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

SUM'20 - Regional > Week 2 Regional Anesthesia & LA's 1 of 4 > Flashcards

Flashcards in Week 2 Regional Anesthesia & LA's 1 of 4 Deck (53)
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1
Q

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

A

Depolarization

2
Q

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

A

Repolarization

3
Q

Repolarization results from the movement of positively charged potassium ions out

A

of the cells

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

5
Q

Action potential have stereotypical

A

size and shape

6
Q

Action potential are propagating and are

A

all or none

7
Q

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

A

threshold

8
Q

At threshold potential, net inward current becomes larger than

A

net outward current

9
Q

The resulting depolarization becomes self-sustaining and gives rise to

A

upstroke of AP

10
Q

If net inward current is less than net outward current

A

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

11
Q

AP sequence

Initial segments of the axon

A

depolarizes

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”
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)
14
Q

The AP causes the segment of the nerve to:

A

depolarize to threshold

15
Q

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

A

it reaches the nerve terminal

16
Q

The AP triggers the release of chemicals from

A

nerve terminal

17
Q

Nerve AP lasts

A

1 ms (one thousandth of a second)

18
Q

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

A

the AXON

19
Q

The axon is where

A

voltage gated na-channels are located in neurons

20
Q

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

A

closed

21
Q

Activation of K channels starts what:

A

repolarization

22
Q

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

A

1 (one)

23
Q

K channels will open when Na gates are

A

closed.

24
Q

phase 1 AP

A

Na channels open

Na begins to enter cell

25
Q

Phase 2 AP

A

K channels open

K begins to leave cell

26
Q

Phase 3 AP

A

Na channels become refractory

no more Na enters cell

27
Q

Phase 4 AP

A

K continues to leave cell

Causes membrane potential to return to resting level

28
Q

Phase 5 AP

A

K channel closes

Na channels reset

29
Q

Phase 6 AP

A

Extra K outside diffuses away

30
Q

Cells contain high ___ concentrations

A

potassium

31
Q

cells have membranes that are essentially permeable to K+ at

A

at rest

32
Q

what is generated by diffusion of K+ ions and charge separation

A

Membrane Potential

membrane electrical potential difference

33
Q

Membrane Potential is measure in

A

mV

34
Q

Typically resting membrane potentials in neurons are

A

-70 to -90 mV

35
Q

During the UPSTROKE of an AP:

-Na permeability increases due to

A

opening of Na channels

inward movement of Na

36
Q

During the DOWNSTROKE of an AP:

Na permeability decreases due to

A

inactivation of Na channels

37
Q

During the DOWNSTROKE of an AP:

K permeability increases due to

A

Opening of K channels

outward movement of K

38
Q

After HYPERPOLARIZATION of membrane following an AP:

There is

A

increased K conductance

due to delayed closure of K channels

39
Q

The measured potential difference across the cell membrane in mV is known as:

A

resting membrane potential

40
Q

At rest, the nerve membrane is more permeable to ___ than to ____.

A

K+ > Na+

41
Q

Na/K pump maintains

A

resting membrane potential

3Na OUT and 2K in

42
Q

a property of excitable cells (nerve, muscles) that consist of a rapid depolarization followed by repolarization of membrane potential is:

A

Action Potential

43
Q

Interior becomes less negative

A

rapid depolarization

44
Q

Excitable cells are

A

nerves

muscles

45
Q

Depolarization

A

Upstroke of the AP

-Inward Na movement

46
Q

Lidocaine blocks these

A

voltage sensitive Na-channels

-and abolish AP

47
Q

Repolarization

A

Downstroke of AP

-outward K movement

48
Q

Hyperpolarizing the membrane potential is a result of

A

outward flow of K

49
Q

A period during which another AP cannot be elicited no matter how large the stimulus is called:

A

Absolute refractory period

50
Q

Absolute refractory Period is due to closure of

A

inactivation Na gates

51
Q

A period during which an AP can be elicited only if a larger than usual stimulus is provided is called:

A

Relative refractory period

52
Q

Purpose of refractory period

A

to protect the cell from over excitation

allow for a recovery period b/w the AP’s

53
Q

Name 4 Properties of AP:

A
  1. constant size and shape
  2. Propagation
  3. All or none Law
  4. Threshold is the membrane potential at which the AP is inevitable