Neuronal Signaling Flashcards

1
Q

An increase in axon diameter results in what?

A

Decrease in resistance within the axon membrane - ions more more rapidly
Increases conduction velocity

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2
Q

Absolute Refractory period

A

NO action potentials can be generated
K channels open - hyperpolarization
Na channels inactive
Directly behind propagating action potential

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3
Q

Voltage gated channels

A

Responds to changes in voltage

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4
Q

Propagation of an action potential from the soma to the axon terminal is unidirectional because…

A

of the inactivation of the Na channels

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5
Q

[Ca] mM

A

ECM 2.5

ICM .0001

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6
Q

Schwann Cells

A

Make myelin in PNS

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7
Q

Voltage

A

Electrical potential difference between two regions of charge

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8
Q

A change in membrane potential from -40 mV to -70 mV…

A

would occu in response to opening K channels

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9
Q

Membrane potential

A

Ionic concentration difference between ECT and Intracellular fluid across membrane results in electrical potential/voltage

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10
Q

Neurons differ in size - they can range from ____ to _____

A

um to meters

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11
Q

Name the 4 glial cells

A

Astrocytes
Oligodendrocytes
Schwann Cells
Microglia

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12
Q

Microglia

A

Macrophage-like - activated by injury

Phagocytize and digest waste products

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13
Q

unipolar neuron

A

one process

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14
Q

Tetrodotoxin

A

Toxin isolated from Japanese Puffer fish

Blocks Na channels/nerve conduction

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15
Q

Guillain-Barre Disease

A

Autoimmune disorder that attacks myelin in the PNS

Acute - days to weeks

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16
Q

Na voltage gated channels

A

High number in axon for depolarization
Closed at resting potential
Opens in response to nerve pulse = Na enters cell
Inactivated for a period after activation - refractory period - will not respond to a new signal

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17
Q

Pseudounipolar neurons

A

One process fromsoma splitting to form 2 axons

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18
Q

Relative Refractory period

A

Action potentials can be generated but at a higher threshold
Na channels closed
K channels open - hyperpolarization
Behind absolute refractory period

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19
Q

What kind of proteins are in the neuronal membrane?

A

Ion pumps
Ion channels
Receptors for neurotransmitters

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20
Q

Which glial cell is most common?

A

astrocytes

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21
Q

[K] mM

A

ECM 4

ICM 130

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22
Q

Equilibrium potential/voltage

A

balance between chemical force (concentration gradient) and electrical force (charge gradient)

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23
Q

Ca voltage gated channels

A

high number in axon terminal for the release of neurotransmitters and docking of vesicles

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24
Q

Ion channel

A

Ions move through pores via diffusion via chemical gradients

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25
Q

Etiology of multiple sclerosis

A

Viral infection triggers

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26
Q

A change in a cell membrane potential that makes it more negative…

A

hyperpolarization

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27
Q

What two factors affect the conduction velocity in axons?

A

Axon diameter

Myelination

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28
Q

State dependent blockade

A

More effecting at blocking channels/nerve conduction during the open or inactivated state

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29
Q

Symptoms of multiple sclerosis

A

Loss of sensation/motor function in multiple sites

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30
Q

tx of guillain barre disease

A

Immunoglobulins and plasmapheresis (remove plasma, which may be source of immune factors)

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31
Q

A change in a cell membrane potential that makes it more positive is….

A

depolarization

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32
Q

Neurons are cells with…

A

polarity that signals using electrical and chemical activity

33
Q

Which two glial cells have the same function but inn different parts of the nervous system?

A

Oligodendrocytes

Schwann Cells

34
Q

An increase in myelination of an axon results in what?

A

Increase in the axon membrane resistance, decreasing the leakage of Na
Increases conduction velocity

35
Q

Frequence of guillain barre disease

A

1 in 100,000

36
Q

How to axon hillocks accomodate the integration of local potentials?

A

Lots of Na channels

37
Q

What is the reason for hyperpolarization during an action potential?

A

prevents reverse action potential

Limits action potential firing

38
Q

Which ions are ion channels slective for?

A

Na
K
Cl
Ca

39
Q

Threshold potential

A

If the integrated local potential is depolarized enough to open enough Na channels to reach the threshold potential, an action potential is initiated

40
Q

Action potential

A

Brief, transient change in membrane potential (1 ms)
Polarity of membrane reverses from -60 mV to +40 mV
Results from time dependent, voltage sensitive channels
Propagates from soma to axon terminal in all or none fashion

41
Q

What are 3 things of note when calculating the equilibrium potential?

A
  1. Very few ions actually move
  2. Potential difference occurs near membrane
  3. At equilibirum, no net movement of K+ ions
42
Q

Oligodendrocytes

A

Make myelin in CNS

43
Q

The Na/K pump is ELECTROGENIC - what does this mean?

A

It generates a voltage

-2 mV

44
Q

How does ion gating differ between Na and K?

A

Na - open - inactive - closed

K - no inactivation

45
Q

Multiple sclerosis

A

Autoimmune disorder which attacks myelin in the CNS

Chronic - months to years - relapsing/progressively worse

46
Q

Saltatory propagation

A

Action potential jumps from one Node of Ranvier to the next

= increase in conduction velocity

47
Q

What is the structure of the neuronal membrane?

A

Lipid bilayer

48
Q

Equilibirum potential

A

membrane potential at which the electrical gradient and chemical (concentration) gradient become = in magnitude but in opposite direction

aka the electrical potential required to offset the chemical gradient

49
Q

K voltage gated channels

A

high number in axon for repolarization and hyperpolarization

50
Q

Multipolar neuron

A

Most common

Multiple processes

51
Q

Nodes of Ranvier

A

Gaps of axon between myelinated portions

Where Na can anter axon

52
Q

[Cl] mM

A

ECM 120

ICM 5

53
Q

Tx of multiple sclerosis

A

Glucocorticoids - adrenal steroids to decrease inflammation

54
Q

What is the function of the neuronal membrane?

A

Barrier to ion flow
Storage for ionic charge
Support of integral membrane proteins

55
Q

The Nernst equation calculates

A

Calculates the equilibrium potential of a single ion IF only 1 ion channel open at a time

56
Q

Ion pump

A

Ions move through membrane AGAINST chemical gradient

57
Q

Ligand gated channels

A

High number in dendrites and in cell bodies that receive synaptic input
Neurotransmitters to dendrites

58
Q

Which cytoskeletal proteins are in axons and dendrites? What are their function?

A

Microtubules
Neurofilaments
Structural support

59
Q

Dendrites receive ______ signals from axons and transmits _______ signals to cell body

A

chemical

Electrical

60
Q

Local potentials generated in dendrites can cause…

A
  1. excitatory neurotransmitters cause a depolarization

2. inhibitory neurotransmitters cause a hyperpolarization

61
Q

Local potentials are INTEGRATED (summated) where?

A

At the axon hillock - first portion of axon extending from cell body

62
Q

Bipolar neuron

A

two major processes

63
Q

[Na] mM

A

ECM 140

ICM 15

64
Q

Which type of neuron is most common?

A

multipolar

65
Q

Internodes

A

Myelinated portions of axon

66
Q

Neuronal cell bodies contain which organelles?

A
Nucleus
Endoplasmic reticulum/ribosomes (protein synthesis)
Golgi (protein processing and packaging)
Mitochondria
Lysosomes
67
Q

symptoms of guillain barre disease

A

Loss of sensation/muscle control

Initially hands and feet then moves to torso

68
Q

What are two properties of ion channels?

A

Ion gating

Ion selectivity

69
Q

An axon is a single process extending from the cell body which transmits _______ activity to terminals that release ______

A
electrical (action potential)
chemical signals (neurotransmitter)
70
Q

etiology of guillain barre disease

A

Infection triggers immune response

71
Q

Na/K pump

A

Ion pump
Requires ATP
Electrogenic - generates voltage (-2mV)
Responsible for maintaining Na/K concentration gradient

72
Q

Which organelles are in the axon?

A

cytoskeletal proteins
mitochondria
vesicles - neurotransmitter

73
Q

Synaptic potential

A

difference in voltage between the outside and inside of a postsynaptic neuron

74
Q

What is the frequency of multiple sclerosis

A

1 in 1,000

75
Q

Astrocytes

A
"Star shaped"
Structural support
Uptake of ions - K
Fill gaps via proliferation - injury
Neurotransmitter metabolism
Blood flow
76
Q

Local anaesthetics - lidocaine

A

Blocks sodium channels/nerve conduction

77
Q

Membrane potentials with single ions are generated by the selective movement of a single ion due to _________ gradient across membrane

A

electrochemical

78
Q

Which organelles are in dendrites?

A

endoplasmic reticulum
mitochondria
cytoskeletal proteins

79
Q

Ligand gated ion channels are also called

A

ionotropic receptors