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neurobiology > Neurobio Exam 1 Class notes > Flashcards

Neurobio Exam 1 Class notes Flashcards

1
Q

How are ion channels studied?

A

bc ion channels are too small to be visible under a light microscope, an electron microscope must be used

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2
Q

How does an electron microscope work?

A

electrons are shined through electromagnets and looked through at a sample through an electron detector.

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3
Q

How is the cell membrane structured?

A

it’s structured in the phospholipid-bilayer. this is structured in hydrophilic heads on the outside and hydrophobic tails on the inside. This allows the cell membrane to be selective with what it allows in and out of the cell.

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4
Q

Why are ion channels needed?

A

ions don’t permeate cell membranes. ions channels allows ions to pass through the membrane by creating a link

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5
Q

a positive ion

A

cation

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6
Q

a negative ion

A

anion

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7
Q

how does the ion channel work?

A

it can be activated to open or close its gate by plugging or blocking it.

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8
Q

Draw an open gate

A
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9
Q

what two ways can channels be activated?

A

they can be activated through physical changes in the cell membrane (voltage-activated or mechanically-activated) or they can be activated by ligands

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10
Q

draw a voltage-activated channel

A
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11
Q

draw a closed gate

A
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12
Q

draw the phospholipid-bilayer

A
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13
Q

what channels can be physically opened?

A

mechanic-activated

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14
Q

how does a ligands activated channel work?

A

a ligand will either attach to the outside of the cell for extracellular activation or the inside of the cell for intracellular activation.

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15
Q

what 2 channels are activated by physical changes?

A

voltage-activated and mechanically-activated channels

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16
Q

draw an intracellular activated ligand channel

A
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17
Q

draw an extracellular activated ligand channel

A
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18
Q

How are ion channels structured?

A

they are made of strings of amino acids with patterns of hydrophobic and hydrophilic molecules to allow to filter out. (ex a string of phobic,philic,phobic,philic,phobic,philic) when the strings are looped, it creates one side that is hydrophilic and the other side that is hydrophobic.

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19
Q

How does an ion channel open?

A

through molecular tremors

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20
Q

what are molecular tremors?

A

a dynamic shaking that results in the letting ions in and out of the ion channel

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21
Q

what is voltage in terms of ions?

A

the force/pressure that pushes ions out

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22
Q

what is amps in terms of ions?

A

how many ions are moving across channels

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23
Q

Patch Clamping recording

A

an electrode tip is applied to the cell and forms a gigaohm seal

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24
Q

inside out patch in patch clamping exp

A

you can tear/pull off the pipette

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25
Q

what patch clamping exp allows access/control to different sides of the channels

A

inside out cells, outside out patch, and whole-cell recording

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26
Q

whole-cell recording patch clamp exp

A

if more suction is applied, cell ruptures inside the pipette and cell becomes one with the pipette

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27
Q

outside-out patch in patch clamp exp

A

pulling/tearing after whole-cell recording phase

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28
Q

Gigaohm seal

A

cell-attached patch

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29
Q

How can we approach the complexity of the NS system?

A

we can look at the “simple” systems. Ex. visual system, anatomy
we can classify components of the NS
ex cell types : motion neurons, glial cells
we can classify connection types:
divergent signals, convergent signals, feedback loops, synchronized
we can measure things and do experiments
ex. imaging, electroimaging

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30
Q

because neurons are still cells…

A

they require certain components to function

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31
Q

father of neuroscience

A

Santiago Ramon y Cajal

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32
Q

how was Santiago Ramon y Cajal able to draw pictures of the cell?

A

using the golgi stainging method. Because the staining wasn’t perfect, he was able to see the networks

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33
Q

how does the photoreceptor work in basic terms

A

light hits the photoreceptor which in turn sends a message by releasing ions and stimulating the bipolar cell

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34
Q

electrical recording techniques

A

extracellular recording: measures firing from outside the cell
intracellular recording: measures specifically what one neuron is doing
whole cell patch recording: sucks cell into a capillary and gives access to control and measures the cell

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35
Q

what do intracellular recording and patch recording have in common?

A

-they use a capillary
-both, the cells die once capillary is removed

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36
Q

what is the currency of the NS?

A

electricity

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37
Q

resting potential is always…

A

negative

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38
Q

depolarization

A

brings the cell to a positive voltage

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39
Q

hyperpolarization

A

brings the cell to an even lower negative voltage

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39
Q

local graded potential

A

has a gradient response

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40
Q

what happens if local graded potential meets threshold?

A

an action potential

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41
Q

action potential is considered all-….

A

all or nothing. it is not a gradient

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42
Q

how is action potential measured?

A

by frequency

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43
Q

inhibitory signals happen when a cell is

A

hyperpolarized

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44
Q

excitatory signals happen when a cell is

A

depolarized

45
Q

equilibrium potential

A

the potential that just balances the concentration gradient of and ion where ions aren’t leaving or entering the cell

46
Q

equilibrium potential is controlled by the ____ but can be manipulated by changing the ____

A

concentration gradient, voltage

47
Q

Nerst Equation for potassium

A

E(k) = 58log ([K]outside)/([K]inside)

48
Q

what does the Nerst equation measure?

A

the equilibrium potential

49
Q

potassium has a big impact on the ___ of the cell

A

equilibrium

50
Q

Why do squids have a Squid Giant Axon

A

it requires a large action potential to create a large movement and therefore need a large axon

51
Q

why is the squid giant axon easy to study

A

it is giant and visible to the naked eye

52
Q

who studied the squid giant axon and won a nobel prize for their discovery?

A

Huxley and Hodgkin

53
Q

at high concentrations, potassium influences the potential, but at low concentrations ___

A

it doesn’t, Sodium does

54
Q

why does the Sodium-potassium pump contribute to the voltage of the cell?

A

because it pumps out 3 sodiums and pumps in 2 potassiums, therefore not balanced electrically. **it’s not pumping in as much as it’s pumping out

55
Q

what can the voltage clamp do?

A

-can measure voltage and current
-command voltage by making up the difference in voltage needed for action potential
-can depolarize or hyperpolarize the cell and hold it there
-tells us magnitude and direction of current

56
Q

how does the voltage clamp work in simple terms?

A

by clamping the membrane at a specific voltage and measuring the current

57
Q

who used the voltage clamp?

A

Huxley and Hodgkin

58
Q

what 3 currents did the voltage clamp exp. discover?

A

capacitative current
early current
late current

59
Q

what happens during capacitative current?

A

ions rearrange quickly

60
Q

what happens during the early current?

A

sodium rushes into the cell

61
Q

what happens during the late current

A

potassium rushes out of the cell

62
Q

late current - capacitative current = ?

A

early current

63
Q

what ion channel does TTX (puffer fish toxin) block?

A

sodium ion channel

64
Q

what ion channel does TEA toxin block?

A

potassium ion channel

65
Q

what happens to the current of Na+ and K+ during hyperpolarization?

A

they don’t respond (inhibition)

66
Q

what happens to the current of Na+ and K+ as depolarization increases?

A

the current increases allowing Na+ to flow into the cell and K+ to flow out of the cell (excitation)

67
Q

What happens to Na+ and K+ current at some point of increase in depolarization?

A

Na+ current stops increasing, K+ continues to increase, then Na+ current decreases causing an opposite outward flow of Na+ while K+ continues to increase

68
Q

What is happening when Na+ current stops increasing?

A

Na+ has reached equilibrium potential, causing the sodium channels to close and become inactive. Here Na+ cannot flow in or out of the cell

69
Q

What is the voltage of Na+ equilibrium potential?

A

+52 mV

70
Q

what does the flow of current depend on?

A

voltage, conductance, and the ion channels themselves

71
Q

What does I=GV represent?

A

it represents the relationship between the current and its dependence on conductance and voltage
I= current (amps)
G= conductance (G=1/R )
(R= resistance)
V= voltage

72
Q

describe the conductance of Na+ during the action potential

A

starts quickly and ends quickly

73
Q

describe the conductance of K+ during the action potential

A

starts slowly and continuously increases
- almost starts as Na+ current ends

74
Q

what is conductance?

A

the speed at which ions are flowing in or out of the cell

75
Q

Describe the current of Na+ and K+ during action potential

A

Na+ increases, K+ decreases

76
Q

what causes the capacitative current?

A

the gating current of the sodium-potassium channel

77
Q

describe the model that explains how a voltage gate opens

A

gate is opened by attracting positive amino acids
-when current shifts, gate opens due to change in charged particle

78
Q

Threshold

A

when sodium conductance overcomes potassium leak

79
Q

refractory period

A

a period where the membrane can’t make new action potentials right away

80
Q

absolute refractory

A

inactivation of sodium channels blocks future depolarization

81
Q

relative refractory

A

large activation of K+ channels need larger Na+ activation to overcome

82
Q

describe the ball-and-chain model of inactivation

A

this is how sodium channels are able to open quickly and close quickly. a particle from the gate plugs the entry

83
Q

Why does current move differently through axons?

A

because axons are not spheres

84
Q

how does current flow through the axon?

A

it diffuses along the cell membrane further away from the center of where the current started

85
Q

why is the axon directional?

A

because of the refractory period

86
Q

what influences the speed of the signal from the action potential in the axon?

A

the diameter of the axon itself and if it is myelinated (insulated)

87
Q

describe the axon in terms of its parts

A

insulated myelin chunks and nodes of ranvier

88
Q

What does this physiological feature of myelin and node of ranvier add to the axons?

A

allows propagation to jump from one node to another allowing for quicker and more efficient action potential at a higher frequency

89
Q

what do gap junctions allow neurons to do?

A

allows for good synchronicity

90
Q

what does the speed of the action potential in the dendrites rely on?

A

calcium potential, it has the ability to stimulate an action potential in the dendrites that will spread to another cell body

91
Q

what was the voltage clamp experiment used to observe?

A

it was used to dissect the action potential

92
Q

what ions are concentrated at nodes of ranvier?

A

Na+ ions

93
Q

connexons

A

connects to cells together in the gap junction

94
Q

passive transport

A

doesn’t require energy

95
Q

active transport

A

requires energy, typically ATP

96
Q

what are the two types of passive transports?

A

simple diffusion and facilitated diffusion

97
Q

simple diffusion

A

net flow of matter from a region of high concentration to a region of low concentration

98
Q

facilitated diffusion

A

like simple diffusion but occurs at a cell membrane and uses a transport molecule
ex: an ion channel

99
Q

what are the two types of active transport?

A

primary active transport and secondary active transport

100
Q

primary active transport

A

uses ATP to transport ions against their electrochemical gradients

101
Q

secondary active transport

A

uses the potential energy of another ion’s gradient

102
Q

what type of transport is the sodium-potassium pump?

A

primary active transport, it requires ATP

103
Q

what happens when the snail neuron was injected with sodium? what about with lithium?

A

the cell become hyperpolarized, nothing happened without sodium

104
Q

what does the snail experiment suggest?

A

that the sodium-potassium pump contributes to an action potential
the pump has a charge that reacts to Na+

105
Q

what is the charge of the sodium-potassium pump?

A

1/3 amount of Na+ (related to the pump releasing 3Na+ and receiving 2K+)

106
Q

Describe the model for ion translocation of the sodium-potassium pump

A

A) 3Na+ leave, 2K+ enter the cell
the gate is open facing inside of the cell. It is ATP bound and has an affinity for Na+
B) ATP loses a charge, loses ADP
C) Pump shifts and opens facing the outer cell
D) Na+ is kicked out into the outside of the cell concentration
and now the binding site has an affinity for K+
E) K+ binds to the site and loses a phosphate group
F) Gate shifts and opens inwardly again and ATP binds
A2) K+ is released inside the cell concentration and pump now has an affinity for Na+

107
Q

what is a huge consumer of ATP?

A

sodium-potassium pump

108
Q

Calcium ion transport want Calcium in or out of the cell?

A

out of the cell

109
Q

what type of transport is calcium transport?

A

it can be either facilitated diffusion or secondary active transport, depending on the mode of transport

110
Q

what type of transport is Chloride transport?

A

secondary active transport. It uses Na+ to co-transport Cl- into the cell and K+ to co-transport Cl- out of the cell

neurobiology (6 decks)

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