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ANAP 500 > Membrane Potentials & Action Potentials > Flashcards

Membrane Potentials & Action Potentials Flashcards

1
Q

Electrical potential or electrical difference across (all) cell membrane

A

Membrane potential

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2
Q

What are some types of excitable cells that can generate electrical impulses (APs) and transmit them along the cell membrane?

A 
Nerve fibers
Skeletal muscle fibers
Cardiac muscle fibers
Smoothie muscle fibers
Cardiac electrical fibers
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3
Q

Electrical difference/gradient across the cell membrane in the resting state

A

Resting membrane potential

RMP

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4
Q

Cell membranes are polarized, meaning what about - and + charges?

A

Negative charges tend to accumulate on the inside of the cell membrane, positive charges tend to accumulate on the outside of the cell membrane

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5
Q

ALWAYS compare the ______ of the cell to the _______ of the cell.

A

Always compare the INSIDE of the cell to the OUTSIDE of the cell

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6
Q

Interpret a MP of -90mV

A

The INSIDE of the cell membrane if 90 mV more negative than the outside of the cell membrane

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7
Q

The electrical difference is just inside and just outside (RIGHT ON) the cell membrane. TRUE/FALSE

A

TRUE

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8
Q

Intracellular and extracellular fluids are electrically charged. TRUE/FALSE

A

FALSE

Intracellular/extracellular fluids are ELECTRICALLY NEUTRAL!

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9
Q

What are the 4 main contributors to the cell membrane in order from greatest–>least impact.

A

Potassium leak channels
Sodium leak channels
Sodium - potassium pump
Accumulation of negatively charges proteins along the inside of the cell membrane

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10
Q

What is the main contributor to membrane potential?

A

Potassium leak channels

Positive charges constantly moving out of the cell

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11
Q

If cell only had K+ leak channels active, what would RMP be?

A

-94mV

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12
Q

If only had K+ and Na+ leak channels, what would RMP be?

What is the change in mV from adding Na+ leak channels?

A

-86mV

8mV change

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13
Q

When K+ leak channels, Na+ leak channels, and Na-K pump are all present, what is the RMP?
What is the change in mV of RMP when adding pump to leak channels?

A

-90mV

4mV change

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14
Q

Transmission of electrical impulses along membranes of excitable cells is ?

A

Action Potential

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15
Q

What are the 4 main components of an action potential?

A

RMP
Threshold potential
Depolarization
Repolarization

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16
Q

An initial stimulus to a skeletal/muscle or nerve fiber does what to the cell and the MP?

A

Inward movement of sodium into the cell, raises the RMP in a less negative fashion

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17
Q

If RMP reaches TP, what type of channels are opened?

What happens to the MP?

A

Opening of voltage gated Na channels

Lots of + charges into cell bc FAST, MP increases quickly

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18
Q

What ends depolarization? This happens at ____ amplitude or overshoot.

A

Closure of voltage gates sodium channels

Peak amplitude

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19
Q

What happens at about the same time that voltage gated sodium channels close, and begins repolarization?

A

Voltage gated potassium channels are opened– + charges leaving the cell, brings RMP back down to -90mV

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20
Q

Action potentials are VERY FAST in skeletal muscle fibers and Nerve fibers. TRUE/FALSE?

A

TRUE

Occurs in ~0.3 milliseconds!

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21
Q

This allows for return to RMP and recovery of the cell membrane before another AP can occur

A

Refractory periods

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22
Q

What are the 3 refractory periods?

A

Absolute
Relative
Supernormal/vulnerable

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23
Q

During this period, the cell will NOT depolarize again regardless of how strong the stimulus is

A

Absolute refractory period

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24
Q

Requires and EXTRA STRONG stimulus to depolarize the cell again

A

Relative refractory period

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25
Q

Even a MILD stimulus may cause another depolarization during this period

A

Supernormal/vulnerable refractory period

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26
Q

This refractory period is from RMP, through depolarization, and almost through repolarization, until returns to TP.

A

Absolute refractory period

27
Q

The Relative refractory period begins @ _______ potential (-60mV) and ends at ~______ mV.

A

RRP Begins @ TP

Ends at -80 to -85mV

28
Q

If an extra strong stimulus occurs during RRP in the heart, what will we see on the ECG?

A

A QRS sitting directly on top of the T wave

Abnormal occurance

29
Q

This refractory period is from -80-85mV to -90mV. Only a mild stimulus will initiate an AP here

A

Supernormal/vulnerable refractory period

30
Q

What would result on our EKG if a mild stimulus occur EC in the SNP?

A

QRS sitting on the down stroke of the T wave

Not normal.

31
Q

Why is it easier to to initiate another AP in the SNP than the RRP?

A

SNP we are closer to TP than we are at RMP

The reason a lesser stimulus is needed in the SNP is because the voltage gated Na+ channels have not had time to reset themselves yet in the RRP

32
Q

What are the 3 types of stimuli that can initiate APs?

A

Chemical
Electrical
Mechanical

33
Q

What is an example of a chemical stimulus AP

A

Ach gates Na channel: binds to the Na channel, opens, influx of Na, RMP-TP; opening of v-g Na channels

34
Q

What is a good example of an electrical stimulus initiating AP

A

The heart and conduction system

35
Q

What is a good example of a mechanical stimulus initiating an AP?

A

Receptors in you skin that respond to pressure, touch, tickle, and itch, etc. Send AP up to the brain to interpret it.

36
Q

The initial stimulus must cause enough ______ for RMP to reach TP

A

Sodium influx

37
Q

If initial event foes not accuse RMP to reach TP then AP/depolarization will NOT occur. If initial even causes RMP to reach TP, then dep/AP WILL occur. This is described as the __________ phenomenon.

A

“All or none” phenomenon

38
Q

If it is a suprathreshold stimulus, then it will cause a GREATER amplitude of depolarization than just a normal threshold stimulus. TRUE/FALSE?

A

FALSE

It will not cause a greater amplitude of depolarization, once TP is reached, the AP occurs like normal. Same every time.

39
Q

The initial stimulus occurs at multiple points on the cell membrane. TRUE/FALSE?

A

FALSE.

Occurs at only ONE point on the cell membrane

40
Q

The AP occurs along the entire length of the cell membrane from initial point of stimulus bidirectionally. TRUE/FALSE?

A

TRUE

41
Q

Hyperkalemia causes ____polarization of the MP by doing what to the gradient?

A

Hyperkalemia = hypopolarization

Gradient is smaller and out flux of K is slower so MP is increased at a slower rate.

42
Q

Hypokalemia causes _______polarization of the cell.

A

Hypokalemia = hyperpolarization

43
Q

______polarization is inhibitory to APs.

A

Hyperpolarization

44
Q

Hypopolarization of RMP moves it CLOSER/FARTHER from TP?

A

RMP Moves CLOSER to TP when hypopolarized

45
Q

The closer RMP is to TP, the MORE voltage gated Na channels are activated. TRUE/FALSE?

A

FALSE.

The closer RMP to the TP , the LESS voltage gated Na channels are activated.

46
Q

If less v-g Na channels are opened, causes a __________ depolarization and _________ amplitude of depolarization

A

Slower depolarization

Decreased amplitude

47
Q

What does slow depolarization/decreased amplitude from hyperpolarization look like on the EKG?

A

PR interval gets longer
Can lose P wave
QRS will widen/flatten out
Asystole or VF

48
Q

In Hyperkalemia, the T wave represents repolarization, which is very _________ with _________ T waves.

A

Hyperkalemia; RAPED repolarization

TALL peaked T waves.

49
Q

In hypokalemia depolarization is relatively normal. Repolarization is slow and prolonged. TRUE/FALSE

A

TRUE

50
Q

Why is slow, prolonged depolarization in hypokalemia dangerous?

A

Ther is more opportunist for ectopic foci or electrical stimulus to cause an early depolarization

51
Q

When we talk about Potassium levels, we look at changes in RMP/TP?

A

RMP

52
Q

Extracellular concentrations of Ca regulate activity of what?

A

V-g Na channels

53
Q

Hypocalcemia moves TP ______ to RMP and it is EASIER/HARDER to open v-g sodium channels or initiate APs.

A

TP closer to RMP makes is EASIER to open v-g Na channels = AP’s

54
Q

In hypocalcemia, cells are very _________. Signs would be what in a physical assessment?

A

Excitable

Chvostek/trousseau

55
Q

In hypercalcemia, TP is moved CLOSER/FARTHER from RMP and it is EASIER/HARDER to open v-g Na channels.

A

Hypercalcemia TP FARTHER from RMP

Harder to open v-g Na channels and AP

56
Q

Signs of hypocalcemia in your patient?

A

Sleepy, in-somnolent, comatose, death

57
Q

Why are T waves peaked in hyperkalemia?

A

Up regulation of nicotinic receptors

58
Q

Upregulation of nicotinic receptors causes opening of sodium channels and depolarization and repolarization to occur, what happens during repolarization with K+?

A

Outflow of K+

59
Q

Succs increases K levels. What types of pts should you NOT give succs to?

A

Paralyzed
Burn
Crush injuries
Bedridden

60
Q

________ temporarily brings proper distance between RMP and TP during hyperkalemia

A

Calcium

61
Q

When treating hyperkalemia- bicarb, insulin, and hyperventilation all DECREASE/INCREASE pH so that H+ is released to DECREASE/INCREASE pH. This leads to shuttling K+ back into the cell to maintain electrical neutrality

A

Bicarb , insulin, and hyperventilation
Increase pH (alkalotic)
H+ decreases pH (more acidic)

62
Q

In hyperkalemia- Insulin and b2 agonist, albuterol, activate what that moves K= into the cell?

A

Na-K pump

63
Q

What are the only treatments that truly decrease total body potassium?

A

Dialysis

Kaexelate retention enema

ANAP 500 (6 decks)

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