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Flashcards in ToB 16 The Nervous System Deck (111)
1

How many pairs of cranial nerves does the human body possess?

12 pairs

2

How many pairs of segmental/spinal nerves does the human body possess?

31 pairs

3

What type of cell constitutes ~90% of the nervous system?

Glial cell (Glia)

4

Neuronal cells constitute what percentage of the nervous system?

~10%

5

What is the (greek) origin of the word 'glia'?

Glue

6

What is the main function of glia?

To bind and hold the neurones of the nervous system together

7

What type of embryonic tissue is microglia derived from?

Haemopoetic stem cells

8

What type of embryonic tissue is macroglia derived from?

Neuroectoderm

9

How many types of macroglia are present in the CNS, and name them:

1) Astrocytes
2) Oligodendrocytes
3) Ependyma

10

What is the name of the type of glia which causes the differentiation of the capillary endothelial cells in the brain, creating the blood-brain barrier?

Astrocytes

11

What is the main function of Oligodendrocytes?

Myelination of neuronal axons

12

Why can the death of 1 oligodendrocytes have a very significant effect?

1 oligodendrocyte can myelinate up to 250 different axons at 1 time, so the death of that cell will ahve significant effects on the speed of conduction of many different axons.

13

What are the 4 types of glia present in the CNS:

1) Astrocytes
2) Oligodendrocytes
3) Ependyma
4) Microglia

14

What is the function of ependymal cells?

Line the ventriclar system of the brain and central canal of spinal cord, and is involved in production of cerebrospinal fluid.

15

Where are ependymal cells found?

Lining the ventricular system of the brain, and the central canal of the spinal cord

16

Which type of glial cell increases the speed of conduction of a nerve in the central nervous system?

Oligodendrocyte

17

Which type of glial cell lines the ventricular system of the brain?

Ependymal cells

18

Which type of glial cell line the central canal of the spinal cord?

Ependymal cells

19

What is the main function of microglia?

Immune cells of the central nervous system

20

Name the 2 types of macroglia present in the peripheral nervous system:

1) Schwann cells
2) Satellite cells

21

In the peripheral nervous system, how many axons can be myelinated by 1 glial cell?

1

22

What type of glial cell myelinates axons in the peripheral nervous system?

Schwann cells

23

In the central nervous system, how many axons can be myelinated by 1 glial cell?

Up to 250 axons

24

What type of glial cell myelinates axons in the central nervous system?

Oligodendrocytes

25

What is the role of satellite glial cells?

Physically support neurones in the peripheral nervous system

26

What type of glial cell are present in both the cental and peripheral nervous systems?

Microglia

27

What is the maximum number of cell bodies contained within a neurone?

1 cell body per neurone

28

What is the maximum number of axons that a neurone can have?

1 axon per neurone

29

What is the main function of neuronal dendrites?

To increase the surface area of the cell, in order to contact other cells.

30

What are the two necessary parts of a neurone?

1) Cell body
2) Axon

31

What structure do many neurones have to increase their surface area?

Dendrites

32

Name the different types of neuroglia:

1) Microglia
2) Oligodendrocytes
3) Astrocytes
4) Ependyma
5) Schwann cells

33

What is 'Nissl substance'?

The granular substance surrounding the nucleus in the cell body of a neurone, consisting of rER and free ribosomes, and is the site of protein synthesis.

34

What is contained within the cell body of a neurone?

- Nucleus
- Nissl substance
- Golgi apparatus

35

What is the main function of the Golgi apparatus within the cell body of a neurone?

To package neurotransmitter into vesicles

36

What is the approximate size of a cell body of a neurone, in micrometres?

~ 4-120 um

37

What is the name of the membrane which prevents crystal violet dye from being taken up by the nucleus of a neurone?

Peri-nuclear membrane

38

What stain allows us to see the cell body of a neurone?

Crystal-violet (taken up by Nissl substance)

39

In unstained brain slices, why do cell bodies appear a different colour to the axon of a neurone?

Cell bodies contain high amounts of Nissl substance, which absorbs the light creating a grey colour,
Axons do not contain Nissl substance, so reflect the light appearing white.

40

Which part of the neurone contributes to the white matter of the brain tissue?

Axons

41

Which part of the neurone contributes to the grey matter of the brain tissue?

Cell bodies

42

What is the name given to collections of cell bodies in the peripheral nervous system?

Ganglia

43

What does 'ganglia' mean?

Swelling
used to describe cysts and raised nodes, also
collections of nerve cell bodies in peripheral nervous system

44

Where is the 'initial/initiation segment' of a neurone?

The first part of the axon leaving the cell body, is rarely myelinated, so the section between the cell body and the first myelin sheath is the initial/initiation segment

45

In what part of the neurone is an action potential created?

The initial/initiation segment

46

When an action potential is created in a neurone, why is it sent in 2 directions?

To the cell body to inform the cell, and
to the axon terminal to be passed onto another neurone/cell

47

What is the name of the axon membrane beneath a myelin sheath?

Internodal membrane

48

Why do thicker axons tend to conduct an AP faster than thinner axons?

Thicker axons tend to be myelinated, which increases the speed of conduction

49

Why does myelination affect the location of certain ion channels on an axon?

Voltage-gated Na+ channels only need to be present at nodes of ranvier when the axon is myelinated, rather than across the whole of the axon if unmyelinated

50

Name 3 polyneuropathy diseases which demyelinate neurons:

1) Diabetes
2) Multiple sclerosis
3) Guillain-Barré syndrome

51

What is the name of the thin unmyelinated axons which have a faster conduction velocity than if they were myelinated?

C fibres

52

Where does depolarisation of a myelinated axon occur?

At the initial/initiation segment, and nodes of Ranvier

53

What is the approximate length of a node of Ranvier?

~ 1 um

54

What gives most nerves a reflective shiny whitish appearance?

Myelin sheathing

55

What is the name of the connective tissue sheath which surrounds the individual nerve fibres of a peripheral nerve?

Endoneurium

56

Define 'endoneurium':

The connective tissue sheath which surrounds the individual nerve fibres of a peripheral nerve.

57

What is the name of the connective tissue sheath which surrounds a fascicle of nerve fibres within a peripheral nerve?

Perineurium

58

Define 'perineurium':

The connective tissue sheath which surrounds a fascicle of nerve fibres within a peripheral nerve

59

What is the name of the connective tissue sheath which surrounds a peripheral nerve?

Epineurium

60

Define 'epineurium':

The connective tissue sheath which surrounds a peripheral nerve

61

What is the name of the tough outermost meninges which surround the brain and spinal cord?

Dura mater

62

Define 'dura mater':

The toughest outermost meninges which surrounds the brain and spinal cord

63

How many meninges surround the brain and spinal cord?

3

64

Name the three meninges:

1) Pia mater
2) Arachnoid mater
3) Dura mater

65

What is the name given to the delicate middle meninges?

Arachnoid mater

66

Define 'arachnoid mater':

The thin fibrous middle meninges which surrounds the brain and spinal cord,

67

What is the name given to innermost meninges?

Pia mater

68

Define 'pia mater':

The innermost meninges covering the brain and spinal cord

69

Which meninges are highly vascularised?

- Dura mater
- Pia mater

70

Which meninges is avascular?

Arachnoid mater

71

The cell body of a neurone tends to swell and peripherally displace the nucleus if the axon of the neurone is damaged/cut. Why is this?

The cell body is undergoing rapid protein synthesis to begin axon regrowth

72

What is chromatolysis?

The disintegration of the granular Nissl substance within a neuronal cell body, usually occurring due to peripheral nerve damage

73

What is the meaning of the word 'afferent'?

Travelling towards a center

74

What is the meaning of the word 'efferent'?

Travelling away from a center

75

Define 'preganglionic neuron':

A neurone whose cell body lies within the CNS, and whose axon terminates at a ganglion in the peripheral nervous system, synapsing with postganglionic neurones

76

Define 'postganglionic neuron':

A neurone whose cell body lies within the autonomic peripheral nervous system

77

Is a sensory neurone afferent or efferent?

Afferent

78

Is a motor neurone efferent or afferent?

Efferent

79

Which structures encase the CNS?

Cranium
Vertebral column

80

By definition, are sensory neurones within or distinct from the CNS?

Distinct from the CNS

81

The autonomic nervous system can be split into which 3 components?

1) Sympathetic NS
2) Parasympathetic NS
3) Enteric NS

82

Is the enteric NS somatic or autonomic?

Autonomic

83

Define 'somatic nervous system':

The part of the nervous system which controls skeletal muscles under voluntary control

84

Define 'autonomic nervous system':

The part of the nervous system which works without conscious control

85

What is the effector organ of the somatic nervous system?

Skeletal muscle

86

Which nervous system is inactivated during sleep?

Somatic NS

87

Which nervous system is responsible for maintaining homeostasis in the body?

Autonomic NS

88

What are the 2 opposing systems within the autonomic nervous system?

1) Sympathetic
2) Parasympathetic

89

What are the 4 types of effector organs stimulated by the autonomic nervous system?

1) Visceral organs
2) Smooth muscle
3) Cardiac muscle
4) Secretory glands

90

What type of neurone reaches from the CNS to a peripheral ganglion?

Pre-ganglionic neurone (afferent)

91

What type of neurone reaches from a peripheral ganglion to an effector organ?

Post-ganglionic neurone (afferent)

92

What type of neurones are always myelinated (in normal circumstances)?

Pre-ganglionic neurone

93

What type of neurone is never myelinated (under normal circumstances)?

Post-ganglionic neurones

94

Which nervous system induces the 'fight or flight' response?

Sympathetic nervous system

95

What effect does the sympathetic nervous system have on heart rate?

It increases heart rate

96

The human vertebral column is split into which five segments? (In order from top to bottom)

1) Cervical
2) Thoracic
3) Lumbar
4) Sacral
5) Coccygeal

97

In which segments of the vertebral column does the sympathetic nervous system have cell bodies in?

Thoracic
Lumbar

98

Pre-ganglionic sympathetic neurones all secrete which neurotransmitter?

Acetylcholine

99

Post-ganglionic sympathetic neurones all express what type of receptor?

Nicotinic Acetylcholine Receptors (NAchRs)

100

Post-ganglionic sympathetic neurones secrete which neurotransmitter? What is the exception?

Noradrenaline
Acetylcholine is released by the nerves innervating sweat glands

101

Where do most of the pre-ganglionic sympathetic neurones (efferent) synapse?

Paravertebral chain

102

What are the 2 classes of adrenoceptors?

1) Alpha-adrenoceptor
2) Beta-adrenoceptor

103

What name is given to the receptors which respond to adrenaline?

Adrenoceptors

104

What effect does the parasympathetic nervous system have on heart rate?

Reduces heart rate

105

Which branch of the autonomic nervous system promotes digestion?

Parasympathetic NS

106

What part of the CNS does the parasympathetic pre-ganglionic nerves arise from?

Cranial nerves
Sacral region of spinal cord

107

Which branch of the autonomic nervous system has long pre-ganglionic nerves?

Parasympathetic NS

108

Which branch of the autonomic nervous system has short pre-ganglionic nerves?

Sympathetic NS

109

Which branch of the autonomic nervous system has long post-ganglionic nerves?

Sympathetic NS

110

Which branch of the autonomic nervous system has short post-ganglionic nerves?

Parasympathetic NS

111

What neurotransmitter is secreted from pre-ganglionic autonomic neurones?

Acetylcholine