permeable/impermeable

A

almost impermeable
-very tightly bound + almost impermeable to ions
-ions that CAN cross the membrane do so through specialized proteins, called ion channels

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28
Q

another name for ion channels

A

conductors

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29
Q

conductors enable nerve + muscle cells to do what

A

transmit changes in membrane potential

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30
Q

lots of ion channels/conductors = low/high resistance = low/high conductance

A

low resistance + high conductance

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31
Q

if ions pass through ion channels in a certain direction, what will happen

A

memrbane potential will change

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32
Q

3 properties of ion channels

A

-conduct ions rapidly
-recognize + select specific ions
-most of them open + close (gating) in response to specific electrical, mechanical, or chemical stimuli

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33
Q

are channels specific to specific ions

A

YES
-only recognize specific ions
-won’t let just any ion through

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34
Q

4 primary types of ion channels

A

-ligand-gated
-phosphorylation-gated
-voltage-gated
-stretch or pressre-gated

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35
Q

ligand-gated ion channel

A

binding of a chemical transmitter
-chemical transmitter binds to ion channel to open/close

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36
Q

phosphorylation-gated ion channel

A

phosphorylation of protein
-protein gets a phosphate added on

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37
Q

voltage-gated ion channel

A

change in membrane potential
-open/close in response to changes in membrane potential
-MOST IMPORTANT

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38
Q

stretch or pressure-gated ion channels

A

mechanical stimulus
-mechanical stimulus occurs + the channel is responsive to that particular stimuli

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39
Q

ligand-gated channels

A

open when a chemical ligand binds to a receptor site to allow ion flow

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40
Q

voltage-gated channels

A

open when a voltage changes to allow ion flow

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41
Q

2 types of voltage-gated channels

A

-Na+ channels
-K+ channels

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42
Q

Na+ channels are slow/fast to open

A

fast

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43
Q

K+ channels are slow/fast to open

A

slow

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44
Q

leak channels

A

channels without gates
-ions can move however they like, freely
-cell can be at resting membrane potential with these channels because as things go in, the same amount go out at rest

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45
Q

leak channels are ____ at rest

A

active

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46
Q

leak channels are largely responsible for establishing what

A

resting membrane potential

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47
Q

leak channels have selective permeability to ____

A

K+
-but also some Na+ and Cl-

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48
Q

are leak channels enough to re-establish concentrations of ions after muscle activation on their own

A

no
-if an AP happened, concentrations deviate from normal + leak channels ARE NOT enough to re-establish the original concentrations prior to the AP

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49
Q

equation for calculating resting membrane potential

A

Goldman Hodgkin Katz equation (GHJ)

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50
Q

Goldman Hodgkin Katz equation considers what 3 primary ions

A

-sodium
-potassium
-chloride

THESE IONS ALL IMPACT RMP

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51
Q

why do we frequently see squid nerve in physiology

A

because it’s nervous system is very simplistic

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52
Q

what unit is cell membrane potential measured in

A

mV

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53
Q

concentration is indicated by what

A

[brackets]

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54
Q

what unit is concentration measured in

A

millimoles

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55
Q

cytoplasm

A

inside cell

56
Q

extracellular fluid

A

outside cell

57
Q

equilibrium potential

A

the ion’s “happy place”
-when the chemical + electrical forces are balanced for a given ion

KNOW THIS

58
Q

resting membrane potential for most neurons

A

about -65 or -70 mV

59
Q

what sets the RMP

A

combination of all the equilibrium potentials of each ion (K+, Na+, Cl-, Ca2+, A)
-KNOW that not just one of these ions creats the RMP but all of them do + each have different levels of say in contributing

60
Q

what ion has a BIG say in determining RMP compared to other ions

A

K+
-all contribute, but K+ has a stronger say

61
Q

K+ equilibrium potential

A

-75

62
Q

Na+ equilibrium potential

A

+55

63
Q

Cl- equilibrium potential

A

-60

63
Q

Ca2+ equilibrium potential

A

+145

64
Q

whic equation calculates the equilibrium potential of an ion

A

Nernst equation

65
Q

Nernst equation

A

includes concentration of ion inside the cell, concentration of ion outside the cell, temperature, constants
-the sign of the ion is taken into account

66
Q

when we have active signaling, what does the resting membrane potential become

A

membrane potential
-no longer resting

67
Q

resting membrane potential is calculated by ___

A

GHK

68
Q

resting membrane potential is influenced by what

A

the equilibrium potentials of indivdual ions

69
Q

equilibrium potentials of individual ions are calculated by ____

A

Nernst

70
Q

the movement of K+ and Na+ are active/passive at RMP

A

passive

71
Q

at RMP, the diffusion of K+ and Na+ is called what

A

leak currents
-aka through leak channels

72
Q

current

A

the flow of positive charges
-both the influx of Na+ into the cell + efflux of Cl- out of the cell

73
Q

both the influx of Na+ into the cell + efflux of Cl- out of the cell are described as ____

A

inward currents

74
Q

know that current refers to POSITIVE charges

A
75
Q

the diffusion of an ion across the membrane depends on what

A

balancing 2 forces
-chemical force
-electrical force

76
Q

chemical force

A

due to the concentration gradient
-ex: how much sodium there is inside vs outside

77
Q

electrical force

A

electrostatic force due to potential difference across the membrane
-has to do with the CHARGE

78
Q

net driving force

A

combination of chemical + electrical driving forces
-magnitude of force acting on an ion

79
Q

net driving force equation

A

NDF = membrane potential - equilirbium potential

80
Q

sign of net driving force indicates what

A

direction

81
Q

negative net driving force

A

ions are moving IN
-influx

82
Q

positive net driving force

A

ions are moving out
-efflux

83
Q

electro-chemical gradients:
flux of K+ ions across resting membrane depends on what

A

balance of outward chemical force + inward electrical force, as well as K+ membrane conductance (# of resting channels)

84
Q

if there is a lot more K+ on inside than out…

A

chemical force is outward for K+ at rest
-K+ concentration gradient drives K+ out of the cell

85
Q

if the inside of the cell is negative and K+ is positive…

A

there is an inward electrical force for K+
-since opposites attract with electrical charges

86
Q

cation

A

positive ion

87
Q

*See slide 17, image could be used on quiz

A
88
Q

opposites ___

A

attract
-likes repel

89
Q

conductance

A

has to do with # of channels/conductors
-impacts permeability aka ability of an ion to move across a membrane
-therefore has a say in membrane potential

90
Q

K+ has low/high conductance

A

high

91
Q

Na+ has low/high conductance

A

low

92
Q

Cl- has low/high conductance

A

medium

93
Q

Cl- current

A

no current because - charge
-current is only + charges

94
Q

leak channels are also called

A

resting channels

95
Q

are leak/resting channels enough to help re-establish concentrations of ions after muscle activation on their own

A

no
-needs sodium potassium pump

KNOW THIS

96
Q

what % pumps are active under resting conditions

A

5%

97
Q

concentration gradients generate what

A

RMP

98
Q

what does a cell need to passively diffuse its ions indefinitely

A

a mechanism to maintain the gradients
-like the sodium potassium pump

99
Q

Na+/K+ pump (sodium potassium pump)

A

a transmembrane protein that returns the ions to their regions of high concentration using ATP for energy

100
Q

active signaling

A

refers to an AP

101
Q

4 steps of sodium potassium pump

A

-the sodium potassium pump binds 3 sodium ions + a molecule of ATP

-the splitting of ATP provides energy to change the shape of the channel; the sodium ions are driven through the channel

-the sodium ions are release to the outside of the membrane + the new shape of the channel allows 2 potassium ions to bind

-release of the phosphate allows the channel to revert to its original form, releasing the potassium ions on the inside of the membrane

102
Q

sodium potassium pump:
the unequal transfer of the ions is in what net direction

A

net outward current

103
Q

sodium potassium pump:
the ELECTROGENIC action of the pump

A

the unequal transfer of the ions results in a net outward current that maintains the negative charge on the inside of the membrane

104
Q

sodium potassium pump location on membrane

A

spans entire membrane

105
Q

sodium potassium pump: binding sites for K+ are on outside/inside

A

outside

106
Q

sodium potassium pump: binding sides for Na+ are on outside/inside

A

inside

107
Q

sodium potassium pump: binding sites for ATP are on outside/inside

A

inside

108
Q

sodium potassium pump: what happens to ATP each cycle

A

ATP is hydrolyzed each cycle of the sodium potassium pump
-3 Na+ are removed from inside
-2 K+ are returned to inside

109
Q

sodium potassium pump moves K+ in/out and Na+ in/out

A

K+ in, Na+ out

110
Q

what causes the net outward current of the sodium potassium pump

A

the UNEQUAL transfer of K+ and Na+ ions
-this returns us back to the negative charge of the of the resting membrane

111
Q

RMP in mV

A

-65 or -70 mV

112
Q

threshold

A

the voltage the cell must get to in order to develop an AP

113
Q

EPSP

A

excitatory post-synaptic potential

114
Q

what happens right before AP returns to resting potential

A

big negative overshoot

115
Q

all or none

A

while a stimulus below the threshold will not produce a signal, all stimuli above the threshold will produce the same signal
-the amplitude + duration does not change
-a stimulus that doesn’t get to threshold will not produce any signal
-anything that hits threshold will 100% produce an AP

116
Q

steps of an AP

A

RMP ->
threshold level ->
depolarization ->
repolarization ->
hyperpolarization

117
Q

what happens at the threshold level step of an AP

A

-local potential change
-graded potential

118
Q

what happens at depolarization stage of an AP

A

opening of voltage gated Na+ channels

119
Q

what happens at repolarization stage of an AP

A

-closure of Na+ voltage gated channels
-opening of K+ voltage gated channels

120
Q

what happens at hyperpolarization stage of an AP

A

vtolage gated K+ channels remain open after the potential reaches resting level
-this is what causes the graph to dip BELOW threshold level

121
Q

depolarization is excitatory/inhibitory

A

excitatory
-membrane becomes less negative

122
Q

how does depolarization happen

A

-POSITIVE charged ions carry the current on the inside of the membrane so that the potential difference across the membrane is reduced
-enhances the ability of postsynaptic cell to generate an AP

123
Q

how does hyperpolarization happen

A

-NEGATIVE charged ions carry the current on the inside of the membrane so that the potential difference across the membrane is amplified
-decreases the ability of postsynaptic cell to generate an AP

124
Q

what is the primary communication system between the neuromuscular system + beyond

A

APs

125
Q

FDI

A

first dorsal interosseous muscle
-we love studying this muscle in humans because small size + doesn’t affect other muscles

126
Q

neuromuscular propagation

A

transformation of the nerve action potential into a muscle fiber AP

127
Q

what assists the propagation of the descending command

A

myelin

128
Q

signal down brain descending center -> spinal cord -> muscle contraction is ____

A

unilateral direction

129
Q

voluntary contractions have unilateral/bilateral direction

A

unilateral

130
Q

voluntary contractions have ____

A

refractory period

131
Q

refractory period

A

think of slug analogy
-there is a period for APs where no other APs can occur until fully reset
-because things in nervous system move so fast, there is no problem with this

132
Q

continuous conduction

A

signals have no blocks/bumps/nodes to jump over

133
Q

saltatory conduction

A

signals jump from 1 node to another to another
-comes from word “saltar” in Spanish- to jump
-looks like signal is jumping from parts of the neuron
-not ACTUALLY jumping, just looks like it because there are little nodes or segments of myelin that helps propagate signals faster/slower based on how much myelin there is

134
Q

*do we need to memorize Nernst equation? and GHK equation?

IF SO- see slide 27

A