Brainscape's Knowledge GenomeTM

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


See full index

Physiology > Week 5: membrane potentials and action potentials > Flashcards

Week 5: membrane potentials and action potentials Flashcards

1
Q

Potassium concentrations in/out of nerve cell

A

Potassium is high concentration in nerve fiber membrane

low concentration outside cell membrane

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

How does electropositivity occur outside cell membrane

A

Ions flow out and carry positive electrical charge with them

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

Effect of positive ion outflow of cell membrane

A

Diffusion potential decreases (until is ceases)

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

Diffusion potential at which K+ diffusion ceases (from in–>out of cell)

A

-94 mV

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

Diffusion of sodium in/out of cell and overall membrane potential

A

Sodium diffuses into cell (positive charge) and creates overall potential +61mV

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

Nerst equation explaination

A

Greater ration of ions = greater tendency for ion do move in one direction = greater Nerst potential REQUIRED to PREVENT additional diffusion

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

The Nerst equation explores

A

The relation of diffusion potential to ion concentration difference

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

Sodium concentration (inside vs outside of cell)

A

High outside of membrane, low inside

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

Nerst Potential refers to inside or outside of membrane?

A

Inside of membrane

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

Nerst potential assumes that potential of extracellular fluid =

A

0

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

Nerst potential of a membrane is positive if

A

Ion diffusing in—>out is negative

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

Nerst potential of a membrane is negative if

A

ion diffusing from inside—- out is positive

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

The Goldman Equation

A

Calculates the diffusional potential when membrane is permeable to many ions

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

The Nerst equation assumes that

A

A membrane is only permeable to one ion

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

The Goldman Equation factors in: (3)

A
  1. Polarity of electrical charge of each ion
  2. Permeability of the membrane (K+ is more permeable than Na+)
  3. Concentration of ions on the inside and outside
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What ions are most important for developing membrane potentials in nerve and muscle fibers?

A

Na, K, Cl

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

_______ is the key for determining voltage

A

Permeability

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

Which ions have changing permeability during action potentials?

A

Na and K

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

Which ions have fixed permeability during action potentials

A

Cl

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

Resting membrane potential of nerves(calculated from goldman equation)

A

-70 mV

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

2 Factors that account for the negative membrane potential

A
  1. Sodium-Potassium pump pumps more + ions out than in (3 Na out, 2 K in)
  2. K+ leak channels out
    more positives out of cell than into cell = negative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Does Na or K have a higher magnitude inside:outside ratio

A

Potassium
K+ inside: K+ outside = 35

Na+ inside: Na+ outside = 0.1

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

How do neuron action potentials begin?

A

Sudden change from resting negative membrane potential —> positive potential

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

Once a neuron’s action potential starts, it

A

moves along the nerve fiber until the fiber’s end

23
Q

Action potential stages:

A
  1. Resting
  2. Depolarization
  3. Repolarization
24
Q

Depolarization definition and cause

A

Potential rapidly rises (becomes less negative)

cause: membranes become more permeable to sodium

25
Q

Repolorization definition and cause

A

Re-establishment of normal negative resting potential

Cause: Sodium channels close and potassium channels open (K+ rapidly diffuses out of cell)

26
Q

Once action potential threshold is met:

A

It always fires and always goes the length of the neuron

27
Q

Sodium permeability is facilitated by

A

Activation/Inactivation gate

28
Q

Sodium gate at rest (neuron action potentials)

A

Gate is closed, prevents entry of sodium ions into nerve fibers

29
Q

What happens to trigger activation of depolorization?

A

membrane potential becomes less negative

30
Q

What is the trigger range (mV) for depolarization

A

-70 - -50 mV

31
Q

What happens to sodium gates when action potential depolarization threshold is met?

A

It has a conformational change and Na+ permeability rapidly increases

32
Q

What causes the increase in mV that lead to activation of depolarization

A

Na+ outflow by sodium-potassium pump (3+ out, 2+ in = more positive on the outside)

33
Q

Inactivation of Na+ gate

A

Voltage quickly increases with inflow of Na+ and gate quickly shuts
(happens within a few 10,000ths of a second)

34
Q

Repolorization of membrane potential

A

Sodium channels close (no more + flows in) and Potassium channels open (more + flows out)

35
Q

At rest, potassium channels are

A

Closed

36
Q

As the membrane becomes more positive, potassium channels

A

Open and potassium diffuses out

37
Q

During depolarization, __________ flows in _____

A

During depolarization, Na+ flows in rapidly

38
Q

During repolorization, ______ flows in_____

A

During repolarization, K+ flows out slower

39
Q

During conductance, at rest K concentration is ____ than sodium (inside cell)

A

greater than

40
Q

During action potential, sodium conductance _____

A

Increases 5000 fold

41
Q

How does Ca+ contribute to membrane potential becoming positive?

A

Voltage gated channels allow Ca+ to flood in, increasing overall + charge

42
Q

Deficits in Ca+ lead to______. Why?

A

highly excitable neurons

Neuron can’t get all the way to resting potential - it does not repolarize all the way

43
Q

What is the threshold for action potential?

A

-65 mV?

44
Q

Propagation means

A

impulse travels in all directions

45
Q

Action potentials follow an _______ principle

A

all-or-nothing

46
Q

Schwann cells create

A

myelin sheath in myelinated axons in PNS

47
Q

Myelination _____ speed of transmission

A

insulates and increases speed of tranmission

48
Q

Ions flow through _____

A

Nodes of Ranvier

49
Q

Electrical currents flow through

A

Extracellular fluid and axoplasm

50
Q

Myelination ____ velocity of nerve transmission

A

increases nerve transmission

51
Q

Oligodendroytes

A

Similar to myelination, but in central nervous system

52
Q

What factors change sodium ion diffusion/cause excitation (3)? Examples?

A
  1. Mechanical (pressure distorts membrane)
  2. Chemical (i.e excitatory neurotransmitters/ligands bind and open Na+ gate)
    3.Electrical (membrane potential increases, action potential starts)
53
Q

Membrane stabilizing factors _____ excite ability

A

Decrease

54
Q

Examples of membrane- stabilizing factors

A
  1. calcium ions
    2.Procaine and tetracaine (Na channels more difficult to open)
55
Q

What can create acute local potentials?

A

Small electrical stimulations

56
Q

Refractory period

A

Membrane needs to return to resting potential before it fires again

57
Q

acute sub-threshold potentials

A

Do not trigger a full action potential

58
Q

Saltatory conduction

A

Action potentials occur node to node jumping

59
Q
A

Physiology (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions