SLE1/MODULE 2- Activation Signals Flashcards
1
Q
neuron is a type of ____
A
cell
2
Q
where do neurons sit
A
extracellular fluid (ECF)
3
Q
concentration gradient
A
refers to the movement of ions, into/out of the neuron
4
Q
membrane potential
A
the change in potential across a cell membrane
5
Q
resting membrane potential
A
no active signaling is occuring
-cell is at resting state
6
Q
how do cells communicate
A
through membrane potential changes + movement of ions
7
Q
resistance
A
how hard it is for an ion to cross the membrane
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
9
Q
movement of ions causes ____
A
depolarizaition/hyperpolarization
10
Q
depolarization
A
becoming more positive
11
Q
hyperpolarization
A
becoming more negative
12
Q
what does cell depolarization/hyperpolarizaiton do
A
modulates the chances of neuronal discharge
13
Q
the neuron rests at a positive/negative membrane potential
A
negative
14
Q
how is resting membrane potential (RMP) disrupted
A
ionic flow
15
Q
ionic flow
A
the diffusion of ions
16
Q
ions typically flow in what direction
A
high to low concentration
-different if energy is inputted into the system
17
Q
through what does diffusion occur
A
via resting channels that are constantly open
18
Q
if a bunch of positive ions enter a cell, we have depolarized/hyperpolarized
A
depolarized
19
Q
if a bunch of positive ions exit a cell, we have depolarized/hyperpolarized
A
hyperpolarized
20
Q
if negative ions enter a cell, we have depolarized/hyperpolarized
A
hyperpolarized
21
Q
if negative ions exit a cell, we have depolarized/hyperpolarized
A
depolarized
22
Q
Na+ goes into/out of cell
A
into (influx)
23
Q
K+ goes into/out of a cell
A
out of (efflux)
24
Q
why do nerve + muscle cell membranes generate potential differences
A
to pass current or to store charged particles
25
what does the membrane consist of
-lipids
-proteins
26
what is the membrane also called
phospholipid bilayer
27
phospholipid bilayer is permeable/impermeable
almost impermeable
-very tightly bound + almost impermeable to ions
-ions that CAN cross the membrane do so through specialized proteins, called ion channels
28
another name for ion channels
conductors
29
conductors enable nerve + muscle cells to do what
transmit changes in membrane potential
30
lots of ion channels/conductors = low/high resistance = low/high conductance
low resistance + high conductance
31
if ions pass through ion channels in a certain direction, what will happen
memrbane potential will change
32
3 properties of ion channels
-conduct ions rapidly
-recognize + select specific ions
-most of them open + close (gating) in response to specific electrical, mechanical, or chemical stimuli
33
are channels specific to specific ions
YES
-only recognize specific ions
-won't let just any ion through
34
4 primary types of ion channels
-ligand-gated
-phosphorylation-gated
-voltage-gated
-stretch or pressre-gated
35
ligand-gated ion channel
binding of a chemical transmitter
-chemical transmitter binds to ion channel to open/close
36
phosphorylation-gated ion channel
phosphorylation of protein
-protein gets a phosphate added on
37
voltage-gated ion channel
change in membrane potential
-open/close in response to changes in membrane potential
-MOST IMPORTANT
38
stretch or pressure-gated ion channels
mechanical stimulus
-mechanical stimulus occurs + the channel is responsive to that particular stimuli
39
ligand-gated channels
open when a chemical ligand binds to a receptor site to allow ion flow
40
voltage-gated channels
open when a voltage changes to allow ion flow
41
2 types of voltage-gated channels
-Na+ channels
-K+ channels
42
Na+ channels are slow/fast to open
fast
43
K+ channels are slow/fast to open
slow
44
leak channels
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
45
leak channels are ____ at rest
active
46
leak channels are largely responsible for establishing what
resting membrane potential
47
leak channels have selective permeability to ____
K+
-but also some Na+ and Cl-
48
are leak channels enough to re-establish concentrations of ions after muscle activation on their own
no
-if an AP happened, concentrations deviate from normal + leak channels ARE NOT enough to re-establish the original concentrations prior to the AP
49
equation for calculating resting membrane potential
Goldman Hodgkin Katz equation (GHJ)
50
Goldman Hodgkin Katz equation considers what 3 primary ions
-sodium
-potassium
-chloride
THESE IONS ALL IMPACT RMP
51
why do we frequently see squid nerve in physiology
because it's nervous system is very simplistic
52
what unit is cell membrane potential measured in
mV
53
concentration is indicated by what
[brackets]
54
what unit is concentration measured in
millimoles
55
cytoplasm
inside cell
56
extracellular fluid
outside cell
57
equilibrium potential
the ion's "happy place"
-when the chemical + electrical forces are balanced for a given ion
KNOW THIS
58
resting membrane potential for most neurons
about -65 or -70 mV
59
what sets the RMP
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
what ion has a BIG say in determining RMP compared to other ions
K+
-all contribute, but K+ has a stronger say
61
K+ equilibrium potential
-75
62
Na+ equilibrium potential
+55
63
Cl- equilibrium potential
-60
63
Ca2+ equilibrium potential
+145
64
whic equation calculates the equilibrium potential of an ion
Nernst equation
65
Nernst equation
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
when we have active signaling, what does the resting membrane potential become
membrane potential
-no longer resting
67
resting membrane potential is calculated by ___
GHK
68
resting membrane potential is influenced by what
the equilibrium potentials of indivdual ions
69
equilibrium potentials of individual ions are calculated by ____
Nernst
70
the movement of K+ and Na+ are active/passive at RMP
passive
71
at RMP, the diffusion of K+ and Na+ is called what
leak currents
-aka through leak channels
72
current
the flow of positive charges
-both the influx of Na+ into the cell + efflux of Cl- out of the cell
73
both the influx of Na+ into the cell + efflux of Cl- out of the cell are described as ____
inward currents
74
know that current refers to POSITIVE charges
75
the diffusion of an ion across the membrane depends on what
balancing 2 forces
-chemical force
-electrical force
76
chemical force
due to the concentration gradient
-ex: how much sodium there is inside vs outside
77
electrical force
electrostatic force due to potential difference across the membrane
-has to do with the CHARGE
78
net driving force
combination of chemical + electrical driving forces
-magnitude of force acting on an ion
79
net driving force equation
NDF = membrane potential - equilirbium potential
80
sign of net driving force indicates what
direction
81
negative net driving force
ions are moving IN
-influx
82
positive net driving force
ions are moving out
-efflux
83
electro-chemical gradients:
flux of K+ ions across resting membrane depends on what
balance of outward chemical force + inward electrical force, as well as K+ membrane conductance (# of resting channels)
84
if there is a lot more K+ on inside than out...
chemical force is outward for K+ at rest
-K+ concentration gradient drives K+ out of the cell
85
if the inside of the cell is negative and K+ is positive...
there is an inward electrical force for K+
-since opposites attract with electrical charges
86
cation
positive ion
87
*See slide 17, image could be used on quiz
88
opposites ___
attract
-likes repel
89
conductance
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
K+ has low/high conductance
high
91
Na+ has low/high conductance
low
92
Cl- has low/high conductance
medium
93
Cl- current
no current because - charge
-current is only + charges
94
leak channels are also called
resting channels
95
are leak/resting channels enough to help re-establish concentrations of ions after muscle activation on their own
no
-needs sodium potassium pump
KNOW THIS
96
what % pumps are active under resting conditions
5%
97
concentration gradients generate what
RMP
98
what does a cell need to passively diffuse its ions indefinitely
a mechanism to maintain the gradients
-like the sodium potassium pump
99
Na+/K+ pump (sodium potassium pump)
a transmembrane protein that returns the ions to their regions of high concentration using ATP for energy
100
active signaling
refers to an AP
101
4 steps of sodium potassium pump
-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
sodium potassium pump:
the unequal transfer of the ions is in what net direction
net outward current
103
sodium potassium pump:
the ELECTROGENIC action of the pump
the unequal transfer of the ions results in a net outward current that maintains the negative charge on the inside of the membrane
104
sodium potassium pump location on membrane
spans entire membrane
105
sodium potassium pump: binding sites for K+ are on outside/inside
outside
106
sodium potassium pump: binding sides for Na+ are on outside/inside
inside
107
sodium potassium pump: binding sites for ATP are on outside/inside
inside
108
sodium potassium pump: what happens to ATP each cycle
ATP is hydrolyzed each cycle of the sodium potassium pump
-3 Na+ are removed from inside
-2 K+ are returned to inside
109
sodium potassium pump moves K+ in/out and Na+ in/out
K+ in, Na+ out
110
what causes the net outward current of the sodium potassium pump
the UNEQUAL transfer of K+ and Na+ ions
-this returns us back to the negative charge of the of the resting membrane
111
RMP in mV
-65 or -70 mV
112
threshold
the voltage the cell must get to in order to develop an AP
113
EPSP
excitatory post-synaptic potential
114
what happens right before AP returns to resting potential
big negative overshoot
115
all or none
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
steps of an AP
RMP ->
threshold level ->
depolarization ->
repolarization ->
hyperpolarization
117
what happens at the threshold level step of an AP
-local potential change
-graded potential
118
what happens at depolarization stage of an AP
opening of voltage gated Na+ channels
119
what happens at repolarization stage of an AP
-closure of Na+ voltage gated channels
-opening of K+ voltage gated channels
120
what happens at hyperpolarization stage of an AP
vtolage gated K+ channels remain open after the potential reaches resting level
-this is what causes the graph to dip BELOW threshold level
121
depolarization is excitatory/inhibitory
excitatory
-membrane becomes less negative
122
how does depolarization happen
-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
how does hyperpolarization happen
-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
what is the primary communication system between the neuromuscular system + beyond
APs
125
FDI
first dorsal interosseous muscle
-we love studying this muscle in humans because small size + doesn't affect other muscles
126
neuromuscular propagation
transformation of the nerve action potential into a muscle fiber AP
127
what assists the propagation of the descending command
myelin
128
signal down brain descending center -> spinal cord -> muscle contraction is ____
unilateral direction
129
voluntary contractions have unilateral/bilateral direction
unilateral
130
voluntary contractions have ____
refractory period
131
refractory period
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
continuous conduction
signals have no blocks/bumps/nodes to jump over
133
saltatory conduction
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
*do we need to memorize Nernst equation? and GHK equation?
IF SO- see slide 27
