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Physiology > Section 6 > Flashcards

Section 6 Flashcards

1
Q

The electrical potential difference between the inside and outside of the cell

A

Membrane potential or membrane voltage

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2
Q

Movement of an ionic current through the membrane

A

Ionic charge

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3
Q

Requires displacement of a positive charge off the cell membrane; no ion movement through the membrane

A

Capacitative charge

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4
Q

What are the two forces pushing ions through the plasma membrane?

A
  1. Diffusion force

2. Electromotive force

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5
Q

Particles that fit or carry a given charge pass through these channels freely; depends on size and/or concentration gradient

A

Open or intermittently opened channel

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6
Q

Changes in the membrane potential open and close the channel, important for action potential propagation/conduction

A

Voltage gated channel

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7
Q

Ligands attaching to protein open the channel; responsible for graded potentials

A

Ligand gated channels

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8
Q

Responsible for facilitated diffusion (carries specific molecules with its concentration gradient) and active transport

A

Membrane carrier protein channel

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9
Q

Membrane protein uses ATP energy to move specific molecules against their concentration gradient; oxygen dependent

A

Active transport

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10
Q

The plasma membrane is [hydrophilic/hydrophobic] on the outside and [hydrophilic/hydrophobic] on the inside.

A

Hydrophilic; hydrophobic

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11
Q

The net result of the separation of + and - charges is more [+/-] on the inside of the cell and more [+/-] on the outside of the cell.

A

-; +

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12
Q

Term used to describe the baseline voltage level of membrane polarization that exists in a cell at rest

A

Resting membrane potential

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13
Q

What is the average resting potential for motoneurons?

A

-70 mV

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14
Q

What is the average resting potential for muscle cells?

A

-90 mV

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15
Q

Name the four factors that cause the resting membrane potential

A
  1. Maintained charge separation by a semipermeable ion selective cell membrane
  2. K+ efflux - while leaving an organic anion (A-) inside the cell
  3. Cl- influx - while leaving Na+ outside the cell
  4. The Na+/K+ pump which prevents ions from distributing at equilibrium, thus maintaining charge separation
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16
Q

Rank the relative permeability of the membrane to charged particles from least to greatest.

A

A- < Na+ < Cl- < K+

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17
Q

The unequal membrane permeability and ion concentration allows more ____ diffusion out of the cell than ____ into the cell; this leads to the 2nd major cause of the resting membrane potential, ___ efflux leaving A- inside the cell.

A

K+; Na+; K+

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18
Q

True or False:

In a resting cell there is a higher concentration of K+ outside the cell and a higher concentration of Na+ inside the cell.

A

False; K+ is higher inside the cell and Na+ is higher outside the cell

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19
Q

What ions make the inside of the cell negatively charged?

A

A- left in the cell and Cl- moving in the cell (nerve cell only)

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20
Q

What ions make the outside of the cell positively charged?

A

K+ moves out and Na+ left out

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21
Q

True or False:

Na+ left behind because resting membrane’s permeability to Na+ is relatively low.

A

True

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22
Q

In a resting cell, the electromotive force tends to draw K+ [into/out of] the cell [against/with] its concentration gradient

A

Into; against

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23
Q

In a resting cell, the electromotive force tends to draw Na+ [into/out of] the cell [against/with] its concentration gradient

A

Into; with

24
Q

Since Na+ slowly leak into the cell over time, the Na+/ K+ pump actively pumps out _____ and pumps in _____

A

3 Na+ ions; 2 K+ ions

25
Q

The force that pushes an ion at the cell membrane from a region of greater concentration to a region of lesser concentration

A

Diffusion force

26
Q

The force that repels ions that have the same charge and attracts ions with opposite charges

A

Electromotive force (EMF)

27
Q

If an ion moves down its concentration gradient, would K+, Na+, and Cl- move into or out of the cell?

A
  1. K+ = out of
  2. Na+ = into
  3. Cl- = into
28
Q

If an ion moves with its EMF, would K+, Na+, and Cl- move into or out of the cell?

A
  1. K+ = into
  2. Na+ = into
  3. Cl- = out of
29
Q

When diffusion force and EMF action on the ion(s) are not equal, it results in

A

Ion movement

30
Q

The membrane potential/voltage at which the diffusion force is equal to the EMF is defined as ______.

A

Equilibrium potential

31
Q

No outward movement of K+ ions occurs when membrane potential = ____mV

A

-96

32
Q

No inward movement of Na+ ions occurs when membrane potential = ____mV

A

+66

33
Q

No inward movement of Cl- ions occurs when membrane potential = ____mV

A

-90

34
Q

K+ efflux causes the membrane potential to become more [positive/negative] with respect to the outside.

A

Negative

35
Q

Na+ influx causes the membrane potential to become more [positive/negative] with respect to the outside.

A

Positive

36
Q

Cl- influx causes the membrane potential to become more [positive/negative] with respect to the outside.

A

Negative

37
Q

The algebraic difference between the membrane potential and the ion’s equilibrium potential
(Driving Force = Em - Eion)

A

Driving Force

38
Q

Greater driving force = [greater/lesser] push on an ion

A

Greater

39
Q

True or False:

The polarity of the driving force is relative only to the ion in question.

A

True

40
Q

In a resting membrane, what is the net driving force for K+? Is it being driven in or out of the cell?

A

+6 mV; net outward force

[-90mV - (-96mV) = +6mV]

41
Q

In a resting membrane, what is the net driving force for Na+? Is it being driven in or out of the cell?

A

-156 mV; net large inward force

[-90mV - (+66mV) = -156mV]

42
Q

In a resting membrane, what is the net driving force for Cl- in a muscle cell? Is it being driven in or out of the cell?

A

0mV; no movement

[-90mV - (-90mV) = 0mV]

43
Q

In a resting membrane, what is the net driving force for Cl- in a nerve cell? Is it being driven in or out of the cell?

A

+20mV; net inward force

[-70mV - (-90mV) = +20mV]

44
Q

With ionic current, whether an ion moves thru a membrane depends on 2 things

A
  1. Driving force

2. Membrane permeability

45
Q

What ion has the greatest driving force at the resting membrane potential?

A

Na+

46
Q

During the upstroke of the action potential, the driving forces on both K+ and Cl- [increased/decreased] compared to resting condition.

A

Increased

47
Q

During the upstroke of the action potential, the driving forces on Na+ [increased/decreased] compared to resting condition.

A

Decreased

48
Q

During the upstroke of an action potential, what is the net driving force for K+ in a muscle cell? Is it being driven in or out of the cell?

A

+136mV; (increased) net outward force

[+40mV - (-96mV) = +136mV]

49
Q

During the upstroke of an action potential, what is the net driving force for Na+ in a muscle cell? Is it being driven in or out of the cell?

A

-26mV; (decreased) net inward force

[+40mV - (+66mV) = -26mV]

50
Q

During the upstroke of an action potential, what is the net driving force for Cl- in a muscle cell? Is it being driven in or out of the cell?

A

+130mV; (increased) net inward force

[+40mV - (-90mV) = +130mV]

51
Q

At the peak of an action potential, what is the net driving force for K+ in a muscle cell? Is it being driven in or out of the cell?

A

+151mV; large net outward force

[+55mV - (-96mV) = +151mV]

52
Q

At the peak of an action potential, what is the net driving force for Na+ in a muscle cell? Is it being driven in or out of the cell?

A

-11mV; small inward force

[+55mV - (+66mV) = -11mV]

53
Q

At the peak of an action potential, what is the net driving force for Cl- in a muscle cell? Is it being driven in or out of the cell?

A

+145mV; large net inward force

[+55mV - (-90mV) = +145mV]

54
Q

During the downstroke of the action potential, the driving forces on both K+ and Cl- [increased/decreased]compared to the +55mV at the peak of the action potential.

A

Decreased

55
Q

During the downstroke of the action potential, the driving forces on Na+ [increased/decreased]compared to the +55mV at the peak of the action potential.

A

Increased

56
Q

Charge movement without ionic current flow through the membrane; initially depolarizes inactive membrane

A

Capacitive current

57
Q

Name the 4 steps of capacitive current.

A
  1. Na+ current moves from active to inactive region of membrane inside cell
  2. Positive charge displaces or neutralizes negative charge
  3. Positive charge repelled off outside membrane
  4. Positive charge outside of cell is replaced with a negative charge (capacitive current)

Physiology (15 decks)

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