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anatomy and physiology lecture > Membrane potential > Flashcards

Membrane potential Flashcards

1
Q

2 ways membrane potentials can develop

A

active transport and diffusion

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2
Q

Describe how the sodium-potassium exchange pump works

A

The sodium-potassium pump system moves sodium and potassium ions against large concentration gradients. It moves two potassium ions into the cell where potassium levels are high, and pumps three sodium ions out of the cell and into the extracellular fluid.

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3
Q

How many sodium ions are
transported and in which direction? How many potassium ions are transported and in which direction?

A

In each cycle, three sodium ions exit the cell, while two potassium ions enter.

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4
Q

Does it move against a concentration gradient

A

The sodium and potassium move against the concentration gradients

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5
Q

What are cations?

A

Cations are ions that are positively charged

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6
Q

anions

A

ions that are negatively charged

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7
Q

What are examples of anions found just inside of the cell membrane? Do they typically move out of the cell or stay put?

A

organic phosphates, sulfates, protein anions *typically stay put

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8
Q

In which direction would the sodium ions diffuse, if they could diffuse?

A

out

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9
Q

In which direction would the potassium ions diffuse, if they could diffuse?

A

in

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10
Q

Nernst potential

A

the ratio of the tendency for ions to diffuse in one direction versus another

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11
Q

what is the nernst potential of sodium ions in our cell membrane example

A

+61mV

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12
Q

what is the nernst potential of potassium ions in our cell membrane example?

A

-94mV

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13
Q

The original development of the membrane potential is by

A

active transport

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14
Q

n the resting cell membrane, immediately inside of the cell membrane are more _________ charges than ____________ charges

A

negative; positive

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15
Q

A negative membrane potential may be re-established by

A

diffusion

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16
Q

What is an action potential

A

Action potentials (those electrical impulses that send signals around your body) are nothing more than a temporary shift (from negative to positive) in the neuron’s membrane potential caused by ions suddenly flowing in and out of the neuron.

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17
Q

Name 3 ways in which an action potential may be elicited in a nerve fiber?

A

electric stimulation, mechanical compression, application of chemicals to the membrane

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18
Q

The action potential occurs when the membrane becomes more permeable to _____________ ions. These will diffuse in which direction, into or out of the cell?

A

sodium; out

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19
Q

what is depolarization

A

movement of a cell’s membrane potential to a more positive value (i.e. movement closer to zero from resting membrane potential). When a neuron is depolarized, it is more likely to fire an action potential.

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20
Q

What channels open in depolarization

A

Na+

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21
Q

What channels are closed in depolarization

A

K+

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22
Q

What happens to the membrane potential in depolarization

A

it reverses and goes above zero

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23
Q

What ions are moving during depolarization and in what direction

A

Na+ ions in

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24
Q

Is nernst potential achieved during depolarization

A

no

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25
Q

What is the reversal potential

A

the positive potential that develops momentarily inside the fiber

26
Q

Define repolarization

A

the excessive + charges inside the fiber are transferred back out of the fiber & normal - resting membrane potential returns

27
Q

what causes repolarization

A

by the closing of sodium ion channels and the opening of potassium ion channels.

28
Q

What channels are open in repolarization

A

K+

29
Q

What channels close during repolarization

A

Na+

30
Q

what happens to the membrane potential during repolarization

A

re-established

31
Q

what ions are moving and in what direction duing repolarization

A

K+ out

32
Q

Is nernst potential achieved in repolarization

A

yes

33
Q

are there more sodium ions inside the cell or outside at the end of repolarization

A

in

34
Q

are there more potassium ions inside the cell or outside at the end of repolarization

A

out

35
Q

did the membrane potential just become re-established after repolarization

A

yes

36
Q

what are 2 different types of channels

A

Na+ and K+

37
Q

at rest, sodium channels are almost completely

A

closed

38
Q

at rest, potassium channels are

A

partially open

39
Q

after potential

A

brief hyperpolarization period following the action potential

40
Q

Is after potential hyperpolarized or hypopolarized

A

hyperpolarized

41
Q

what causes the after potential

A

the efflux of K+

42
Q

did this ion reach its nernst potential during after potential

A

yes

43
Q

absolute refractory period

A

period of time of complete insensitivity to another stimulus

44
Q

can a greater-than-threshold strength stimulus initiate another action potential

A

no because it cant respond unless ready (flushing toilet)

45
Q

relative refractory period

A

near end of repolarization phase

46
Q

can a greater-than-threshold strength stimulus initiate another action potential

A

Yes, because it is below resting membrane potential

47
Q

In what direction do action potentials travel

A

all directions

48
Q

what is the all or none principle

A

strength by which nerve/muscle responds to stimulus

49
Q

what is a subthreshold stimulus

A

stimulus to small to produce action potential

50
Q

what are graded or local potentials?

A

short lived local changes in membrane potential

51
Q

Can graded or local potentials spread far from the area surrounding the site of stimulation

A

no

52
Q

can graded or local potentials summate

A

no

53
Q

what is a threshold stimulus

A

minimum stimulus needed to achieve action potential

54
Q

does a greater-than-threshold stimulus result in an action potential with greater amplitude

A

no

55
Q

If the stimulus strength increases, then action potential frequency will

A

increase

56
Q

Epsp

A

excitatory postsynaptic potential

57
Q

Ipsp

A

inhibitory postsynaptic potential

58
Q

What usually results in Na+ gate opening

A

epsp

59
Q

what usually results in K+ gate opening

A

ipsp

60
Q

If the membrane becomes hypopolarized, does this increase or decrease the chance that summation may result in an action potential

A

increase

61
Q

if the membrane becomes hyperpolarized does this increase or decrease the chance that summation may result in an action potential

A

decrease

anatomy and physiology lecture (3 decks)

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