Membrane Action Potential Flashcards
(86 cards)
1
Q
___ channels set up the equilibrium or membrane potential
A
Leak channels
2
Q
Movement of ion’s is always ___ through all channels
A
passive
3
Q
Ligand gated channels are isolated on
A
Dendrites and cell bodies
4
Q
Voltage gated channels are isolated on
A
axon
5
Q
Neuron to neuron synapse can be stimulatory, inhibitory, or both
A
Both
6
Q
Neuron to muscle fiber synapse can be stimulatory, inhibitory, or both
A
Stimulatory
7
Q
Types of glial cells
A
PNS and CNS
8
Q
PNS contains what types of cells?
A
Satellite and schwann cells
9
Q
CNS contains what types of cells?
A
Oligodendrocytes
Astrocytes
Microglia
Ependymal cells
10
Q
Ligand-gated channels are small/large and more/less selective
A
Larger
Less
11
Q
Gap-junction channels are small/large and more/less selective
A
Larger
Less
12
Q
What’s the electrical channel?
A
- Part of the gap-junction channel
- connects cells to each other and allows ions to move in any direction
- electrically links cells together
- Leak channels
13
Q
Voltage-gated channels allow how many ion types through?
A
1
14
Q
Voltage-gated channels are small/large and more/less selective
A
small
More
15
Q
NaK ATPase pump moves ions __ concentration gradient
A
against
16
Q
What can’t pass through the membrane?
A
Proteins (AA and peptides)
17
Q
Equilibrium potential
A
single ion moving through membrane
18
Q
Electromotive force
A
When the neg charge on side I starts pulling back on that side b/c the other side is more positive
19
Q
Nernst equation
A
20
Q
monovalent cation X+ equation
A
21
Q
Monovalent anion Y- equation
A
22
Q
Average neuron is ___ mV charge within a cell
A
-70 mV
23
Q
Ek = ___ mV
A
-90
24
Q
ENa = ___ mV
A
+60
25
ECl = ___ mV
-70
26
ECa = ___ mV
+90
27
Describe membrane potential
Na+ and K+ going through/out of cell simultaneously
28
voltage gated and ligand gated channels do/don't contribute to resting membrane potential
don't
29
membrane potential's changed due to
Leak channels
30
Leak channels are always open/closed/partially open
Open
31
it takes ___ ions to create small negative charge in membrane
few ions
32
Goldman equation for finding resting membrane potential
33
PK, PNa and PCl permeability at rest
1, 0.01, and 0.45
34
__ Na+ go into cell and ___ K+ go out of cell
3
2
35
Graded potential is also called what
local potential
electratonic potential
36
as Na+ moves further from where it enters the ligand gated channels, it gets more/less charge as you move further through the postsynaptic neuron
Less
37
time constant equation
time constant = rm x capacitance
38
What does time constant measure?
a measure of how fast the charge changes when gates open
39
Graded potential is through ___ gated channels
ligand
40
action potential is through ___ gated channels
voltage
41
If there's a smaller time constant, there is ___ depolarization with ___ slope
Rapid
Steep
42
Presynaptic neurons act
the same
43
Larger time constant has a ___ change in charge
slow
44
Resting membrane potential's caused by
leak channels
45
Threshold of voltage gated channels is due to
ligand gated channels opening
46
depolarization = cell becomes more pos/neg
positive
47
repolarization = cell becomes more pos/neg
negative
48
What are the steps for activation and inactivation in voltage gated Na+ channels
1. at rest = activation gate closed and inactivation gate opened
2. activation = activation gate opens
3. inactivation = inactivation gate closes
4. goes back to rest = activation gate closed and inactivation gate open
49
Activation gate shuts due to
below threshold
50
Inactivation gate's not affected/affected by voltage
Not affected
51
Inactivation of voltage gated Na+ is due to
conformational change in protein
52
Do Na+ or K+ channels open slower
K+
53
Describe absolute refractory period
- Period during AP
- neuron doesn't fire another AP
- Channels fully open or closed
- area above threshold where you can't reactive voltage gated Na+ channels
54
Describe relative refractory period
- neuron can fire another AP but requires more stimulus
- AP is due to voltage gated Na+ channels
- Few voltage gated Na+ channels are back to the basal state (resting state)
--- Inactivation gate open and activation gate shut
55
What affects amplitude?
- ENa+
- How long voltage gated channels are open
- Conductance
56
What does voltage gate allow for?
- Allows us to determine # of ions flowing through voltage gated channels
57
negative vs. positive current
negative = positive ions go into cell
positive = positive ions goes out of cell
58
Current equation
current = conductance (g) x voltage (V)
59
Voltage equation
Voltage = current (I) x resistance (R)
60
Conductance equation
conductance (g) = 1 / resistance (R)
61
Driving force equation for inward sodium current
62
Driving force equation for outward potassium current
63
Do cations have outward or inward flow of ions?
outward
64
Do anions have outward or inward flow of ions?
Inward
65
What is tetrodotoxin?
It blocks voltage gated Na+ channels
- No depolarization
66
What is tetraethylammonium?
It blocks voltage gated K+ channels
- No repolarization
67
What is the voltage clamp equation and describe
- Pronase + TEA
- Uses instrument to make inside of neuron reach threshold and once it reaches threshold, Na+ channels open (activation gate opens) and stays open until you get below threshold
68
PK, PNa, and PCl value when voltage gated Na+ channels are open
PK = 1
PNa = 20
PCl = 0.45
69
___ is the decrease in strength over distance. Does this occur in graded or action potential?
Decremental
Graded potential
70
An axon is at rest w/ electrode stuck in the middle of an axon, and you stimulate the inside of the axon to threshold, does the AP move in 1 or both directions? Why?
Both b/c none of the voltage gated Na+ channels are in refractory
- It can be stimulated anywhere along the axon
71
During the absolute refractory period, does the AP move in 1 or both directions? Why?
1 direction (unidirectional)
Only in front of the AP do you have voltage gated channels being stimulated
72
___% decline in voltage when using the length constant
63%
73
What is spacial summation?
When you have 2 synapses pumping in Na+ there is a longer length constant that allows Na+ to travel further before it's diluted and it's more likely to reach the voltage gated channels and fire an AP
- Na+ more likely to reach voltage gated channels at axon hillock
74
Length constant equation
square root (rm/ri)
75
Do you need to have a larger or smaller length constant for Na+ to travel further?
Longer
76
Increasing length constant increases membrane resistance. How?
Myelin sheath b/c ions can't leave membrane
77
Decreasing internal resistance ___ axon size
increases
78
speed of action potential equation
length constant/time constant
79
bigger axons transport signals faster/slower
faster
80
Describe statutory conductance. Where are the voltage gated channels? How long can myelin sheaths be?
- when you have a myelin sheath axon, the AP jumps from node to node
- the voltage gated channels are only at the areas of exposed membrane along the axon
- myelin sheaths can't be too long b/c you need diffusion event to occur
81
Lidocaine inhibits what
voltage gated Na+ channels (temporarily)
82
A defect in Ca2+ channels causes. What happens?
malignant hyperthermia
- your body tells you to increase your body temp, which can be damaging if too high
83
Cystic fibrosis is a ___ gated channel mutation
Ligand
84
A defect in Na+ channels causes
Atypical myotonia
85
Myasthenia gravis is due to a ___ gated channel mutation. What happens?
- ligand
- Ach (which normally binds to ligand to open Na+ channels) doesn't allow Na+ to enter which blocks the neurotransmitter and prevents the normal neurotransmitter from binding, so muscles don't contract
86
What are the 2 types of Ach channels?
- Ach channels binds Ach and nicotine
- Ach channels binds Ach and muscarine
