Week 2 Regional Anesthesia & LA's 1 of 4

Question 1

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

Answer 1

Depolarization

Question 2

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

Answer 2

Repolarization

Question 3

Repolarization results from the movement of positively charged potassium ions out

Answer 3

of the cells

Question 4

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:

Answer 4

action potential

Question 5

Action potential have stereotypical

Answer 5

size and shape

Question 6

Action potential are propagating and are

Answer 6

all or none

Question 7

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

Answer 7

threshold

Question 8

At threshold potential, net inward current becomes larger than

Answer 8

net outward current

Question 9

The resulting depolarization becomes self-sustaining and gives rise to

Answer 9

upstroke of AP

Question 10

If net inward current is less than net outward current

Answer 10

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

Question 11

AP sequence

Initial segments of the axon

Answer 11

depolarizes

Question 12

AP Sequence

When depolarization reaches threshold

Answer 12

• 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”

Question 13

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

Answer 13

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)

Question 14

The AP causes the segment of the nerve to:

Answer 14

depolarize to threshold

Question 15

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

Answer 15

it reaches the nerve terminal

Question 16

The AP triggers the release of chemicals from

Answer 16

nerve terminal

Question 17

Nerve AP lasts

Answer 17

1 ms (one thousandth of a second)

Question 18

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

Answer 18

the AXON

Question 19

The axon is where

Answer 19

voltage gated na-channels are located in neurons

Question 20

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

Answer 20

closed

Question 21

Activation of K channels starts what:

Answer 21

repolarization

Question 22

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

Answer 22

1 (one)

Question 23

K channels will open when Na gates are

Answer 23

closed.

Question 24

phase 1 AP

Answer 24

Na channels open

Na begins to enter cell

Question 25

Phase 2 AP

Answer 25

K channels open

K begins to leave cell

Question 26

Phase 3 AP

Answer 26

Na channels become refractory

no more Na enters cell

Question 27

Phase 4 AP

Answer 27

K continues to leave cell

Causes membrane potential to return to resting level

Question 28

Phase 5 AP

Answer 28

K channel closes

Na channels reset

Question 29

Phase 6 AP

Answer 29

Extra K outside diffuses away

Question 30

Cells contain high ___ concentrations

Answer 30

potassium

Question 31

cells have membranes that are essentially permeable to K+ at

Answer 31

at rest

Question 32

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

Answer 32

Membrane Potential

membrane electrical potential difference

Question 33

Membrane Potential is measure in

Answer 33

mV

Question 34

Typically resting membrane potentials in neurons are

Answer 34

-70 to -90 mV

Question 35

During the UPSTROKE of an AP:

-Na permeability increases due to

Answer 35

opening of Na channels

inward movement of Na

Question 36

During the DOWNSTROKE of an AP:

Na permeability decreases due to

Answer 36

inactivation of Na channels

Question 37

During the DOWNSTROKE of an AP:

K permeability increases due to

Answer 37

Opening of K channels

outward movement of K

Question 38

After HYPERPOLARIZATION of membrane following an AP:

There is

Answer 38

increased K conductance

due to delayed closure of K channels

Question 39

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

Answer 39

resting membrane potential

Question 40

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

Answer 40

K+ > Na+

Question 41

Na/K pump maintains

Answer 41

resting membrane potential

3Na OUT and 2K in

Question 42

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

Answer 42

Action Potential

Question 43

Interior becomes less negative

Answer 43

rapid depolarization

Question 44

Excitable cells are

Answer 44

nerves

muscles

Question 45

Depolarization

Answer 45

Upstroke of the AP

-Inward Na movement

Question 46

Lidocaine blocks these

Answer 46

voltage sensitive Na-channels

-and abolish AP

Question 47

Repolarization

Answer 47

Downstroke of AP

-outward K movement

Question 48

Hyperpolarizing the membrane potential is a result of

Answer 48

outward flow of K

Question 49

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

Answer 49

Absolute refractory period

Question 50

Absolute refractory Period is due to closure of

Answer 50

inactivation Na gates

Question 51

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

Answer 51

Relative refractory period

Question 52

Purpose of refractory period

Answer 52

to protect the cell from over excitation

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

Question 53

Name 4 Properties of AP:

Answer 53

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