Week 2 Regional Anesthesia & LA's 1 of 4 Flashcards

1
Q

Makes the cell membrane potential less negative due to movement of positively charged sodium ions into the cell is called:

A

Depolarization

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2
Q

Change after depolarization, that returns the membrane potential back to resting potential is known as:

A

Repolarization

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3
Q

Repolarization results from the movement of positively charged potassium ions out

A

of the cells

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4
Q

Is a property of excitable cells (nerve and muscle) that consists of a rapid depolarization, or upstroke, followed by repolarization of the membrane potential. this is:

A

action potential

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5
Q

Action potential have stereotypical

A

size and shape

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6
Q

Action potential are propagating and are

A

all or none

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7
Q

Is the membrane potential at which the action potential is inevitable is known as

A

threshold

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8
Q

At threshold potential, net inward current becomes larger than

A

net outward current

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9
Q

The resulting depolarization becomes self-sustaining and gives rise to

A

upstroke of AP

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10
Q

If net inward current is less than net outward current

A

no AP will occur (i.e. all or none response)

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11
Q

AP sequence

Initial segments of the axon

A

depolarizes

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12
Q

AP Sequence

When depolarization reaches threshold

A
  • Na channels open
  • Na rushes inward down concentration gradient (depolarization occurs)
  • the inside of the cell momentarily becomes positively charged (with respect to the outside of the cell which is negative)
  • Na channels Shut (inactivated state)
  • K channels Open
  • K rushes out of the cell causing electronegativity to be restored to resting level (repolarization / restoration of the membrane potential to resting level)
  • when membrane repolarizes, Na channels return to original configuration (closed) and in the “activated state”
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13
Q

After the AP has passed, what restores the Na/K ionic balance again?

A

the Na/K pump

  • after AP has passed, the Na/K pump extrudes the Na that has entered the cell and recaptures the K that has left the cell (reinstating balance of Na/K ionic balance)
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14
Q

The AP causes the segment of the nerve to:

A

depolarize to threshold

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15
Q

The AP is “self propagating” and does not stop until

A

it reaches the nerve terminal

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16
Q

The AP triggers the release of chemicals from

A

nerve terminal

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17
Q

Nerve AP lasts

A

1 ms (one thousandth of a second)

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18
Q

In the neuron, voltage-gated sodium channels are found principally in:

A

the AXON

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19
Q

The axon is where

A

voltage gated na-channels are located in neurons

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20
Q

At rest, the K-gates are open/closed?

A

closed

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21
Q

Activation of K channels starts what:

A

repolarization

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22
Q

How many k- gates are on the inside of membrane?

23
Q

K channels will open when Na gates are

24
Q

phase 1 AP

A

Na channels open

Na begins to enter cell

25
Phase 2 AP
K channels open | K begins to leave cell
26
Phase 3 AP
Na channels become refractory | no more Na enters cell
27
Phase 4 AP
K continues to leave cell | Causes membrane potential to return to resting level
28
Phase 5 AP
K channel closes | Na channels reset
29
Phase 6 AP
Extra K outside diffuses away
30
Cells contain high ___ concentrations
potassium
31
cells have membranes that are essentially permeable to K+ at
at rest
32
what is generated by diffusion of K+ ions and charge separation
Membrane Potential | membrane electrical potential difference
33
Membrane Potential is measure in
mV
34
Typically resting membrane potentials in neurons are
-70 to -90 mV
35
During the UPSTROKE of an AP: -Na permeability increases due to
opening of Na channels | inward movement of Na
36
During the DOWNSTROKE of an AP: Na permeability decreases due to
inactivation of Na channels
37
During the DOWNSTROKE of an AP: K permeability increases due to
Opening of K channels | outward movement of K
38
After HYPERPOLARIZATION of membrane following an AP: There is
increased K conductance | due to delayed closure of K channels
39
The measured potential difference across the cell membrane in mV is known as:
resting membrane potential
40
At rest, the nerve membrane is more permeable to ___ than to ____.
K+ > Na+
41
Na/K pump maintains
resting membrane potential | 3Na OUT and 2K in
42
a property of excitable cells (nerve, muscles) that consist of a rapid depolarization followed by repolarization of membrane potential is:
Action Potential
43
Interior becomes less negative
rapid depolarization
44
Excitable cells are
nerves | muscles
45
Depolarization
Upstroke of the AP | -Inward Na movement
46
Lidocaine blocks these
voltage sensitive Na-channels -and abolish AP
47
Repolarization
Downstroke of AP | -outward K movement
48
Hyperpolarizing the membrane potential is a result of
outward flow of K
49
A period during which another AP cannot be elicited no matter how large the stimulus is called:
Absolute refractory period
50
Absolute refractory Period is due to closure of
inactivation Na gates
51
A period during which an AP can be elicited only if a larger than usual stimulus is provided is called:
Relative refractory period
52
Purpose of refractory period
to protect the cell from over excitation | allow for a recovery period b/w the AP's
53
Name 4 Properties of AP:
1. constant size and shape 2. Propagation 3. All or none Law 4. Threshold is the membrane potential at which the AP is inevitable