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Tissues of the body > Nerves > Flashcards

Nerves Flashcards

0
Q

How many pairs of cranial nerves are there?

A

-12

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1
Q

What are the three gross level components of the nervous system?

A
  • Brain
  • Spinal cord
  • Nerves
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2
Q

How many pairs of segmental (spinal) nerves are there?

A

-31

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3
Q

What are the two cells of the nervous system?

A
  • Glia cells (90%)

- Neurones (10%)

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4
Q

What are the two groups of neurones and in which direction do the carry impulses?

A
  • Sensory/afferent fibres carrying impulses towards the CNS

- Motor/efferent fibres carrying impulses away from CNS

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5
Q

What is the function of the neuroglia?

A

-They are the ‘glue’ of the nervous system

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6
Q

What two divisions of neuroglia are they?

A
  • Macroglia

- Microglia

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7
Q

What is the structure of neuroglia?

A

-Highly branched cells

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8
Q

What three groups can macroglia be divided into?

A
  • Astrocytes
  • Oligodendrocytes
  • Schwann cells
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9
Q

What are the functions of the astrocytes?

A
  • Support cellular matrix of the nervous system
  • Give shape to the brain and spinal cord
  • Act as phagocytes
  • Breakdown glucose->lactate for neuronal nourishment
  • Comprise the blood brain barrier
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10
Q

What is the function of the oligodendrocytes?

A

-Myelinate CNS axons (upto 250 axons/cell)

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11
Q

What is the function of schwann cells?

A

-Myelinate PNS axons (one axon/schwann cell)

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12
Q

When are microglia present in the nervous system?

A

-When there is inflammatory insult to the CNS

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13
Q

What are the functions of microglia?

A
  • Act as immune surveillance cells of CNS

- Act as phagocytes

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14
Q

What are ependyma?

A

-Cilia-like projections which line the ventricles and central canal of the spinal cord for circulation of CSF

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15
Q

What is the function of the satellite cells?

A

-Provide physical support of PNS neurones

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16
Q

What is a dendrite?

A

-Projections from the cell body which receive stimuli from environment or other neurones and carry impulse to cell body

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17
Q

Where is the nucleus located in the cell body?

A

-Centre

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18
Q

What is nissl substance?

A

-aggregations of rER

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19
Q

What is the function of the rER and golgi in the cell body of a neurone?

A
  • rER for protein synthesis

- Golgi for packaging of transmitters into vesicles

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20
Q

Are all axons myelinated?

A

-No

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21
Q

When would an unmyelinated neurone be better?

A

-When the axon has a diameter<1um the impulse will travel faster

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22
Q

Where is the initial segment of an axon located?

A

-Directly next to the cell body

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23
Q

What is the conduction of electrical impulse correlated to?

A

-The level of axonal myelination-> CV=6FD

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24
Q

What makes up grey matter in the CNS?

A

-Collections of cell bodies

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25
Q

What are ganglia?

A

-Collections of cell bodies in the PNS

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26
Q

Do schwann cells just wrap themselves around an axon once?

A

-No it can be up 100x around

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27
Q

Where is the electrical impulse generated from?

A

-The initial segment

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28
Q

What makes up white matter?

A

-Collections of ascending and descending axons as well as glial cells

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29
Q

How are neurones arranged in the spinal cord?

A

-The grey matter takes a butterfly shape inside white matter and has dorsal and ventral horns which contain large cell bodies

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30
Q

What two roots serve the grey matter?

A
  • Dorsal nerve root

- Ventral nerve root

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31
Q

What is the ventral median fissure?

A

-The central point at which white matter converges

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32
Q

What neurones do the ventral cell bodies belong to?

A

-Spinal motor neurones which innervate muscle

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33
Q

What does the dorsal nerve root do?

A

-Carries sensory fibre impulses to the grey matter

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34
Q

Why is white matter white?

A

-Due to its high myelin content

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35
Q

How are the peripheral nerves anatomically arranged?

A

-Axons are arranged into fascicles which make up the peripheral nerve

36
Q

What is epineurium?

A

-Connective tissue which ensheaths the entire nerve

37
Q

What is perineurium?

A

-Connective tissue which ensheaths fascicles and between fascicles carrying interfascicular blood vessels

38
Q

What is endoneurium?

A

-Connective tissue which surrounds a single axon and carries capillaries

39
Q

How does a nerve react to an axon being severed?

A
  • Proximal segment seals up to prevent leakage of contents
  • A nerve stump is formed
  • Distal segment is cut off from nutritional support
  • Distal segment dies and undergoes wallarian degeneration with infiltration of microglia
  • Cell body puffs up with increased contents
  • Nucleus is displaced from the central position to the periphery (known as chromatolysis)
40
Q

What is multiple sclerosis characterised by?

A
  • Selective and patchy loss of myelin sheath

- Axonal destruction and overgrowth of glial tissue

41
Q

Name some diseases of degenerative changes in peripheral nerves

A
  • Peripheral neuropathy (non-inflammatory disease of peripheral nerves)
  • Neuritis (Inflammatory disease)
42
Q

What are the results of degenerative changes in peripheral nerves?

A
  • Sensory loss
  • Motor weakness
  • Both
43
Q

Can nerves be regenerated?

A

-They do not undergo mitosis but damaged peripheral nerves with axons still attached to the cell body can undergo regeneration

44
Q

Define afferent neurone

A

-Neurone which carries signals from periphery to CNS, ie a sensory neurone

45
Q

Define efferent neurone

A

-Neurone which carries impulse from CNS to periphery/effector, ie a motor neurone

46
Q

Define ganglion

A

-Collection of neuronal cell bodies in the PNS

47
Q

Define pre-ganglionic neurone

A

-Neurone immediately proximal to the ganglion

48
Q

Define post-ganglionic neurone

A

-Neurone immediately distal to the ganglion

49
Q

Define effector

A

-Target organ through which the nervous system exerts its action

50
Q

State the divisions of the nervous system

A
  • CNS and PNS both have Afferent and Efferent
  • Efferent split into Somatic and Autonomic
  • Autonomic split into sympathetic, parasympathetic and enteric
51
Q

Which of the efferent divisions is voluntary/involuntary?

A
  • Somatic-> voluntary

- Autonomic-> involuntary

52
Q

What are the general actions of the autonomic nervous system?

A
  • Constancy-> establishes and maintains homeostasis of the internal environment through regulating cardiovascular, digestive respiratory and thermoregulatory systems
  • Control intermittent change in bias
53
Q

What are the effector organs of the autonomic nervous system?

A
  • Visceral organs
  • Smooth muscle
  • Secretory glands
  • Cardiac muscle
54
Q

How are the synapses divided between the sympathetic and parasympathetic nervous systems?

A

-Equally in a series arrangement

55
Q

What is the general layout of the autonomic nervous system?

A
  • Always 2 neurones arranges in series

- One with cell body in CNS and another with cell body in PNS

56
Q

What are the pre-gangloinic neurones also called?

A

-White rami

57
Q

What are the post ganglionic neurones also called?

A

-Grey rami

58
Q

Which axon (pre or post ganglionic) is myelinated?

A

-Pre-ganglionic in the CNS

59
Q

How many meninges are there?

A

-3

60
Q

What is meant by organs receiving dual innervation?

A

-Receive innervation from both the parasympathetic and the sympathetic nervous systems

61
Q

Which nervous system are most organs innervated by?

A

-Autonomic

62
Q

How do the effects of the sympathetic and parasympathetic relate to each other?

A

-The effects are often reciprocal

63
Q

What is autonomic tone?

A

-The balance of inputs and outputs between sympathetic and parasympathetic and the dominance that arises

64
Q

Which glands receive only sympathetic innervation?

A

-Sweat glands

65
Q

What is another name for the sympathetic nervous system?

A

-‘fight or flight’ system

66
Q

When is the sympathetic nervous system dominant?

A

-During stressful situations

67
Q

-What are the overall results of the sympathetic NS?

A
  • Expenditure of energy
  • Diversion of blood to heart and muscles
  • Increase in heart rate, inotropic and chronotropic
  • Increase in bp
  • Reduced blood flow to gut and skin
  • Increased sweating
  • Dilation of retina
68
Q

What is inotrpic?

A

-Increased strength

69
Q

What is chronotropic?

A

-Increased rate

70
Q

Where do nerve fibres of the sympathetic NS exit the CNS?

A

-Spinal cord only

71
Q

Where are the cell bodies of the sympathetic NS located?

A
  • All 12 thoracic segments of the spinal cord (T1-12)

- The first 2 lumbar segments

72
Q

Where are the pre-ganglionic neurones of the sympathetic NS located?

A

-In the spinal cord

73
Q

Pre-ganglionic sympathetic nerve fibres are under what kind of innervation?

A

-Cholinergic

74
Q

What type of receptors do the post ganglionic neurones of the sympathetic nervous system express?

A

-Express nicotinic receptors

75
Q

What kind of innervation are post ganglionic neurones of the sympathetic NS under?

A

-Mostly noradrenergic and some adrenergic

76
Q

Describe the lengths of the pre/post ganglionic neurones of the sympathetic NS?

A

-Short pre-ganglionic neurones and long post-ganglionic neurones (for the majority)

77
Q

What receptors do target organs of the sympathetic NS possess?

A

-a and b

78
Q

What are the three possible levels of neurone termination in the sympathetic NS?

A

1) May synapse in chain at a level corresponding to the level of origin (paravertebral)
2) May synapse at a different level to origin up or down the chain
3) May not synapse in paravertebral chain but at effector organs (splanchnic nerves)

79
Q

-What two exceptions of sympathetic post-ganglionic fibres are not noradrenergic?

A
  • Perspiration

- Ejaculation

80
Q

What are the general actions of the parasympathetic nervous system?

A
  • Reduces heart rate and force of contraction
  • Promotes digestion
  • Promotes bodily functions such as bladder emptying
  • Promotes sleep
81
Q

Where do the nerve fibres of the parasympathetic NS leave the CNS

A

-Through 4 cranial nerves and the sacral segments S2-S4

82
Q

Describe the lengths of the pre/post ganglionic neurones of the parasympathetic nervous system

A

-Long pre ganglionic neurones and short post ganglionic neurones

83
Q

Under what type of innervation are pre-ganglionic neurones of the parasympathetic NS?

A

-Cholinergic

84
Q

Where are most post-ganglionic neurones located?

A

-In the walls of the effector organ

85
Q

What receptors do post-ganglionic neurones of the parasympathetic NS express?

A

-Nicotinic

86
Q

Under what kind of innervation are the post-ganglionic neurones of the parasympathetic NS?

A

-Cholinergic

87
Q

What effects do the sympathetic and parasympathetic have on the following structures, respectively:

  • Eye
  • Saliva
  • Heartbeat
  • Bronchi
  • Peristalsis
  • Liver
  • Bladder
  • Adrenal gland
A
  • Dilates;Constricts
  • Stop production;Increases production via medulla oblongata
  • Inotropic + chronotropic increase; decreases via vagus nerve
  • Dilates;Constricts via vagus nerve
  • Inhibits via solar plexus;Stimulates via vagus nerve
  • Stimulates glycogenolysis vua solar plexus;Stimulates glycogenesis and bile secretion
  • Inhibits contraction;Contracts
  • Stimulates adrenaline release via solar plexus

Tissues of the body (17 decks)

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