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physiology test 3 > generating an action potential > Flashcards

generating an action potential Flashcards

1
Q

the fluid on either side of the cell membrane differ in charge because?

A

of their basic ionic compositions

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2
Q

A natural affinity exists between anions and ______

A

cation

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3
Q

anions are defined as?

A

negatively charged ions

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4
Q

cations are defined as?

A

poisitvely charged ions

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5
Q

Charges that are positives and positive will _____ each other

A

repel because like electrical charges repel each other

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6
Q

charges that are positive and negatively charged will ______ each other.

A

attract

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7
Q

Sodium is a _______ ion

A

positive

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8
Q

Chloride ions are negative or positive?

A

negative

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9
Q

sodium and chloride will ______ each other?

A

attract each other because the sodium is positively charged and the chloride is negatively charged.

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10
Q

potassium is negative or positively charged?

A

positively charged

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11
Q

Sodium and potassium will ______ each other.

A

repel each other because they are both positively charged, and like charged ions repel one another

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12
Q

What two ions have a high concentration outside the cell?

A

sodium and chloride

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13
Q

What two things are highly concentrated inside the cell?

A

potassium and other negatively charged protein molecules

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14
Q

Define resting membrane potential?

A

The difference in electrical charge between the intracellular state and the extracellular state of an unstimulated neuron.

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15
Q

the extracellular state of a neuron is _______ charged.

A

positively

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16
Q

the intracellular state of a neuron is ______ charged.

A

negatively

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17
Q

the difference between the intracellular and extracellular sides of a neuron is approximately _____ millivolts.

A

70

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18
Q

the interior fluid is of the cell is approximately _____ _____ millivolts relative to the fluid outside of the cell.

A

minus 70

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19
Q

the cell membrane that has a resting membrane potential of 70 millivolts, at rest is ______ and holds the potential to _____

A

polarized

change

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20
Q

the most extremem change from the cell’s resting potential is called?

A

the action potential

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21
Q

describe action potential?

A

a quick combination of chemical and electrical activity inside and outside of the cell that actually reverses the polarity of the axon cell membrane, the intracellular fluid becomes more positive charge relative to the extracellular fluid after an action potential has occured.

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22
Q

how long does an action potential last?

A

1 millisecond

23
Q

because ions carry an electrical charge. The term _____ _____ describe the difference in electrical charge between barriers.

A

voltage gradient

24
Q

what two process operate to maintain the resting potential to set the stage for the action potential?

A

electrostatic pressure

diffusion

25
Q

define electrostatic pressure

A

the force exerted by the attraction or repulsion of electrical charges

26
Q

describe how diffusion is prevented in the resting potential

A

the cellular barrier prevents the cations and anions to evenly distribute between intracellular and extracellular.

27
Q

ion channels in the phospholipid bilayer of the cellular membrane are closed to _____ when the neuron is at resting potential?

A

sodium

28
Q

the neuron has a threshold potential which means what?

A

any stimulation below the threshold potential results in little or no change in the membrane potential.

29
Q

what are graded potentials?

A

ultralocalized voltage changes that increase or decrease membrane voltage

30
Q

hyperpolarizations results from what?

A

when the extracellular fluid becomes more positive because of either an efflux of potassium or an influx of cloride ions.

31
Q

hyperpolarization ______ the membrane voltage, make the membrane more _____ charged.

A

increases

negatively

32
Q

depolarization in an action potential results form what?

A

an influx of sodium ions, decreasing the membrane voltage and making the membrane more positively charged.

33
Q

What is the source that fuels the sodium/potassium pump

A

the pump uses most of the ATP that the neuron produces

34
Q

Describe the function of the Na/K pump affecting the cell membrane

A

This pump comes into play when the K+ pumps continue to dump too much potassium out of the cell causing Hyperpolarisation (-90, the cell is more negative). This pump activates to regain a resting potential for the cell, inforcing the cell to have only 2 K+ intracellularly and 3Na+ extracellularly.

35
Q

describe a subthreshold stimulus?

A

a stimulus that results in some ion channels opening and raising the membrane potential some but not to the threshold and results in no effect is observed.

36
Q

If a stimulus exceeds the threshold for excitation, what happens?

A

the sodium channels open up and the neuron fires with everything the membrane has reaching +30 mV

37
Q

A neuron must return to its ______ in order to carry out another action potential

A

resting potential

38
Q

At what rate do neurons fire at?

A

500 HTZ or 500 times per second

39
Q

How long does each action potential take to occur

A

2 milliseconds including the refractory period

40
Q

after an action potential takes place, potassium channels are _____ which leads to a neuron approaching what type of state

A

OPEN

resting membrane potential

41
Q

During repolarization, what pressure are operating on potassium movement

A

electrostatic and diffusion pressures

42
Q

Once potassium chanels reach a resting state of ___, what mechanism of action occurs next

A

-70

Potassium channels slowly close allowing slow leakage of potassium to continue, this leads to hyperpolarization

43
Q

During hyperpolarization, what type of charge takes place

A

an even greater negative charge relative to the extracellular space

(K is + and is continuing to move outside of the cell)

44
Q

as potassium continue to shift out of the neuron, it accumilates around the _____

A

Cell membrane

45
Q

In hyperpolarization, potassium accumilated around the cell membrane making it have a ____ charge, until the potassium diffuses away from what mechanism?

A

Positive

this happens by diffusion and electrostatic pressure along with potassium harvesting

46
Q

once the membrane potential reaches ________, a second set of voltage gated channels open, releasing potassium out of the neuron.

this is known as?

A

+30

potassium efflux

47
Q

when do potassium voltage gated channels open?

A

when membrane potential reaches +30

48
Q

when does sodium channels close?

A

membrane potential reaches +30

49
Q

describe what takes place during absolute refractory period

A

From threshold to threshold (-55 to -70) causing a total inability for the neuron to respond to any charge/impulse

50
Q

potassium efflux is accelerated by what two forces?

A

electrostatic pressure and diffusion

51
Q

as potassium efflux occurs during _______, the membrane potential becomes more negative.

A

Repolarization

52
Q

membrane potential is first reached following depolarization in about ____ millisecond, however, further potassium will leak out called ________

A

1

hyperpolarization

53
Q

what occurs during relative refractory period

A

occurs after repolarisation threshold is met (-70) and takes place until resting potential is reached. During this time, the neuron may respond to more insistent depolarizing signals

54
Q

What uses the majority fo the ATP the neuron produces?

A

the Na-Potassium Pump

physiology test 3 (11 decks)

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