CNS Flashcards
(90 cards)
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
2
Q
What are the 3 meninges laters?
A
- Dura Mater
- Arachnoid
- Pia Mater
3
Q
Thick layer of dense connective tissue, internally lined by ____?
A
mesothelium
4
Q
In cranium, fuses with___of skull
A
periosteum
5
Q
In spinal cord, dura is surrounded by what?
A
epidural space
6
Q
what is beneath the dura? what what does it separate?
A
subdural space; separates dura from underlying arachnoid mater
7
Q
subarachnoid space is lined by what?
A
lined by flattened mesothelial cells
8
Q
subarachnoid space
A
contains CSF & is continuous with ventricles of brain
9
Q
pia mater is ___ to surface of brain and cord?
A
adherent; it is highly vascular
10
Q
what makes up of leptomeninges?
A
pia + arachnoid
11
Q
Denticulate ligaments
A
support cord; extend from pia, anchor cord to arachnoid, dura & periosteum
12
Q
Neurons in CNS are derived from what?
A
neuroectodermal cells of neural tube
13
Q
what does the brain and cord contain?
A
gray and white matter
14
Q
peripheral gray matter
A
neuron cell bodies, dendrites & axons
15
Q
central white matter
A
contains mostly myelinated axon
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
17
Q
Types of neuroglia? (4)
A
- oligodendrocytes
- astrocytes
- microglia
- ependymal
18
Q
oligodendrocytes
A
CNS equivalent of Schwann cells; elaborate myelin sheaths
19
Q
astrocytes
A
- most highly branched; largest neuroglial cells
- Provide structural & metabolic support & aid in tissue repair following injury
20
Q
microglia
A
- phagocytic, fixed-tissue macrophages
- part of monocyte-macrophage lineage
- smallest neuroglial cells; originally mesodermal, have immune function
21
Q
ependymal cells
A
- Frequently ciliated; microvilli for reabsorbtion of CSF
- cuboidal epithelium lining ventricles & central canal of spinal cord
22
Q
what are the largest neuroglial cells?
A
astrocytes
23
Q
what are the smallest neuroglial cells
A
microglia
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
25
Cerebrum
=cerebral cortex
- composed of gray matter peripherally; contains large # of neuron cell bodies
-
26
neocortex
in mammals, evolved to include sensory, motor, and association areas
27
gyri
grossly organized folds
28
nuclei in cerebrum
clusters of neuron cell bodies form small islands of gray matter in cerebrum and cerebellum
29
in gray matter, neuroglial cells include what?
astrocytes and microglial cells
30
deep to cortex is____
subcortical white matter (=medulla)
31
white matter
Contains mostly myelinated axons surrounded by oligodendrocytes
32
tracts
axons leading in and out of gray matter is grouped in bundles
33
cortical neurons
* 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
34
types of cortical neurons (5)
1. pyramidal cells
2. stellate cells
3. cells of martinotti
4. fusiform cells
5. horizontal cells of cajal
35
pyramidal cells
- 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
36
Betz cells
upper motor neuron in motor cortex, associated with pyramidal cells
37
Stellate cells
=(granule)
| - small star-shaped neurons with short axons & dendrites
38
Cells of Martinotti
small neurons with long, horizontal axons
39
Fusiform cells
vertically oriented, spindle-shaped neurons with vertical axons
40
Horizontal cells of Cajal
horizontally oriented, spindle-shaped neurons with horizontal axons
- least common type of neuron, found only in superficial layer
41
what is the least common type of neuron & found only in superficial layer
horizontal cells of Cajal
42
what are the 6 layers of the neocortex?
```
I. Plexiform
II. Outer granular layer
III. pyramidal cell layer
IV. inner granular layer
V. ganglionic layer
VI. multiform cell layer
```
43
I. Plexiform
(molecular) layer—most superficial layer
| - contains mostly dendrites & axons of cortical neurons
44
II. outer granular layer
contains large #’s of small pyramidal & stellate cells
45
III. pyramidal cell layer
larger cells located deeper in layer; Martinotti cells also present
46
IV. inner granular layer
densely packed stellate cells
47
V. ganglionic layer
contains large pyramidal cells, stellate cells & cells of Martinotti
48
VI. multiform cell layer
contains small pyramidal cells, cells of martinotti, stellate cells and fusiform cells
49
Cerebellum
* Coordinates muscular activity, posture, & equilibrium
| * Grossly organized into folia, with central medulla of white matter
50
what are the 2 layers of the outer cerebellar cortex?
1. outer molecular layer
| 2. inner granular layer
51
outer molecular layer
contains few neurons & large #’s of unmyelinated axons
52
inner granular layer
-highly cellular, very basophiic -contains large # of neuroglial cells & granule cells
53
granules cells
small neurons
54
Purkinje cells
- Molecular & granular layers separated by single layer of large neurons
- specialized neurons, function in coordination & equilibrium
55
Spinal cord
Similar structure throughout; prominent ventral median fissure
56
central canal
contains CSF, lined by ependymal cells; continuous with ventricles of brain
57
In the spinal cord, gray matter is located____
centrally, white matter peripherally
58
In the spinal, gray matter contains___
neuron cell bodies & axons
59
central commissure
connected by 2 dorsal horns & 2 ventral horns
60
Dorsal horns contain
- afferent (sensory) N tracts
| - Cell bodies of somatic sensory neurons lie in dorsal root ganglia of spinal Nn
61
Dorsal N roots form...
lateral entensions of dorsal horns of gray matter
62
Ventral horns contain
efferent (motor) N cell bodies- innervate skeletal muscles
63
In spinal cord, surrounding white matter of cord contains:
ascending & descending fiber tracts (=columns)
| -mostly myelinated axons; carry sensory & motor data
64
In PNS, what forms a bridge between severed ends of nerve?
connective tissue scar and Schwann cells
65
What are the steps (3) if gap not too big, regeneration of axon possible (PNS)?
* 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
if damage too old or severe, axon may____
need to regrow its entire length, may take weeks to months
| PNS
67
Anterograde (Wallerian) degeneration
if portion of axon distal to point of injury degenerates
| PNS
68
when does nutrient synthesis occurs in cell body?
interruption of axonal transport
| PNS
69
chromatolysis
Cell body of an injured neuron also swells, becomes brightly eosinophilic, loses Nissl substance
(PNS)
70
retrograde degeneration
results if injury severe and death of cell body
| PNS
71
In CNS, oligodendrocytes are less efficient than___
Schwann cells; instead neuroglial cells multiply
72
Scar tissue proliferation from glial cells prevents what?
regeneration, physically blocks contact between cell body & axon (CNS)
73
When neurons terminally differentiated (Go)....
unable to be replaced (CNS)
74
ALS (amyotrophic lateral sclerosis)
= Lou Gehrig’s disease; also due to death of motor neurons controlling voluntary muscle
75
Meningitis
inflammation of meninges; may be bacterial or viral
76
Encephalitis
inflammation of brain
77
Myelitis
inflammation of spinal cord
78
encephalomyelitis
mixed involvement of brain and cord
79
meningoencephalitis
mixed involvement of meninges & brain
80
types of mixed involvement (2) and its symptoms?
encephalomyelitis & meningocephalits
| Symptons: vary from mild (headaches) to paralysis, debilitation & death
81
Viral meningitis generally
transient lymphocytic infiltrate
82
Bacterial meningitis
Meningococcus, Streptococcus) => neutrophilic infiltrate & may be life-threatening
83
Polio
poliovirus affects α-motor neurons of ventral horn of spinal cord => poliomyelitis
84
Polio results
- Lower motor neuron paralysis & subsequent Mm atrophy
| - Eradicated due to invention of Salk vaccine
85
Parkinson’sdisease
neurodegenerative disease characterized by muscular tremor due to death of neurons in substantia nigra
86
substantia nigra
-↓ production of dopaminein brain
-Tx involves administration of L-dopa, a dopamine precursor
(seen in parkinson's disease)
87
Alzheimer’s disease
form of dementia characterized by neural plaques & fibrillary tangles within cortex
88
Multiple sclerosis (MS)
* 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
Multiple sclerosis (MS) symptoms
- vary with location of affected neurons & degree of demyelination
- Often multiple episodes, with partial resolution in between
90
Guillain-Barre syndrome
* Immune-mediated demyelination in PNS
| * Often initiated by infection => progressive weakness in peripheral Mm
