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Med310A > Lecture 3: Action Potential > Flashcards

Lecture 3: Action Potential Flashcards

1
Q

Common structures of neutrons:
1. Input zone: _____
2. Integration zone: _____
3. Point of action potential initiation: ____
4. Conducting zone: ____
5. Out put zone: _____

A

Dendrite
Cell body
Axon hillock
Axon
Axon terminal

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2
Q

An electrical signal that travels from one end of a cell to the other very rapidly

A

Action potential

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3
Q

___ allow fast information transfer within the body
________ mediate the rapid spread of information

A

Neurons
Action potential

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4
Q

Voltage different across plasma membrane =

A

Membrane potential

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5
Q

-50 to -70mV =

A

Resting membrane potential

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6
Q

The magnitude of the potential depends on the degree of separation of _____ ____

A

Opposite charges

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7
Q

Less potential = ___
More potential = ___

A

Depolarized
Hyperpolarized

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8
Q

Lipid bilayer is a good ___

A

Insulator

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9
Q

Electrical signals in neurons depend on rapid changes in ____

A

Membrane potentials

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10
Q

____ mediate the flow of ions (currents) that underlie electrical signals in excitable cells

A

Ion channels

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11
Q

Structure of ion channels:
___ span the membrane
Form ___ -filled pore

A

Proteins
Water

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12
Q

Properties of ion Chanels:
-act as filters allowing specific ___ through the cell membrane
- have ___ states and _____ states
- transition between states = gating
- > channels gate in response to:
-changes in _______ (____ - gated channels)
- ______ binding (____-gated or ___ operated channels)
- ____ forces (______ channels)

A

Ions
Conducting and non conducting
Gating
Membrane potential (voltage gated)
Ligand (ligand or receptor )
Mechanical (mechanosensitive )

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13
Q

Structure: Functional role:
___ and ___ Synaptic potential intrinsic excitability
—— Action potential generation
___ action potential conductance
________ Transmitter release

A

Dendrites and cell body
Axon hillock
Axon
Axon terminal

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14
Q

Rapid opening of voltage gated channel triggered at ___

A

Threshold

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15
Q

Na+ channels:
___ activating and inactivating
Inactivated channels cannot ____

K+ channels:
___ activating
Persistent ___

At rest Na+ and K+ channels are ___

A

Fast
Reopen
Slow
Activation
Closed

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16
Q

A triggered event induces membrane ___
Depolarization may activate some___ channels allowing __ influx
Causing more _____

A

Depolarization
Na+
Depolarization

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17
Q

___ = start of action potential (point of no return)

A

Threshold

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18
Q

Once the threshold is reached, _____ feedback cycle of ___ channel
activation begins.
• This cannot be stopped (thus
point of no return)
• This underlies _____
nature of action potentials

A

Positive
Na+
All-or-none

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19
Q

Around the peak of action potential, two things happen that stop further____ and start____

A

depolarization
repolarization

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20
Q

___ channels cannot open while in an inactive state. Therefore action potential cannot be elicited during this time

A

Na+

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21
Q

• Membrane
____ causes
both Na+ and K+
channels to return to
closed state
• Na+ and K+ channels
are available to___ at
next stimulation

A

Repolarization

Open

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22
Q

During afterhyperpolarization (AHP), it is harder to elicit an action potential because the membrane is more ____

A

hyperpolarized

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23
Q

Strong triggering stimulus
results in ___ frequency firing

A

High

24
Q

How do neurons fire action potentials in different patterns?

A

Neurons have various ion channels that can induce various firing patterns

25
Q

Action potential starts at the ____
and then propagate down the ___
• While propagating, action potentials do
no wane in _____
• This is because action potential is
____

A

Axon hillock
Axon
Size
Regenerative

26
Q

What are the Two functional roles of refractory period

A
  1. Prevent backward
    propagation of action
    potentials
  2. Limit firing frequency
27
Q

What ion channels underlie action potentials?

A

Na+ and K+ channels

28
Q

Where is action potential generated?

A

Axon hillock

29
Q

Why can an action potential travel long distance
without fail?

A

Because action potentials are regenerative

30
Q

Why does an action potential propagate in one
direction along the axon?

A

Refractory period prevents backpropagation of action potential

31
Q

Since action potentials are all-or-none, how are
differences in the signal intensity conveyed?

A

Firing frequency and pattern of action potentials

32
Q

Conduction velocity is defined by:
- ____diameter
- density of ___ channels
- myelin ____
-distance between _____

A

Axon
Na+
Insulation
Nodes of ranvier

33
Q

__________ means that action potentials jump from one node of ranvier to the next thus propagating much faster

A

Saltatory conduction

34
Q

Action potentials jumping from one node of ranvier to the next is due to ________

A

Myelination of the axon

35
Q

Nodes of ranvier are bare part of the ____ that support action potential conduction

A

Axon

36
Q

Glial cells provide ___

A

Myelin

37
Q

___ is cellular process of glial cells

A

Myelin

38
Q

Myelin is consisted of tightly wrapped cell __

A

Membrane

39
Q

Lipid bilayer does not pass ___

A

Ions

40
Q

___ is mostly cell membrane = good insulation

A

Myelin

41
Q

Electrical current propagates faster and farther along the _____ axon

A

Myelinated

42
Q

Myelin does/does not conduct current ?

A

Not

43
Q

Myelin is/is not part of the axon ?

A

Not

44
Q

__ axons conduct faster

A

Thicker

45
Q

__ nerve fibers:
- Proprioception
- contraction of skeletal muscle

A

Aα

46
Q

___ nerve fibers
-touch

A

A(beta)

47
Q

___nerve fibers
-acute pain

A

Aδ

48
Q

____ nerve fibers
- chronic or dull pain
- temperature
-itch

A

C

49
Q

Heavily _____ axons conduct faster

A

Myelinated

50
Q

What factors determine the action potential velocity?

A

– Axon diameter, myelination, Na+ channel density

51
Q

What is the role of nodes of Ranvier?

A

– Regeneration and propagation of action potential

52
Q

What type of cells provide myelin?

A

– CNS: oligodendrocytes, PNS: Schwann cells

53
Q

Action potential:
Intensity of signal is conveyed by ___

A

Frequency

54
Q

Action potential:
______ in one direction
– Initiated at ____ (highest density of Na channels)
– _____ channel distributed along the axon supports action potential propagation
(action potential is regenerated by Na channels)
– _______ prevents action potential from going backwards

A

Propagates
Axon hillock
Na+
Refractory period

55
Q

Conduction velocity (speed of propagation ) depends on:
– ____
–_____

A

Axon diameter
Myelination

Med310A (29 decks)

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