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BIO108 - Gen. Physiology > Lec 5: Membrane Potential > Flashcards

Lec 5: Membrane Potential Flashcards

1
Q
  • Functional Units of Nervous System
  • receive, process and transmit information to other cells
A

Neurons

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2
Q

Three main parts of neuron

A
  • Soma
  • dendrites
  • Axon
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3
Q

metabolic maintenance

A

Soma

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4
Q

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

A

Dendrites

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5
Q
  • conduct signals away from the cell
  • carry information for long distances with high fidelity and without loss
A

Axons (nerve fibers)

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6
Q

Types of neurons

A
  • sensory or afferent neuron
  • motor or efferent neuron
  • interneuron
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7
Q

carry signals from sensory receptors

A

sensory or afferent neuron

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8
Q

transmit signals from the CNS to muscles or glands, leading to an action or response

A

Motor or efferent neuron

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9
Q

act as connectors or intermediaries between sensory and motor neurons.

A

Interneurons

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10
Q

Transmission of signals in a single neuron

A
  • surface membrane innervated
  • action potential initiation
  • AP carried from spike-initation zone to axon terminal
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11
Q

integrates input to initiate an action potential

A

Soma

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12
Q

surface membrane of motor-neuron dendrites & soma are ____

A

Innervated

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13
Q

Where is the spike-initiating zone of a motor neuron located

A

near axon hillock to the axon terminal

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14
Q

Potential target of AP when it reach axon terminal

A

Skeletal muscle cell or glands

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15
Q
  • Localized electrical gradient
  • electrical potential differences across the cell membrane caused by different concentration of K+, Na+ and Cl- ions
A

Membrane potential

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16
Q

Membrane potential of neurons is usally between ___ and ___ mV

A

-60 to -80 mV

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17
Q

Excitable cells use changes in membrane potential as

A

communication signals

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18
Q

location of excess of negative charges

A

Plasma membrane side

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19
Q

location of excess positive charges

A

on the other side

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20
Q

Every cell has what?

A
  • Voltage or membrane potential across its plasma membrane
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21
Q

is a localized electrical gradient across membrane

A

Membrane potential

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22
Q

are more concentrated within a cell

A

Anions (negative)

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23
Q

are more concentrated in the extracellular fluid

A

Cations (positive)

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24
Q

Factors affecting membrane potential

A
  • Concentration gradient for an ion
  • Membrane that is permable to that ion
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25
Q

measures membrane potential

A

Voltmeter

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26
Q

Resting pontential of an unstimulated cell

A

-70 mV

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27
Q

equal numbers of anion and cations

A

Electroneutral

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28
Q

Channel that potassium ions move out of the cell along concentration gradient

A

Potassium channel

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29
Q

Results when potassium moves out

A
  • Electronegativity
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30
Q

draw positive charges into the cell

A

Excess negative charge inside

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31
Q

How a cell maintain a membrane potential

A
  • Cations
  • Anions
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32
Q

the principal intracellular cation

A

K+

33
Q

is the principal extracellular cation

A

Na+

34
Q

is principal extracellular anion

A

Cl–

35
Q

principal intracellular anions

A
  • Proteins
  • Amino acids
  • Sulfate
  • Phosphate
36
Q

Cations

A
  • K+
  • Na+
37
Q

Anions

A
  • Proteins
  • Amino acids
  • Sulfate
  • Phosphate
  • Cl-
38
Q

at resting potential, concentration of ___ is greater inside the cell, while ___ is greater outside the cell

A

K+ greater inside the cell, Na+ is greater outside the cell

39
Q

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

A

Sodium-potassium pumps

40
Q

converts chemical potential to electrical potential

A

opening of ion channels

41
Q

a neuron at resting potential

A
  • many open K+ channels
  • fewer open Na+ channels
  • K+ diffuses out of the cell
42
Q

allow ions to diffuse across the plasma membrane
- always open

A

Non-gated ion channels

43
Q

can generate large changes in their
membrane potential

A

Excitable cells

44
Q

open or close in response to stimuli

A

Gated ion channels

45
Q

Types of gated ion channels

A
  • Chemically-gated ion channels (ligand-gated ion channels)
  • voltage-gated channels
46
Q

open or close in response to a chemical stimulus

A

Chemically-gated ion channels (ligand-gated ion channels)

47
Q

open or close in response to a change in membrane potential

A

voltage-gated ion channels

48
Q

are changes in membrane potential

A

Graded potentials

49
Q

Types of graded potentials

A
  • Hyperpolarization
  • Depolarization
50
Q
  • Gated K+ channels open
  • K+diffuses OUT of the
    cell
  • the membrane
    potential becomes
    more negative
A

Hyperpolarization

51
Q

Gated Na+ channels open
- Na+diffuses INTO the cell
- the membrane potential becomes less
negative

A

Depolarization

52
Q

All or Nothing
Depolarization

A

The Action Potential

53
Q

What happens when graded potentials sum to approximately -55 mV?

A

Threshold potential is achieved

54
Q

What happens when threshold potential is reaches?

A

Action potential is triggered

55
Q

In resting state, what happens to K+ channels

A
  • Closed voltage-gated K+ channels open slowly, in response to depolarization
56
Q

Two gates of Voltage-gated Na+ channels

A
  • Closed activation
  • Open inactivation
57
Q

open rapidly in response to depolarization

A

Closed activation gates

58
Q

close slowly in response to depolarization

A

Open inactivation

59
Q

Phases of action potential

A
  • Depolarization
  • Overshoot
  • Repolarization
60
Q

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

A

Refractory period

61
Q

What happens to action potential after the refractory period

A

Cannot be initiated

62
Q

a state of recovery that occurs after a neuron has fired an action potential

A

Refractory period

63
Q

Where does nerve impulses propagate?

A

Along the axon

64
Q

the rapid method by which nerve impulses move down a myelinated axon

A

Saltatory conduction

65
Q

Site of excitation

A

Nodes of Ranvier

66
Q

Classes of Synapses

A
  • Electrical synapses
  • Chemical synapses
67
Q

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

A

Electricl synapses

68
Q

more common than electrical synapses

A
  • chemical synapses
69
Q

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

A

Synapse

70
Q

is the small gap between neurons

A

Synaptic cleft

71
Q

Carried out transmission across synapse

A

Neurotransmitters

72
Q

Primary factors influencing impulse transmission

A
  • Axon diameter
  • Myelination
  • Temperature
73
Q

Typical diamter of axon

A

around 1 micrometer

74
Q

formation of the myelin sheath around a nerve

A

Myelination

75
Q

the lower the temperature, the
____ the impulses move.

A

slower

76
Q

varies as a function of axon diameter and myelination

A

Velocity of impulse propagation

77
Q

how fast the membrane
ahead of the active region is brought to threshold by the local-circuit current

A

Conduction velocity of AP

78
Q

Evolutionary adaption to increase length constant

A

Invertibrates - increase axonal diameter

Vertebrates - myelination

BIO108 - Gen. Physiology (20 decks)

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