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Neuro > Chapter 6 & 7 > Flashcards

Chapter 6 & 7 Flashcards

1
Q

What is the normal resting potential of a cell

A

-65 to -70 mV

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2
Q

What measures the resting potential of a cell

A

Oscilloscope

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3
Q

How does the oscilloscope measure the resting potential

A

One probe is in the intracellular fluid and the other is in the extracellular fluid

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4
Q

What are the major players in membrane and action potentials (5)

A
  1. K+
  2. Na+
  3. Cl-
  4. Ca++
  5. Proteins (A-)
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5
Q

Which of the major players are in greater concentration inside the cell (2)

A
  1. K+

2. A-

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6
Q

Which of the major players are in greater concentration outside the cell (3)

A
  1. Na+
  2. Cl-
  3. Ca++
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7
Q

What is equilibrium potential

A

A balance between diffusion and electrostatic pressure

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8
Q

What is the equation used to determine the equilibrium potential

A

Nernst equation

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9
Q

What is the Nernst equation

A

V= RT/zF ln([X]out/[X]in)

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10
Q

What is R

A

Gas constant 8.314

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11
Q

What is T

A

Temperature 298.15K (room temp)

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12
Q

What is F

A

Faraday’s constant 96500

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13
Q

What is z

A

Charge of ion

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14
Q

What are glial cells permeable to at rest

A

K+ only

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15
Q

What are neurons permeable to at rest

A

Na+ and K+

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16
Q

How many open channels are there for K+ and Na+ in a neuron (roughly)

A

K+: Many open channels

Na+: Only a few open channels

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17
Q

What does the Na+/K+ pump move

A

3 Na+ out and 2 K+ in

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18
Q

What is a graded potential

A

The stimuli is able to vary in size from small to big

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19
Q

What does depolarization at the dendrites give you

A

Only graded potentials

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20
Q

What does depolarization at the axon hillock/axon give you

A

Only action potentials

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21
Q

True or False:

A graded potential diffuses to nearby areas and leaks out of the neuron as it moves down the neuron

A

True

22
Q

Where does the signal need to go in order to initiate an action potential

A

Axon hillock

23
Q

What is an action potential

A

A nerve impulse that is an electrical signal that moves from the axon hillock down the axon to the terminal button

24
Q

What is it called when you send a signal from the axon hillock to the terminal button

A

Internal neuronal communication

25
Q

What are the 4 properties of an action potential

A
  1. Threshold
  2. All-or-none
  3. Does not diminish
  4. Followed by refractory period
26
Q

What is the threshold

A

The point at which an AP will occur when the graded potential is big enough

27
Q

What is all-or-none

A

When the threshold is met the action potential will be the same but if the threshold isn’t met no action potential is formed

28
Q

True or False:

The action potential is the exact same at the start and end of the axon

A

True

29
Q

What is the refractory period

A

Time during which an AP can’t occur or it is much harder to get an AP

30
Q

What are 2 critical voltage gated channels for causing an AP

A
  1. Na+

2. K+

31
Q

What happens when there is a conformational change in the voltage gated channel

A

An action potential occurs

32
Q

What causes a conformational change in the voltage gated channel

A

Positively charged amino acids moving inside the voltage gated channel do to a big enough graded potential

33
Q

What are 2 key differences between the Na+ and K+ voltage gated channels

A
  1. Na+ channel opens faster

2. Na+ channel becomes inactivated

34
Q

When are the Na+ channels deactivated based on the graph

A

At the peak of the graph

35
Q

What close the voltage gated Na+ channels

A

The ball and chain

36
Q

What prevents the neuron from getting to +55 mV which is the equilibrium potential of Na+

A

K+ prevents it

37
Q

What occurs once the Na+ channels close

A

K+ continues to leave the cell bringing the cell back to it’s negative potential

38
Q

What causes the over shoot

A

The remaining K+ outside the cell makes the inside of the cell negative making it briefly hyperpolarized

39
Q

What are the 6 steps of an action potential firing

A
  1. Na+ channels open and Na+ begins to enter the cell
  2. K+ channels open K+ begins to leave cell
  3. Na+ channels close so no more Na+ enters the cell
  4. K+ continues to leave the cell bringing the membrane potential back to normal
  5. K+ channels close and Na+ channels reset
  6. Extra K+ outside diffuses away
40
Q

What is the absolute refractory period

A

The period of time following an action potential during which no stimulus can initiate another action potential

41
Q

What mediates the absolute refractory period

A

The Na+ channels being inactivated by the ball and chain

42
Q

What is the relative refractory period

A

The period of time following an action potential during which an action potential can be initiated but only by a stronger than normal stimulus

43
Q

When does the relative refractory period occur

A

When the Na+ channels are de-inactivated (ball and chain is no longer closing channel)

44
Q

What are at the axon hillock the cause an action potential

A

Voltage gated Na+ channels

45
Q

Do dendrites have voltage gated Na+ channels

A

No

46
Q

What does myelin do to an axon

A

Makes the conduction of the AP faster because cells can’t leak out

47
Q

Where are there a lot of unmyelinated axons

A

Cerebrum

48
Q

Which pain neuron is myelinated and unmyelinated

A

Myelinated: Sharp pain
Unmyelinated: Dull pain

49
Q

How does MS prevent a neuron from conducting the impulse properly

A

The myelin on the neuron is lost and the AP diminshes because there are no voltage gated Na+ channels where the myelin was located.

50
Q

Card #50

A

Good luck on the test

Neuro (15 decks)

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