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GENERAL PHYSIOLOGY > membrane potential > Flashcards

membrane potential Flashcards

1
Q

receive, process and transmit
information to other cells

A

Neurons

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2
Q

metabolic maintenance

A

Soma

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3
Q

receptive surface
that brings signals from other
neurons toward the cell body

A

Dendrites

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4
Q
  • Nerve Fibers
  • conduct
    signals away from the cell
  • carry information for long
    distances with high fidelity
    and without loss
A

Axons

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5
Q

Afferent neuron

A

sensory

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6
Q

efferent nueron

A

motor

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7
Q

surface membrane of motor-neuron
dendrites & soma

A

innervated

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8
Q

Soma integrates input to initiate…

A

Action potential (AP)

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9
Q

Action Potential

A

nerve impulse

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10
Q

AP is carried from the…

A

spike-initiating zone

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11
Q
  • fundamental property of cells resulting from an
    excess of negative charges on side of the plasma
    membrane and an excess of positive charges on the
    other side
  • source of potential energy to move molecules across
    membranes
  • excitable cells use changes in membrane potential as communication signals
  • critical for allowing the coordinated movements of cells and organisms
A

Membrane potential

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12
Q

every cell has a ______ or ________ across
its plasma membranes

A

Voltage, membrane potential

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13
Q

localized electrical gradient
across membrane

A

Membrane potential

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14
Q
  • negative
  • are more concentrated within a cell
A

Anions

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15
Q
  • positive
  • are more concentrated in the extracellular
    fluid
A

Cations

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16
Q

microelectrode connected to a reference electrode via a
voltmeter (voltage drop across the circuit)

A

Measures membrane potential

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17
Q

an unstimulated cell usually has a resting potential of ….

A

-70mV

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18
Q

equal numbers of anion and cations

A

Electroneutral

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19
Q

Excess negative charge inside

A

draw positive charges into the
cell

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20
Q

more potassium leaves the cell

A

the electrical force
increases to a level that balances the driving force from the
potassium concentration gradient

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21
Q

potassium ions continue to
move, inward and outward fluxes exactly balance each other

A

equilibrium potential

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22
Q

represents the sum of the equilibrium potentials of all
the relevant ions

A

Goldman-Hodgkin-Katz equation

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23
Q

• K+ the principal intracellular cation
• Na+ is the principal extracellular cation

A

Cations

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24
Q

• proteins, amino acids, sulfate, and phosphate are the
principal intracellular anions
• Cl– is principal extracellular anion

A

Anions

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25
Q

the concentration of K+ is greater inside
the cell, while the concentration of Na+ is greater outside the
cell

A

at resting potential

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26
Q

use the energy of ATP to maintain
these K+ and Na+ gradients across the plasma membrane

A

Sodium-potassium pumps

27
Q

opening of ion channels in the plasma membrane

A

converts
chemical potential to electrical potential

28
Q

contains many open K+
channels and fewer open Na+ channels; K+ diffuses out of the
cell

A

neuron at resting potential

29
Q

Anions trapped inside the cell

A

ell contribute to the negative
charge within the neuron

30
Q
  • always open
  • allow ions to
    diffuse across the plasma membrane
A

Non-gated ion channels

31
Q
  • can generate large changes in their
    membrane potential
  • gated ion channels
  • alters the membrane‘s
    permeability to particular ions, which in turn alters the
    membrane potential
A

Excitable cells

32
Q

open or close in response to a
chemical stimulus

A

chemically-gated ion channels (ligand-gated ion
channels)

33
Q

open or close in
response to a change in membrane potential

A

voltage-gated ion channels

34
Q

changes in membrane potential of neuron give
rise to

A

nerve impulse

35
Q
  • are changes in membrane
    potential
  • magnitude of the change in membrane potential
    varies with the strength of the stimulus
A

graded potentials

36
Q

Gated K+ channels open
–> K+ diffuses out of the
cell —> the membrane
potential becomes
more negative

A

Hyperpolarization

37
Q

Gated Na+ channels
open –> Na+ diffuses
into the cell –> the
membrane potential
becomes less
negative

A

Depolarization

38
Q

All or Nothing
Depolarization

A

Action Potential

39
Q

if graded potentials sum
to »-55mV a ______ is achieved

A

Threshold potential

40
Q

triggers an action
potential

A

Threshold potential

41
Q

@ gates of Votage-gated Na+

A

closed activation
open inactivation

42
Q

open rapidly in response to
depolarization

A

closed activation

43
Q

gates close slowly in response to
depolarization

A

open inactivation

44
Q

During the _______, the threshold is
crossed, and the membrane potential
increases

A

rising phase

45
Q

During the _______, voltage-gated
Na+ channels become inactivated;
voltage-gated K+ channels open, and K+
flows out of the cell

A

Falling phase

46
Q

During the _________, membrane permeability to K+ is at first higher than at rest, then voltagegated K+ channels close; resting potential is restored

A

undershoot

47
Q

During the ___________ after an action
potential, a second action potential cannot be
initiated.

A

refractory period

48
Q

a result of a temporary
inactivation of the Na+ channels.

A

refractory period

49
Q

– in myelinated neurons only unmyelinated regions of the axon
depolarize
• thus, the impulse moves faster than in unmyelinated neurons

A

Saltatory conduction

50
Q

action potential travels directly from the presynaptic
to the postsynaptic cells via gap junctions

A

Electrical Synapses

51
Q
  • more common than electrical synapses
  • postsynaptic chemically-gated channels exist for ions
    such as Na+, K+, and Cl-
  • depending on which gates open the postsynaptic neuron
    can depolarize or hyperpolarize
A

Chemical Synapses

52
Q

a region where
neurons nearly touch and
where nerve impulse is
transferred

A

Synapse

53
Q

Small gap between neurons

A

Synaptic cleft

54
Q

Transmission across a
synapse is carried out by

A

Neurotransmitters

55
Q

Primary Factors Influencing Impulse Transmission

A

Axon diameter
Myelination
Temperature

56
Q

typically around 1 micrometer

A

Axon diameter

57
Q

formation of the myelin sheath around
a nerve

A

Myelination

58
Q

the lower the temperature, the
slower the impulses move.

A

Temperature

59
Q

velocity of impulse
propagation varies as a
function of

A

axon diameter
and myelination

60
Q

increase the transmembrane resistance and
decrease the effective neuronal membrane capacitance

A

Myelination

61
Q

the
number of membrane layers wrapped around the axon

A

Resistance increases (cytoplasm and extracellular fluid)

62
Q

myelin layer in very thich

A

Capacitance decreases

63
Q
  • in myelinated neurons only
    – unmyelinated regions of the axon depolarize
  • thus, the impulse moves faster than in unmyelinated
    neurons
A

Saltatory conduction

GENERAL PHYSIOLOGY (8 decks)

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