Neurones, Nerve Fibres and Peripheral Nerves Flashcards Preview

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

Flashcards in Neurones, Nerve Fibres and Peripheral Nerves Deck (83):
1

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

#NAME?

2

What are the main functional components of the nervous system?

Brain and spinal cord

3

How are the brain, spinal cord and nerves related?

They are all interconnected

4

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

#NAME?

5

How many pairs of cranial nerves are there?

12 pairs

6

How many pairs of segmental nerves are there?

31

7

What is the nervous system made up of?

Trillions of nervous system cells

8

What does analysis show of nerve cells?

They can be broadly divided into 2 types

9

What are the 2 cell types of the nervous system?

#NAME?

10

How much of the nervous system cells are glia?

90%

11

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

Neurones

12

What is the purpose of neuroglia?

Brings form to nervous system

13

How can neuroglia be divided?

Into microglia and macroglia

14

Where does microglia come from?

Bone marrow

15

Where does macroglia come from?

Nervous tissue

16

How can glia be stained in micrographs?

By the Golgi-Silver Impregnation technique

17

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

Which division of nervous system in question

18

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

They probably don't

19

What are the characteristic neuroglia in the CNS?

- Astrocytes
- Oligodendrocytes
- Ependyma 
- Microglia

20

Which neuroglia in the CNS have the largest cell count?

Astrocytes

21

What do the astrocytes constitute?

The blood-brain barrier

22

What is the purpose of astrocytes?

#NAME?

23

What is the purpose of oligodendrocytes?

Myelination

24

How many cells can oligodendrocytes myelinate at a time?

Up to 250

25

What happens if an oligodendrocyte become damaged?

Lots of subsequent cells affected

26

What do ependyma do?

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

27

What is the purpose of microglia?

Immunity and inflammation

28

How do microglia assist in immunity and infection?

They remove infected material

29

What happens if the microglia are faulty?

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

30

What are the characteristic neuroglia of the PNS?

- The Schwann cell
- Sattelite cells 
- Microglia

31

What are the main functions of Schwann cells?

Insulation of the peripheral nerve axons

32

What is the purpose of insulation of peripheral nerve axons?

Speed up impulse conduction

33

How many Schwann cells myelinate 1 axon?

1

34

What do Satellite cells do?

Physical support of neurones in the PNS

35

What is a neurone?

The specialised functional unit of the nervous system

36

What are the main features of the neurone?

#NAME?

37

What do some neurones have?

Specialisations of cell bodies called dendrites

38

What does the neurone require when staining?

Different staining for different parts

39

What is the purpose of the cell body?

The ‘engine’ of the neuroen

40

How do cell bodies vary?

In size and shape

41

What does the neurone cell body contain?

- Nucelus 
- Nissl substance
- Golgi apparatus

42

What is the purpose of the Nissl substance?

Protein synthesis

43

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

Packaging of transmitters into vesicles

44

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

Relatively grey

45

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

The grey matter

46

What makes up the white matter of the nervous system?

Axons

47

What is a typical example of grey matter in CNS?

Nerve nuclei

48

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

Ganglia

49

What else is the term ganglion used to describe?

Cysts and raised inguinal lymph nodes

50

What happens in the initial segment?

Where the action potential is initiated

51

What is different about the initial segment?

It has a high volume of voltage-gated sodium channels

52

How do axons of neurones differ from each other?

#NAME?

53

Which axons are not myelinated?

Thin ones

54

What do non-myelianted axons have?

Intermingling sodium and potassium channels

55

What axons are myelinated?

Thick axons

56

What is conduction of electrical impulses corrected to?

The level of axonal myelination

57

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

100 times

58

Give 4 diseases that demyelinate axons

- Multiple Sclerosis 
- Guillain Barre
- Diabetes
- Polyneuropathies

59

Where does demyelination result in faster conduction?

Axons of x-sectional diameter less the 1µm

60

What happens in an unmyelinated axon?

There is depolarisation along entire length of axon

61

What happens in a myelinated axon?

There is depolarisation only at Nodes of Ranvier

62

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

Average of 100µm

63

How are any two successive Schwann cells separated?

By an unmyelinated axonal segment known as node of Ranvier

64

How big is a node of Ranvier?

~1µm in length

65

What is the appearance of nerves?

Reflective, shiny, whiteish

66

What causes the appearance of nerves?

Their myelin sheathing

67

What is a peripheral nerve a typical example of?

White matter of the PNS

68

What is a nerve covered in?

Epineurium

69

What does the nerve contain?

Blood vessels

70

How are groups of nerves arranged?

In groups called fascicles

71

What covers fascicles?

Perineurium

72

What is found in fascicles?

Axons

73

What covers axons?

Endoneurium

74

How do metastases travel?

In the plane of the epineurium

75

What are the membranous envelopes of cranial and spinal nerves?

- Epineurium 
- Perineurium 
- Endoneurium

76

What attaches epineurium to the adjacent nerve fascicle?

Interfascicular bonds

77

What are the membranous envelopes of fibres tracts continuous with ?

Coverings of the brain and spinal cord, called meninges

78

What are the membranous envelopes of the fibre tracts?

#NAME?

79

What happens to the proximal segment of a severed neurone?

- 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

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

Chromotolysis

81

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

Wallerian regeneration

82

What happens to the distal segment of a severed neurone?

It undergoes Wallerian degeneration

83

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

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