CNS Flashcards

1
Q

Meninges

A
  • Singular meninx; composed of specialized epithelial cells (meningothelial cells)
  • Supported by connective tissue; have protective function
  • Confined to outer layer of brain & cord in CNS
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2
Q

What are the 3 meninges laters?

A
  1. Dura Mater
  2. Arachnoid
  3. Pia Mater
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3
Q

Thick layer of dense connective tissue, internally lined by ____?

A

mesothelium

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4
Q

In cranium, fuses with___of skull

A

periosteum

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5
Q

In spinal cord, dura is surrounded by what?

A

epidural space

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6
Q

what is beneath the dura? what what does it separate?

A

subdural space; separates dura from underlying arachnoid mater

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7
Q

subarachnoid space is lined by what?

A

lined by flattened mesothelial cells

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8
Q

subarachnoid space

A

contains CSF & is continuous with ventricles of brain

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9
Q

pia mater is ___ to surface of brain and cord?

A

adherent; it is highly vascular

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10
Q

what makes up of leptomeninges?

A

pia + arachnoid

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11
Q

Denticulate ligaments

A

support cord; extend from pia, anchor cord to arachnoid, dura & periosteum

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12
Q

Neurons in CNS are derived from what?

A

neuroectodermal cells of neural tube

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13
Q

what does the brain and cord contain?

A

gray and white matter

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14
Q

peripheral gray matter

A

neuron cell bodies, dendrites & axons

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15
Q

central white matter

A

contains mostly myelinated axon

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16
Q

what is neuroglia and its structure & function

A
  • Large # of support cells in CNS
  • Structure: Highly branched
  • Function: provide structural & metabolic support for neurons
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17
Q

Types of neuroglia? (4)

A
  1. oligodendrocytes
  2. astrocytes
  3. microglia
  4. ependymal
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18
Q

oligodendrocytes

A

CNS equivalent of Schwann cells; elaborate myelin sheaths

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19
Q

astrocytes

A
  • most highly branched; largest neuroglial cells

- Provide structural & metabolic support & aid in tissue repair following injury

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20
Q

microglia

A
  • phagocytic, fixed-tissue macrophages
  • part of monocyte-macrophage lineage
  • smallest neuroglial cells; originally mesodermal, have immune function
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21
Q

ependymal cells

A
  • Frequently ciliated; microvilli for reabsorbtion of CSF

- cuboidal epithelium lining ventricles & central canal of spinal cord

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22
Q

what are the largest neuroglial cells?

A

astrocytes

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23
Q

what are the smallest neuroglial cells

A

microglia

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24
Q

Choroid plexus

A
  • secretes CSF
  • vascular structure arising from walls of ventricle in brain
  • Contains modified ependymal cells
  • fluid acts like shock absorber
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25
Q

Cerebrum

A

=cerebral cortex
- composed of gray matter peripherally; contains large # of neuron cell bodies
-

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26
Q

neocortex

A

in mammals, evolved to include sensory, motor, and association areas

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27
Q

gyri

A

grossly organized folds

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28
Q

nuclei in cerebrum

A

clusters of neuron cell bodies form small islands of gray matter in cerebrum and cerebellum

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29
Q

in gray matter, neuroglial cells include what?

A

astrocytes and microglial cells

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30
Q

deep to cortex is____

A

subcortical white matter (=medulla)

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31
Q

white matter

A

Contains mostly myelinated axons surrounded by oligodendrocytes

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32
Q

tracts

A

axons leading in and out of gray matter is grouped in bundles

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33
Q

cortical neurons

A
  • Histologically, neurons of neocortex divided into five morphological categories
  • Anatomically, divided into six layers, designated with Roman numerals I-VI, from superficial to deep
  • Functionally, arranged in vertical columns or units
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34
Q

types of cortical neurons (5)

A
  1. pyramidal cells
  2. stellate cells
  3. cells of martinotti
  4. fusiform cells
  5. horizontal cells of cajal
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35
Q

pyramidal cells

A
  • Largest include upper motor neurons in motor cortex, known as Betz cells
  • pyramid-shaped neurons with long, slender axons, varying in size from small to large
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36
Q

Betz cells

A

upper motor neuron in motor cortex, associated with pyramidal cells

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37
Q

Stellate cells

A

=(granule)

- small star-shaped neurons with short axons & dendrites

38
Q

Cells of Martinotti

A

small neurons with long, horizontal axons

39
Q

Fusiform cells

A

vertically oriented, spindle-shaped neurons with vertical axons

40
Q

Horizontal cells of Cajal

A

horizontally oriented, spindle-shaped neurons with horizontal axons
- least common type of neuron, found only in superficial layer

41
Q

what is the least common type of neuron & found only in superficial layer

A

horizontal cells of Cajal

42
Q

what are the 6 layers of the neocortex?

A
I. Plexiform
II. Outer granular layer
III. pyramidal cell layer
IV. inner granular layer
V. ganglionic layer
VI. multiform cell layer
43
Q

I. Plexiform

A

(molecular) layer—most superficial layer

- contains mostly dendrites & axons of cortical neurons

44
Q

II. outer granular layer

A

contains large #’s of small pyramidal & stellate cells

45
Q

III. pyramidal cell layer

A

larger cells located deeper in layer; Martinotti cells also present

46
Q

IV. inner granular layer

A

densely packed stellate cells

47
Q

V. ganglionic layer

A

contains large pyramidal cells, stellate cells & cells of Martinotti

48
Q

VI. multiform cell layer

A

contains small pyramidal cells, cells of martinotti, stellate cells and fusiform cells

49
Q

Cerebellum

A
  • Coordinates muscular activity, posture, & equilibrium

* Grossly organized into folia, with central medulla of white matter

50
Q

what are the 2 layers of the outer cerebellar cortex?

A
  1. outer molecular layer

2. inner granular layer

51
Q

outer molecular layer

A

contains few neurons & large #’s of unmyelinated axons

52
Q

inner granular layer

A

-highly cellular, very basophiic -contains large # of neuroglial cells & granule cells

53
Q

granules cells

A

small neurons

54
Q

Purkinje cells

A
  • Molecular & granular layers separated by single layer of large neurons
  • specialized neurons, function in coordination & equilibrium
55
Q

Spinal cord

A

Similar structure throughout; prominent ventral median fissure

56
Q

central canal

A

contains CSF, lined by ependymal cells; continuous with ventricles of brain

57
Q

In the spinal cord, gray matter is located____

A

centrally, white matter peripherally

58
Q

In the spinal, gray matter contains___

A

neuron cell bodies & axons

59
Q

central commissure

A

connected by 2 dorsal horns & 2 ventral horns

60
Q

Dorsal horns contain

A
  • afferent (sensory) N tracts

- Cell bodies of somatic sensory neurons lie in dorsal root ganglia of spinal Nn

61
Q

Dorsal N roots form…

A

lateral entensions of dorsal horns of gray matter

62
Q

Ventral horns contain

A

efferent (motor) N cell bodies- innervate skeletal muscles

63
Q

In spinal cord, surrounding white matter of cord contains:

A

ascending & descending fiber tracts (=columns)

-mostly myelinated axons; carry sensory & motor data

64
Q

In PNS, what forms a bridge between severed ends of nerve?

A

connective tissue scar and Schwann cells

65
Q

What are the steps (3) if gap not too big, regeneration of axon possible (PNS)?

A
  • 1st step—Schwann cells multiply to physically bridge gap
  • 2nd step—nerve axon sprouts neurites from proximal stump
  • 3rd step—neurites grow into distal stump; contact reestablishes function
66
Q

if damage too old or severe, axon may____

A

need to regrow its entire length, may take weeks to months

PNS

67
Q

Anterograde (Wallerian) degeneration

A

if portion of axon distal to point of injury degenerates

PNS

68
Q

when does nutrient synthesis occurs in cell body?

A

interruption of axonal transport

PNS

69
Q

chromatolysis

A

Cell body of an injured neuron also swells, becomes brightly eosinophilic, loses Nissl substance
(PNS)

70
Q

retrograde degeneration

A

results if injury severe and death of cell body

PNS

71
Q

In CNS, oligodendrocytes are less efficient than___

A

Schwann cells; instead neuroglial cells multiply

72
Q

Scar tissue proliferation from glial cells prevents what?

A

regeneration, physically blocks contact between cell body & axon (CNS)

73
Q

When neurons terminally differentiated (Go)….

A

unable to be replaced (CNS)

74
Q

ALS (amyotrophic lateral sclerosis)

A

= Lou Gehrig’s disease; also due to death of motor neurons controlling voluntary muscle

75
Q

Meningitis

A

inflammation of meninges; may be bacterial or viral

76
Q

Encephalitis

A

inflammation of brain

77
Q

Myelitis

A

inflammation of spinal cord

78
Q

encephalomyelitis

A

mixed involvement of brain and cord

79
Q

meningoencephalitis

A

mixed involvement of meninges & brain

80
Q

types of mixed involvement (2) and its symptoms?

A

encephalomyelitis & meningocephalits

Symptons: vary from mild (headaches) to paralysis, debilitation & death

81
Q

Viral meningitis generally

A

transient lymphocytic infiltrate

82
Q

Bacterial meningitis

A

Meningococcus, Streptococcus) => neutrophilic infiltrate & may be life-threatening

83
Q

Polio

A

poliovirus affects α-motor neurons of ventral horn of spinal cord => poliomyelitis

84
Q

Polio results

A
  • Lower motor neuron paralysis & subsequent Mm atrophy

- Eradicated due to invention of Salk vaccine

85
Q

Parkinson’sdisease

A

neurodegenerative disease characterized by muscular tremor due to death of neurons in substantia nigra

86
Q

substantia nigra

A

-↓ production of dopaminein brain
-Tx involves administration of L-dopa, a dopamine precursor
(seen in parkinson’s disease)

87
Q

Alzheimer’s disease

A

form of dementia characterized by neural plaques & fibrillary tangles within cortex

88
Q

Multiple sclerosis (MS)

A
  • An autoimmune, inflammatory, demyelinating disease of CNS
  • Ab’s destroy myelin sheaths around axons => plaqueformation
  • Usually affects women between ages of 20-40 years old
89
Q

Multiple sclerosis (MS) symptoms

A
  • vary with location of affected neurons & degree of demyelination
  • Often multiple episodes, with partial resolution in between
90
Q

Guillain-Barre syndrome

A
  • Immune-mediated demyelination in PNS

* Often initiated by infection => progressive weakness in peripheral Mm