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Z OLD Tissues of the Body > Neurones, Nerve Fibres and Peripheral Nerves > Flashcards

Neurones, Nerve Fibres and Peripheral Nerves Flashcards

1
Q

What does the nervous system comprise of at the gross level?

A

NAME?

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2
Q

What are the main functional components of the nervous system?

A

Brain and spinal cord

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3
Q

How are the brain, spinal cord and nerves related?

A

They are all interconnected

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4
Q

What 2 units can the brain, spinal and nerve be reconstituted into?

A

NAME?

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5
Q

How many pairs of cranial nerves are there?

A

12 pairs

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6
Q

How many pairs of segmental nerves are there?

A

31

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7
Q

What is the nervous system made up of?

A

Trillions of nervous system cells

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8
Q

What does analysis show of nerve cells?

A

They can be broadly divided into 2 types

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9
Q

What are the 2 cell types of the nervous system?

A

NAME?

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10
Q

How much of the nervous system cells are glia?

A

90%

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11
Q

Which type of nervous system cells are responsible for sophisticated brain function?

A

Neurones

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12
Q

What is the purpose of neuroglia?

A

Brings form to nervous system

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13
Q

How can neuroglia be divided?

A

Into microglia and macroglia

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14
Q

Where does microglia come from?

A

Bone marrow

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15
Q

Where does macroglia come from?

A

Nervous tissue

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16
Q

How can glia be stained in micrographs?

A

By the Golgi-Silver Impregnation technique

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17
Q

What do the sub-types of macroglia vary depending on?

A

Which division of nervous system in question

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18
Q

How do the microglia sub-types vary throughout the body?

A

They probably don’t

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19
Q

What are the characteristic neuroglia in the CNS?

A
  • Astrocytes
  • Oligodendrocytes
  • Ependyma
  • Microglia
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20
Q

Which neuroglia in the CNS have the largest cell count?

A

Astrocytes

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21
Q

What do the astrocytes constitute?

A

The blood-brain barrier

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22
Q

What is the purpose of astrocytes?

A

NAME?

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23
Q

What is the purpose of oligodendrocytes?

A

Myelination

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24
Q

How many cells can oligodendrocytes myelinate at a time?

A

Up to 250

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25
Q

What happens if an oligodendrocyte become damaged?

A

Lots of subsequent cells affected

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26
Q

What do ependyma do?

A

Line the ventricles and central canal of the spinal cord for circulation of cerebrospinal fluid

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27
Q

What is the purpose of microglia?

A

Immunity and inflammation

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28
Q

How do microglia assist in immunity and infection?

A

They remove infected material

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29
Q

What happens if the microglia are faulty?

A

It can affect the BBB, which can lead to infections in the brain

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30
Q

What are the characteristic neuroglia of the PNS?

A
  • The Schwann cell
  • Sattelite cells
  • Microglia
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31
Q

What are the main functions of Schwann cells?

A

Insulation of the peripheral nerve axons

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32
Q

What is the purpose of insulation of peripheral nerve axons?

A

Speed up impulse conduction

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33
Q

How many Schwann cells myelinate 1 axon?

A

1

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34
Q

What do Satellite cells do?

A

Physical support of neurones in the PNS

35
Q

What is a neurone?

A

The specialised functional unit of the nervous system

36
Q

What are the main features of the neurone?

37
Q

What do some neurones have?

A

Specialisations of cell bodies called dendrites

38
Q

What does the neurone require when staining?

A

Different staining for different parts

39
Q

What is the purpose of the cell body?

A

The ‘engine’ of the neuroen

40
Q

How do cell bodies vary?

A

In size and shape

41
Q

What does the neurone cell body contain?

A
  • Nucelus
  • Nissl substance
  • Golgi apparatus
42
Q

What is the purpose of the Nissl substance?

A

Protein synthesis

43
Q

What is the purpose of the Golgi apparatus in the cell body of a neurone?

A

Packaging of transmitters into vesicles

44
Q

How do collections of cell bodies appear in fresh/unstained tissue?

A

Relatively grey

45
Q

What do collections of cell bodies in the nervous system make up?

A

The grey matter

46
Q

What makes up the white matter of the nervous system?

47
Q

What is a typical example of grey matter in CNS?

A

Nerve nuclei

48
Q

What are collections of nerve cell bodies in the PNS known as?

49
Q

What else is the term ganglion used to describe?

A

Cysts and raised inguinal lymph nodes

50
Q

What happens in the initial segment?

A

Where the action potential is initiated

51
Q

What is different about the initial segment?

A

It has a high volume of voltage-gated sodium channels

52
Q

How do axons of neurones differ from each other?

53
Q

Which axons are not myelinated?

54
Q

What do non-myelianted axons have?

A

Intermingling sodium and potassium channels

55
Q

What axons are myelinated?

A

Thick axons

56
Q

What is conduction of electrical impulses corrected to?

A

The level of axonal myelination

57
Q

How many times does a Schwann cell wrap itself around an axon on average?

58
Q

Give 4 diseases that demyelinate axons

A
  • Multiple Sclerosis
  • Guillain Barre
  • Diabetes
  • Polyneuropathies
59
Q

Where does demyelination result in faster conduction?

A

Axons of x-sectional diameter less the 1µm

60
Q

What happens in an unmyelinated axon?

A

There is depolarisation along entire length of axon

61
Q

What happens in a myelinated axon?

A

There is depolarisation only at Nodes of Ranvier

62
Q

How much does the myelin sheath of a single Schwann cell?

A

Average of 100µm

63
Q

How are any two successive Schwann cells separated?

A

By an unmyelinated axonal segment known as node of Ranvier

64
Q

How big is a node of Ranvier?

A

~1µm in length

65
Q

What is the appearance of nerves?

A

Reflective, shiny, whiteish

66
Q

What causes the appearance of nerves?

A

Their myelin sheathing

67
Q

What is a peripheral nerve a typical example of?

A

White matter of the PNS

68
Q

What is a nerve covered in?

A

Epineurium

69
Q

What does the nerve contain?

A

Blood vessels

70
Q

How are groups of nerves arranged?

A

In groups called fascicles

71
Q

What covers fascicles?

A

Perineurium

72
Q

What is found in fascicles?

73
Q

What covers axons?

A

Endoneurium

74
Q

How do metastases travel?

A

In the plane of the epineurium

75
Q

What are the membranous envelopes of cranial and spinal nerves?

A
  • Epineurium
  • Perineurium
  • Endoneurium
76
Q

What attaches epineurium to the adjacent nerve fascicle?

A

Interfascicular bonds

77
Q

What are the membranous envelopes of fibres tracts continuous with ?

A

Coverings of the brain and spinal cord, called meninges

78
Q

What are the membranous envelopes of the fibre tracts?

79
Q

What happens to the proximal segment of a severed neurone?

A
  • The proximal segment soon seals up the damage to prevent leakage, forming a nerve stump
  • Its cell body suddenly swells with increased contents
  • The nucleus is displaced from its central position to peripheral margins
  • The axon usually regrows
80
Q

What is the displacement of the nucleus to peripheral margins known as?

A

Chromotolysis

81
Q

What is the regrowing of the axon being severed known as?

A

Wallerian regeneration

82
Q

What happens to the distal segment of a severed neurone?

A

It undergoes Wallerian degeneration

83
Q

Why does the distal segment of a severed neurone undergo Wallerian degeneration?

A

Because the segment is cut off from the nutritional support of the cell body, and so dies

Z OLD Tissues of the Body (19 decks)

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