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Electrophysiology > Electrophysio intro > Flashcards

Electrophysio intro Flashcards

1
Q

Aka “steady potential”, “resting electrical activity” and “transmembrane potential”

A

RESTING MEMBRANE POTENTIAL:

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2
Q

The resting membrane potential of a small nerve is recorded at approximately___; ___ in a bigger nerve same with muscle tissues.

A

-70mV, -90mV

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3
Q

Can cause minimal depolarization in a cell but not enough to cause an action potential

A

SUBTHRESHOLD POTENTIAL:

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4
Q

THRESHOLD POTENTIAL/VOLTAGE:

A

Lowest effective electrical activity (intensity) to generate an action potential
o Aka CRITICAL FIRING LEVEL

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5
Q

An electrogenic pump – generating electrical activities in the cell since it is transporting ions in unequal amounts

PISO (Potassium- In; Sodium-Out);

A

Na-K pump

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6
Q

A resting cell is not really resting d/t the continuous activity of the Na- K pump; so the correct term to use is —

A

polarized cell

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7
Q

Allows Na to move in and K to move out following its concentration gradient using passive transport; 100x more permeable to K than Na ions; Ions are carried by the antiporters- together with Na-K leak channels are active when the cell is resting.

A

Na-K leak channels:

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8
Q

equation to use when measuring electrical activity of the cell

A

Nernst eqn

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9
Q

Concerned with all of the ions that affects the negativity of the membrane potential

A

Goldmann’s equation

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10
Q

Na voltage gated ion channel: how many gates?

A

2 (activation and inactivation)

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11
Q

Is generated when the cell is given and effective stimulation
o Effects in the muscle: contraction
o Effects in a nerve: transmission of impulses

A

Action potential

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12
Q

Action potential, what stage?

Opening of the activation gate of the voltage gated Na channels
 When the cell is stimulated almost all of the available Na channels are opened so that Na can move inward causing reversal of polarity
 Allows massive influx of Na making the inside of the cell more positive

A

Depolarization/Hypopolarization (hypo kasi you are getting nearer to 0mV so the membrane is becoming less polarized)

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13
Q

Closure of the Na inactivation gate will cause an automatic opening of the voltage gated K channel- activation gate
o Which will cause the cell to go back to a negative environment
o Rapid return to negativity
 Before reaching the (N) resting membrane potential the activation gate of the voltage gated Na channel will close, and will cause immediately opening of the inactivation gate
o To prepare the cell for another stimulation

A

Repolarization

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14
Q

what happens during hyperpolarization?

A

 Due to the slowly closing K channels
o There is no immediate closure of K channels which will provide more efflux of K making the inside of the cell more negative until it reaches the equilibrium potential for K ions; which will cause closure of voltage gated K channels
 Will try to maintain the RMP via the increase function of the Na-K pump

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15
Q

Many sodium channels are inactive and will not open, no matter what voltage is applied to the membrane. Most potassium channels are open.

The neuron cannot generate an action potential because sodium cannot move in through inactive channels and because potassium continues to move out through open voltage-gated channels.

A

Absolute refractory period

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16
Q

Immediately after the absolute refractory period, the cell can generate an action
potential, but only if it is depolarized to a value more positive than normal threshold

A

Relative refractory period

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17
Q
  1. The resting membrane potential is due mainly to the movement of potassium ions across the membrane because:

A. the concentration and electrical gradient of the Na+K+ATPase pump for the 3 of Na+ ions out of the cell

B. only 2 K+ ions are pumped in by the Na+K+- ATPase pump for 3 of Na+ions out of the cells

C. during resting conditions, K+ is in equilibrium

D. K+ has the largest resting conductance

A

D

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18
Q
  1. Which of the following effects of the action of Na+- K+-ATPase pump contributes the most to the generation of the resting membrane potential?

A. Maintenance of electrochemical gradient of Na+ ions and K+ ions across the membrane

B. Asymmetric distribution of diffusable permeant ions in the presence of a non-diffusable ion

C. electrogenic effect of pumping 3 Na ions out of the membrane and 2 K+ ions into the cell

D. Hydrolysis of ATP to ADP to produce conformational change of the Na+K_ ATPase pump

A

A

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19
Q
  1. The resting membrane potential differs from the equilibirium potential of potassium because:

A. the Na+K+AtPase pump counteracts passive fluxes of sodium and potassium ions

B. The ratio of open potassium leak channels to sodium channels is very high

C. The large non-diffusable anions are present in the interior of the cell.

D. The membrane is permeable to ions other than potassium

A

D

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20
Q

he sodium-potassium pump functions to pump
A) sodium ions out of the cell and potassium ions into the cell.
B) sodium ions into the cell and potassium ions out of the cell.
C) sodium and potassium ions into the cell.
D) sodium and potassium ions out of the cell.
E) sodium and potassium ions in both directions across the cell membrane.

A

A

21
Q 
What is the source of energy used to power the sodium-potassium pump?
	A)	breakdown of ATP
	B)	formation of ATP
	C)	transport of ATP by the pump
	D)	breakdown of GTP
	E)	transport of GTP by the pump
A

A

22
Q 
During one cycle, the sodium-potassium pump binds and moves.
	A)	1 Na+ and 2 K+.
	B)	2 Na+ and 2 K+.
	C)	2 Na+ and 3 K+.
	D)	3 Na+ and 2 K+.
	E)	3 Na+ and 3 K+.
A

D

23
Q

The sodium-potassium pump is a trans-membrane protein.
A) True
B) False

A

A

24
Q

The binding and release of sodium or potassium ions are due to conformational changes in the protein.
A) True
B) False

A

A

25
Q

The permeability of a cell for ions depends on the ______ in the cell membrane.

A

number and type of ion channels

26
Q

electrical and chemical forces ; causes the movement of that ion across the cell membrane

A

electrochemical gradient

27
Q

In —, the membrane potential depends only on potassium. Potassium comes to equilibrium when the membrane potential for the cell is -90 millivolts.

A

simple, non-excitable cells

28
Q

The resting membrane potential in neurons depends on the distribution of __ as well as potassium across the cell membrane. .

A

sodium, potassium

29
Q

Resting membrane potentials in neurons are commonly around –

A

-70 millivolts

30
Q

The – is essential for maintaining the resting membrane potential in neurons.

A

sodium-potassium pump

31
Q

In excitable cells, the __results from a rapid change in the permeability of the neuronal membrane to sodium and potassium. The permeability changes as voltage-gated ion channels open and close.

A

action potential

32
Q

The action potential is generated at the axon hillock, where the density of — channels is greatest.

A

voltage-gated sodium

33
Q

Weak stimuli that do not reach threshold do not produce an action potential. Thus we say that the action potential is an – event.

A

all-or- none

34
Q

T or F: Action potentials always have the same amplitude and the same duration.

A

T

35
Q

what stage: Voltage-gated sodium channels continue to inactivate, then reset to the closed state. Potassium channels continue to open. This results in a net movement of positive charge out of the cell, repolarizing the cell.

A

Repolarization

36
Q
  1. All of the following are TRUE of voltage-gated sodium ion channels EXCEPT:
    a. They assume a closed inactivatable state before the membrane reaches the equilibrium potential for sodium
    b. closure of their inactivation gate causes absolute refractory period
    c. They are opened when the membrane is hyperpolarized
    d. They are virtually closed when the cell is at rest
A

C

37
Q
  1. All of the following contribute to the downward slope of the spike potential of an action potential
    EXCEPT:

a. voltage-gated potassium channels
b. voltage-gated sodium channels
c. potassium leak channels
d. Na+-K+-ATPase pump

A

B

Voltage-gated sodium channels allow the influx of sodium when the channels are excited and change conformation, thus leading to an initial sharp rise of the spike potential.

38
Q
  1. In which of the following components of the action potential is conductance through voltage-gated potassium channels NOT contributory to the decreased membrane excitability?
    a. Upward spike of spike potential
    b. Relative refractory period
    c. After-hyperpolarization
    d. All of the above
A

B

39
Q

An action potential…
A) causes the neuron cell membrane to become unable to alter its charge.
B) causes the outside of the neuron cell membrane to become positively charged in reference to the inside.
C) causes the inside of the neuron cell membrane to become positively charged in reference to the outside.
D) causes the inside of the neuron cell membrane to become negatively charged in reference to the outside.
E) causes the inside of the neuron cell membrane to become neutrally charged in reference to the outside.

A

C

40
Q 
An action potential generates local currents that tend to \_\_\_\_\_ the membrane immediately adjacent to the action potential.
	A)	depolarize
	B)	repolarize
	C)	hyperpolarize
	D)	stabilize
	E)	neutralize
A

A

41
Q

Absolute refractory period causes…
A) action potential propagation to cease
B) action potential propagation to begin
C) action potential propagation to increase
D) action potential propagation to occur in both directions
E) action potential propagation to occur in one direction

A

E

42
Q

Action potentials can travel in both directions on the axon.
A) True
B) False

A

B

43
Q

Threshold is the minimum current required for the cell membrane to generate an action potential.
A) True
B) False

A

A

44
Q

Depolarization occurs because…
A) potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
B) the extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
C) the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
D) more sodium ions diffuse into the cell than potassium ions diffuse out of it.
E) the inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases.

A

D

45
Q

Repolarization occurs because…
A) potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
B) the extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
C) the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
D) more sodium ions diffuse into the cell than potassium ions diffuse out of it.
E) the inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases.

A

A

46
Q

Hyperpolarization, or afterpotential occurs because…
A) potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close.
B) the extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value.
C) the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
D) more sodium ions diffuse into the cell than potassium ions diffuse out of it.
E) the inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases

A

C

47
Q

After the passage of the action potential, the sodium-potassium pump reestablishes the resting membrane potential.
A) True
B) False

A

A

48
Q

The sodium-potassium pump uses bulk transport to move the sodium and potassium ions.
A) True
B) False

A

B

Electrophysiology (3 decks)

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