Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Block 5 > Phys: Membrane Potentials And Action Potentials > Flashcards

Phys: Membrane Potentials And Action Potentials Flashcards

1
Q

Ungated channels are…

A

selectively permeable to certain substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Transport in ungated channels is determined by:

A

-size
-shape
-charge of channel
-ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Gated channels:

A

-voltage
-ligand/chemical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Example of voltage gated channel:

A

Voltage gate Na+ channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Examples of ligand/chemical channels:

A

nicotinic acetylcholine receptor channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Active transport of Na+ and K+

A

NA+ is pumped out and K+ pumped in to maintain the concentration gradients between ECF and ICF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Simple diffusion and Na+ and K+ occurs vis which channels?

A

Leak channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Simple diffusion of Na+ and K+

A

-K+ channels selectively permit passage of K+ across the membrane
-Na+ channels selectively permit passage of Na+ across the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

A diffusion potential is the…

A

Potential difference generated across a membrane when a charged solute diffuses down its [ ] gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

A diffusion potential can be generated ONLY if…

A

The membrane is permeable to that ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

If a membrane were only permeable to K+ then…

A

K+ would diffuse down [ ] gradient until electrical potential across membrane countered diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The electrical potential that counters net diffusion of K+ is called the…

A

K+ equilibrium potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Ek =

A

-61 X log Ki/Ko

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Na-K ATPase is necessary for resting membrane potential(RMP) allowing for ____ Na+ out and ___ K+ in makes inside more __________

A

3, 2, negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If a membrane were permeable to only Na+ then…

A

Na+ would diffuse down its concentration gradient until potential across membrane counters diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The electrical potential that counters net diffusion of Na+ is called the:

A

Na+ equilibrium potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

ENa =

A

-61 X log Nai/Nao

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Membrane potential for K+

A

-94mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Na+ membrane potential

A

+61mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Vm value range

A

-90 to -70mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why is Vm so close to Ek?

A

The membrane is far more permeable to K+ than Na+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Goldman-Hodgkin-Katz equation calculates the…

A

Vm when more than one ion is involved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

The resting membrane potential is closest to the equilibrium potential for…

A

The ion with the highest permeability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does increasing K+ permeability have on Vm?

A

Will cause membrane potential to become more negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What effect does increasing Na+ permeability have on Vm?

A

Membrane potential will become more positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the effect of high and low plasma potassium on threshold potential?

A

-high potassium levels depolarize the cell membrane bringing it closer to the threshold
-low potassium levels hyperpolarize it, moving it further away from the threshold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the effect of high and low plasma potassium on membrane potential?

A

-high potassium brings the membrane potential closer to zero
-low potassium moves it further away from zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Terms for resting and action potentials:

A

-depolarization
-hyper polarization
-overshoot
-repolarization
-excitability
-threshold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Overshoot is…

A

Positive to 0 mV

30
Q

Repolarization:

A

process where a cell membrane potential returns to its resting negative state after experiencing a depolarization phase

31
Q

Threshold

A

Membrane potential at which an action potential is triggered

32
Q

An increase in extracellular [K+] increases the excitability of the cell becasue…

A

The resting membrane potential is closer to the threshold potential

33
Q

What is the most common cause of muscle tetany?

A

Hypocalcemia

34
Q

How does low calcium levels in blood cause tetany?

A

Low calcium increases excitability of nerve axons by causing sodium channels to open following very small increases in Vm

35
Q

How do calcium ions affect Na channel?

A

-decrease in number of Ca ions reduces the threshold required to open sodium gate
-threshold potential is more negative and closer to Vm when plasma calcium is low

36
Q

Hyperkalemia is one of the deadliest electrolyte disorders becasue of….

A

Deadly cardiac arrhythmias

37
Q

Initial treatment of hyperkalemia should be…

A

Intravenous administration of calcium

38
Q

an action potential is a…

A

Regenerating depolarization of membrane potential that propagates along an excitable membrane

39
Q

Propagates definition:

A

Conducted without decrement

40
Q

Excitable definition:

A

Capable of generating action potentials

41
Q

Action potential basics:

A

-all-or-nothing
-constant amplitude (no summation)
-initiated by depolarization
-involves change in permeability
-rely on voltage gated ion channels

42
Q

Threshold voltage is usually…

A

15 to 13 mV positive to resting potential

43
Q

Action potentials can be induced in nerve and muscle by______________________

A

Extrinsic stimulation

44
Q

Fibers with _______ diameter conduct faster

45
Q

To find myelinated fiber velocity:

A

Mylinated Fiber diameter (mm) X 4.5 = velocity(m/s)

46
Q

Velocity of unmyelinated fiber :

A

Unmyelinated fiber diameter = velocity

47
Q

Function of action potentials:

A

-deliver sensory info to CNS
-information coding
-rapid transmission over distance
-in non-nervous tissue, initiate cellular responses

48
Q

Cellular responses that action potential scan control:

A

-muscle contraction
-secretion

49
Q

During upstroke of action potential:

A

-Na+ perm. Increases due to opening of Na+ channels
-membrane approaches ENa

50
Q

During downstroke of action potentials:

A

-Na perm decreases due to inactivation of Na+ channels
-K perm increases due to opening of K+ channels -> mem potential approaches EK

51
Q

After hyperpolarization of the membrane following an action potential…

A

increased K+ conductance due to delayed closure of K+ channels

52
Q

Ion channel structure:

A

-proteins span membrane
-have water filled channel than runs though protein

53
Q

Ion channel properties:

A

-have conducting states and non-conducting states
-transition between states = gating

54
Q

Channels “gate” in response to:

A

-changes in membrane potential
-occupation of receptor
-mechanical forces

55
Q

Permeability of axon membrane to ions is determined by:

A

Number of open channels

56
Q

Ion channels are usually_____________________

A

Selectively permeable

57
Q

Ion channels are selectively permeable to:

A

-specific ions
-classes of ions

58
Q

What does it mean to be permeable to classes of ions?

A

Some channels are selective to only cations over anions, for example

59
Q

Ion channel gating refers to…

A

Transition between different states that reflect different conformational states of channel proteins

60
Q

Activation gating transition:

A

Opening of channel when membrane is depolarized

61
Q

Deactivation gating transition:

A

Closure of channel when membrane depolarizes

62
Q

Depolarization causes:

A

-Na+ channels to activate
-prevent inactivated channels from passing ions
-K+ channels show activation but NOT inactivation

63
Q

K+ channels only ____________ and the rate of opening is much ___________ than the Na+ channels

A

Activate, slower

64
Q

Voltage gated channels are _______________ for most action potential

65
Q

If voltage gated channel is blocked….

A

No AP will occur (paralysis)

66
Q

What two things can block AP?

A

-tetrodotoxin
-lidocaine

67
Q

Etraethylammonium (TEA) blocks the:

A

-voltage gated K+ channels
-outward K+ current
-repolarization

68
Q

Refractory periods limit the…

A

Maximum frequency if action potentials

69
Q

Absolute refractory peroid

A

-AP not possible due to volatile inactivation of Na+ channels
-gates are in closed position until cell is repolarized back to resting potential and Na+ channels have recovered

70
Q

Relative refractory period:

A

-greater than normal stimulus required to elicit AP
-higher K+ conductance than whats present at rest
-more inward current needed to bring membrane to threshold for next AP

Block 5 (46 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions