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1

3 classifications of neurons by shape include:

unipolar (pseudounipolar)
bipolar
multipolar

2

what are nissl bodies

-clumps of basophilic die in neuron soma on LM
-can be seen in H&E and multiple stains but most evident in nissl stain
-correspond to RER

3

this structure forms the "receiving end" of a neuron

dendrite

4

axodendritic synapse

synapse between axon & dendrite

5

presynaptic element

specialized for release of neurotransmitter

6

neurotransmitter is released from the __ element

presynaptic

7

postsynaptic element

contains membrane receptors to convert chemical signal into membrane potential

8

name 3 types of synapses based on anatomical location

axodendritic synapse (most common)
axosomatic synapse
asoaxonal synapse

9

axosomatic synapse

between axon & cell body

10

axoaxonal synapse

between axon and another axon

11

where does the presynaptic element occur?

terminal bouton - at end of axon
or
bouton en passant - if along length of axon

12

terminal bouton

presynaptic element at end of axon

13

bouton en passent

presynaptic element before the end of axon

14

where does the postsynaptic element Usually occur?

on the dendritic spine

15

where on the neuron is an action potential typically generated?

axon hillock

16

in a myelinated axon, spikes (APs) propagate via __ conduction

saltatory conduction

17

saltatory conduction

saltatory = "jumping"
the name for action potential propagation along nodes of ranvier in a myelnated axon

18

node of ranvier

naked axon node between myelinated internodes

19

T/F action potentials travel more slowly down unmyelinated axons

true
APs travel more quickly by saltatory conduction down myelinated axons

20

what is a myelin internode composed of?

wrapped cell plasma membrane
CNS - foot of an oligodendrocyte membrane
PNS - schwann cell membrane

21

how many myelin internodes can be formed by...
-a schwann cell?
-an oligodendrocyte?

schwann cell - one myelin internode in PNS
oligodendrocyte - multiple "feet" in CNS

22

how many myelin internodes can be formed by a schwann cell in the PNS?

one

23

how many myelin internodes can be formed by an oligodendrocyte in the CNS?

multiple

24

what is the difference between a schwann cell and an oligodendrocyte?

-schwann cells are located only in PNS, they form one myelin internode for a nearby axon and can support multiple unmyelinated axons which shoot through it like rods through dough
-oligodendrocytes are located only in CNS, they can form multiple myelin internodes on different axons with multiple projections or "feet" of its plasma membrane -- but they do not engulf unmyelinated axons like schwann cells in the PNS

25

are unmyelinated fibers more commonly found in the CNS or PNS?

they can be found in either, i think
PNS - small fibers for slow aches / pain / temp
CNS - maybe interneurons and other short neurons

26

on EM, myelin internodes can be seen as...

alternating major dense lines (apposed cytoplasmic membrane faces), and intraperiod lines (apposed ectoplasmic membrane faces)

27

major dense line

apposed protoplasmic schwann or oligodendrocyte cell membrane faces in a myelin internode on EM (alternates with intraperiod lines)

28

intraperiod line

apposed ectoplasmic schwann or oligodendrocyte cell membrane faces in a myelin internode on EM (alternates with major dense lines)

29

inner mesaxon

the tip of the myelin sheath that lies next to the axon

30

outer mesaxon

the tip of the myelin sheath that rests atop the last layer of myelin and the transition into schwann/oligodendrocyte cell body

31

T/F inner and outer mesaxons are both parts of the same process from the schwann/oligodendrocyte cell body

false
when wrapping an axon, the support cell extends two processes, one around either side of the axon in opposite directions (grabs it like a hand and rolls into a fist). the process that winds inward around the axon is the inner mesaxon (finger); the process that extends around the outside surface of the myelin sheath and rests on top is the outer mesaxon (thumb)

32

if a myelin sheath is like a fist around a pen, which mesaxon is the finger and which is the thumb?

inner mesaxon - finger
outer mesaxon - thumb

33

what is the general term for non-neuronal cells in nervous tissue?

glial cells
or
neuroglial cells

34

T/F glia is another term for neuroglial cells

true

35

what are the general functions of glial cells?

scaffolding
metabolic support
blood-brain barrier contributions

36

why are non-neruonal cells in nervous tissue called glial cells?

glia = glue
glial cells support neurons with scaffolding, metabolic support, etc (they do not literally stick neurons together)

37

name 5 neuroglial cells and their locations

astrocytes (CNS)
microglia (CNS)
oligodendrocytes (CNS)
schwann cells (PNS)
satellite cells (PNS)

38

astrocyte function

astrocytes are like the connective tissue of the CNS (which has no connective tissue)
-structure (glial fibrillary acidic protein)
-space filler
-stabilize ionic medium
-provide metabolic support
-proliferate and form scar in CNS damage

39

2 types of astrocytes

fibrous astrocyte (white matter)
protoplasmic astrocyte (grey matter)

40

fibrous astrocyte

astrocyte in white matter (axons)

41

protoplasmic astrocyte

astrocyte in grey matter (neuron soma)

42

this cell type takes up excess neurotransmitter and helps regulate the ion composition of the fluid around neurons

astrocyte

43

an astrocyte in white matter is called

fibrous astrocyte

44

an astrocyte in grey matter is called

protoplasmic astrocyte

45

microglial function

macrophage of the CNS
phagocytic cell patrolling brain and spinal cord

46

oligodendrocyte function

form multiple myelin internodes on CNS axons

47

this glial cell is part of the mononuclear phagocytic system MPS

microglia

48

where are microglia derived from?

from monocytes in bone marrow

49

the smallest type of neuroglial cell is the

microglia
(macrophage of the CNS)

50

macroglia include

all glial cells other than microglia
-astrocytes
-oligodendrocytes
-schwann cells
-satellite cells

51

schwann cell function

-form single myelin internode on PNS axon
-support unmyelinated axons like dough punched with rods

52

satellite cell function

encapsulate neuron soma in PNS ganglia
(usually multiple satellites per soma)
-protective cushion
-structural
-nutrient supply

53

how many satellite cells surround one neuron soma in a PNS ganglion?

usually multiple

53

how many satellite cells surround one neuron soma in a PNS ganglion?

usually multiple

54

T/F one satellite cell wraps around a neuron soma in a PNS galngion like a schwann cell wraps around an axon

false
multiple satellite splat on a soma to cover it, NOT just one wrapping around it

54

T/F one satellite cell wraps around a neuron soma in a PNS galngion like a schwann cell wraps around an axon

false
multiple satellite splat on a soma to cover it, NOT just one wrapping around it

55

this cell forms multiple myelin internodes in the CNS

oligodendrocyte

55

what is the unique intermediate filament in astrocytes?

GFAP glial fibrillary acidic protein
-useful for antibody staining

56

this cell in the PNS forms one myelin internode and can support multiple unmyelinated axons as well

schwann cell

56

this cell in the PNS forms one myelin internode and can support multiple unmyelinated axons as well

schwann cell

57

these cells cover a neuron soma in PNS ganglia, providing a cushion and nutrients

satellite cell

57

these cells cover a neuron soma in PNS ganglia, providing a cushion and nutrients

satellite cell

58

what is the unique intermediate filament in astrocytes?

GFAP glial fibrillary acidic protein
-useful for antibody staining

58

what is the unique intermediate filament in astrocytes?

GFAP glial fibrillary acidic protein
-useful for antibody staining

59

what characteristic of astrocytes can make them easily identifiable through antibody staining?

GFAPs
glial fibrillary acidic proteins
special intermediate filaments unique to astrocytes

59

what characteristic of astrocytes can make them easily identifiable through antibody staining?

GFAPs
glial fibrillary acidic proteins
special intermediate filaments unique to astrocytes

60

what is a GFAP?

glial fibrillary acidic proteins
special intermediate filaments unique to astrocytes

60

what is a GFAP?

glial fibrillary acidic proteins
special intermediate filaments unique to astrocytes

61

define ganglia

collections of neuron cell bodies outside the CNS (in the PNS)

61

define ganglia

collections of neuron cell bodies outside the CNS (in the PNS)

62

a discrete group of neuron soma in the CNS is called a __

nucleus
e.g. brainstem nucleus, paraventricular nucleus, etc

62

a discrete group of neuron soma in the CNS is called a __

nucleus
e.g. brainstem nucleus, paraventricular nucleus, etc

63

what is the synapse between motor neuron and muscle called?

neuromuscular junction

63

neuromuscular junction

synapse between motor neuron and muscle

64

the post-synaptic region of the plasmalemma of muscle is called the...

motor end plate

64

motor end plate

the post-synaptic region of the plasmalemma of muscle

65

is there a motor end plate on smooth muscle?

in rudimentary form
neuromuscular junction is most specialized in skeletal muscle

65

is there a motor end plate on cardiac muscle?

probably not so much... but possibly...
scarce innervation (autoelectrogenic)

66

neurophil

synaptically dense mesh of axons & dendrites
-most prominently in grey CNS matter
-but maybe possible in PNS ganglia?

66

neurophil

synaptically dense mesh of axons & dendrites
-most prominently in grey CNS matter
-but maybe possible in PNS ganglia?

67

3 meninges covering brain

dura mater (outer)
arachnoid mater (middle)
pia mater (inner)

67

3 meninges covering brain

dura mater (outer)
arachnoid mater (middle)
pia mater (inner)

68

this meninge of the brain is extremely tough

dura mater

68

this meninge of the brain is extremely tough

dura mater

69

what is the subarachnoid space?

space between arachnoid & pia mater usually filled with cerebral spinal fluid

69

what is the subarachnoid space?

space between arachnoid & pia mater usually filled with cerebral spinal fluid

70

this is a common site of brain hemorrhage

subarachnoid space
(space between arachnoid & pia mater usually filled with cerebral spinal fluid)

70

this is a common site of brain hemorrhage

subarachnoid space
(space between arachnoid & pia mater usually filled with cerebral spinal fluid)

71

2 classes of peripheral neurons

sensory
motor

71

2 classes of peripheral neurons

sensory
motor

72

these neurons control skeletal muscle

motor neurons

72

these neurons control skeletal muscle

motor neurons

73

what is the synapse between motor neuron and muscle called?

neuromuscular junction

73

what is the synapse between motor neuron and muscle called?

neuromuscular junction

74

neuromuscular junction

synapse between motor neuron and muscle

74

neuromuscular junction

synapse between motor neuron and muscle

75

the post-synaptic region of the plasmalemma of skeletal muscle is called the...

motor end plate

75

the post-synaptic region of the plasmalemma of skeletal muscle is called the...

motor end plate

76

motor end plate

the post-synaptic region of the plasmalemma of skeletal muscle

76

this nervous system has one long efferent nerve (no efferent ganglia)

somatic

77

is there a motor end plate on smooth muscle?

no
no motor neuron, no voluntary control, no motor endplate

77

is there a motor end plate on smooth muscle?

no
no motor neuron, no voluntary control, no motor endplate

78

is there a motor end plate on cardiac muscle?

no
no motor neuron, no voluntary control, no motor endplate

78

is there a motor end plate on cardiac muscle?

no
no motor neuron, no voluntary control, no motor endplate

79

how do motor neurons pass out of the spinal cord?

ventral root

79

pleomorphic vesicles indicate a __ synapse

inhibitory

80

what are the characteristics of a neuromuscular junction that can help you distinguish it from a nervous system synapse?

-folds in the muscle fiber membrane
-external lamina between may appear as a thin dark line between muscle plasma mebrane and axon plasma membrane
-maybe sarcomeres, actin, dense bodies

80

this neuron type passes out of the spinal cord through the ventral root

motor neuron

81

what kind of neurons exist in the ventral root

motor neurons

81

what kind of neurons exist in the ventral root

motor neurons

82

how do sensory neurons pass into the spinal cord?

through the dorsal root, after passing through the dorsal route ganglion

82

how do sensory neurons pass into the spinal cord?

through the dorsal root, after passing through the dorsal route ganglion

83

this neuron type passes into the spinal cord through the dorsal root

sensory neuron

83

this neuron type passes into the spinal cord through the dorsal root

sensory neuron

84

what kind of neurons exist in the dorsal root?

sensory neurons

84

what kind of neurons exist in the dorsal root?

sensory neurons

85

what is a motor neuron?

an efferent neuron that conducts signals from CNS to effectors (can be somatic or autonomic, sympathetic or parasympathetic, all have motor neurons)

85

what is a motor neuron?

an efferent neuron that conducts signals from CNS to effectors (can be somatic or autonomic, sympathetic or parasympathetic, all have motor neurons)

86

what is a sensory neuron?

an afferent neuron that conducts signals from periphery to CNS (can be somatic or autonomic, sympathetic or parasympathetic, all have sensory neurons)

86

what is a sensory neuron?

an afferent neuron that conducts signals from periphery to CNS (can be somatic or autonomic, sympathetic or parasympathetic, all have sensory neurons)

87

how is a motor neuron different from an efferent neuron?

i think they are basically the same thing...

87

how is a motor neuron different from an efferent neuron?

i think they are basically the same thing...

88

what organelles are found in dendrites?

microtubules
mitochondria
ER (in Large dendrites)
ribosomes (in Large dendrites)
neurofilaments (in Large dendrites)

89

on EM of a dendrite cross section, what are three circular structures that are likely to be observed?

from large to small:
mitochondria
microtubules
neurofilaments (in Large dendrites)
ER (in Large dendrites)
ribosomes (in Large dendrites)

90

what kind of cytoskeletal filaments are prevalent in dendrites?

microtubules (always prevalent)
neurofilaments (in Large dendrites)

91

which has larger cross sectional area, microtubules or neurofilaments? which is likely to be seen in a dendrite?

microtubules are larger
microtubules will always be seen, slightly larger
neurofilaments many be found in large dendrites

92

what is a dendritic spine?

small stickings out of the dendritic plasmalemma that each receive an axon terminal from another neuron
(look like running ink into little lateral short cracks along large crack that is dendrite on LM, or like a seismograph reading)

93

3 classes of connective tissue investments in the CNS

trick!
no connective tissue in the CNS
space is filled by astrocytes

94

T/F dendritic spines are dynamic and can move and grow

true

95

how many efferent neurons to conduct a parasympathetic motor signal?

2 - peripheral ganglia in or near effector organs / tissues

96

how many efferent neurons to conduct a sympathetic motor signal?

2 - paravertebral ganglia (sympathetic chain)

97

how many afferent neurons to conduct a sensory signal from any division of the nervous system

1 - pseudounipolar neurons with soma in the dorsal root ganglia

98

this nervous system has short preganglionic and long postganglionic efferent nerves

sympathetic

99

this nervous system has long preganglionic and short postganlionic efferent nerves

parasympathetic

100

this nervous system has one long efferent nerve (no efferent ganglia)

somatic

101

which membrane surface has more associated protein, protoplasmic or ectoplasmic?

protoplasmic

102

postsynaptic density

a histological term for postsynaptic element (appears as a density due to density of receptors)

103

how to tell an excitatory synapse from an inhibitory synapse on EM?

excitatory
-asymmetric: postsynaptic density is darker than presynaptic density
-vesicles are round
-narrower
inhibitory
-symmetric: pre and post synaptic densities are same density
-pleomorphic vesicles (altered shape)
-wider

104

a symmetric synapse is a __ synapse

inhibitory synapse
-pre and post synaptic densities are same density
-pleomorphic vesicles (altered shape)
-wider

105

an asymmetric synapse is a __ synapse

excitatory synapse
-postsynaptic density is darker than presynaptic density
-vesicles are round
-narrower

106

pleomorphic vesicles indicate a __ synapse

inhibitory

107

what are the characteristics of a neuromuscular junction that can help you distinguish it from a nervous system synapse?

a

108

how can you determine the location of a synaptic active site on EM?

the presynaptic vesicles may be queued / clustered at the synaptic sites, ready for release

109

what does a multipolar neuron look like on LM?

non-circular nucleus, can probably see multiple branches coming out before lost in surrounding tissue

110

T/F dendrites contain RER

~true
Large dendrites may have RER

111

is a neuron typically very actively transcribing or relatively quiescent?

actively transcribing
euchromatic
prominent nucleuolus

112

how large / small is a nueronal soma compared to surrounding glial cells?

very large
soma nucleus is larger than surrounding glia
soma nucleolus is about = surrounding glial nuclei

113

how do glial cells compare to neuron cell bodies in size?

they are much smaller
(just the somal nucleolus is ~ the size of surrounding glial cell nuclei)

114

what do nissl bodies look like on EM?

stacks of ER

115

golgi stain

stains only 1-5% of neurons (no one really knows why...) makes easier to visualize neuron and processes

116

if a stain illustrates just one neuron or only a few, what kind of stain is it probably?

golgi stain
stains only 1-5% of neurons (no one really knows why...) makes easier to visualize neuron and processes

117

the angle between branching dendrites is...

usually < 90 degrees

118

the angle in a branching axon is...

usually ~90 degrees

119

how do dendrites change with distance from cell body?

they taper off and end not too far away

120

what kind of glial cell is found in dorsal root ganglia?

satellite cell
subclass of schwann cell that splats onto pseudounipolar soma to protect / nourish
-found around all PNS soma / ganglia

121

where are satellite cells found?

in PNS ganglia splatting onto neuron soma

122

what do satellite cells look like on LM?

like a light staining layer with multiple peripheral nuclei around a neuron soma (round and unipolar (pseudounipolar) if in the dorsal root ganglia)

123

what do unipolar (pseudounipolar) neurons look like on LM?

mostly round soma, maybe one extension for axon if in right plane of section (multipolar were distorted by multiple processes)
-still have nissl bodies and large euchromatic nucleus with prominent nucleoulus
-surrounded by light layer of satellite cells

124

on EM of a dendrite cross section, what are three circular structures that are likely to be observed?

from large to small:
mitochondria
microtubules
neurofilaments

125

most of the nonstaining space between neuronal soma in a nissl stain is occupied by...

astrocytes ("connective tissue" of the CNS)
or perhaps oligodendrocytes (more associated with axons)

126

which has larger cross sectional area, microtubules or neurofilaments? which is likely to be seen in a dendrite?

microtubules are larger
both are likely to be seen, microtubules will be slightly larger

127

what is a dendritic spine?

small stickings out of the dendritic plasmalemma that each receive an axon terminal from another neuron
(look like running ink into little lateral short cracks along large crack that is dendrite on LM)

128

how can you tell an astrocyte from an oligodendrocyte on EM?

GFAP glial fibrillary acidic protein
appears like a dense cable of fibers in an astrocyte

129

this glial cell is very dynamic, moves through nervous tissue quickly, and is responsible for immune surveillance in the CNS

microglia

130

glial function in CNS:
-physical support
-control of microenvironment
-myelin synthesis
-defense / immune

astrocyte - physical support
astrocyte - control of microenvironment
oligodendrocyte - myelin synthesis
microglia - defense / immune

131

are there nissl bodies in axons and dendrites?

large dendrites maybe (may have R & RER)
axons no - no RER or free ribosomes

132

are there mitochondria in axons and dendrites on EM?

yes
higher conc in dendrites
stray mitochondria in axons

133

what organelles are likely to be seen in an axon transverse section

neurofilaments (smaller dots)
microtubules (larger, possibly tubular)
stray mitochondria
No RER or free ribosomes

134

what does a myelinated axon look like on transverse H&E?

eosinophilic cytoplasm
pale ring of myelin (lipid bilayer does not stain usually, though have seen it stain darker than axon in some slides)

135

what does a myelinated axon look like on osmium stain?

light axon
black myelin layer
(heavy metal stain, stains lipids dark)

136

what is the best way to tell a longitudinal section of a nerve from smooth muscle, tendon, or other connective tissue?

can spot nodes of ranvier
look like transverse lines

137

why do folds in myelin sometimes appear to come apart on EM?

schwann cell is opening a path for communication to axon

138

what do unmyelinated axons look like on EM?

may have microtubules & neurofilaments, possibly mitochondria, may be smaller next to myelinated axons, may be a cluster poking through schwann cell cytoplasm

139

what do unmyelinated axons look like on LM?

frothies near a dark schwann cell nucleus
each froth is smaller than a myelinated axon

140

what does a terminal bouton look like on golgi stain?

like a bleb at the end of an axon

141

glial function PNS CNS
phys support
microenvironment
myelin
defense/immune

glial function PNS CNS
phys support ct astro
microenvironment schw/sat astro
myelin schw oligo
defense/immune immun micro

142

what are the branches at the end of an axon called?

collaterals

143

what is an axospinous synapse?

axon to dendritic spine

144

T/F in rare cases, dendrites can have vesicles and pre presynaptic

true
in rare cases

145

T/F dendrites contain RER

~true
Large dendrites may have RER

146

multiple dendrites + axon = __ neuron

multipolar neuron

147

bipolar neuron

one input process (dendrite)
one output process (axon)
only found in retina & olfactory bulb

148

where are bipolar neurons found?

only retina and olfactory bulb

149

what kind of neuron is found in the retina?

bipolar neurons

150

what kind of neuron is found in the olfactory bulb?

bipolar neurons

151

what kind of neuron is found only in the retina and olfactory bulb?

bipolar neurons

152

where are unipolar (pseudounipolar) nuerons found?

only in the dorsal root ganglia
(sensory ganglia of the PNS)

153

this neuron is only found in the sensory ganglia of the PNS

unipolar (pseudounipolar)

154

what is the funciton of a unipolar (pseudounipolar) neuron?

allow fast conduction through dorsal root ganglion (sensory) while still maintaining a cell body for protein production and function

155

what kind of glial cell is found only in dorsal root ganglia?

satellite cell
subclass of schwann cell that splats onto pseudounipolar soma to protect / nourish

156

where are satellite cells found?

in dorsal root ganglia splatting onto pseudounipolar soma of sensory nerves

157

what do satellite cells look like on LM?

like a light staining layer with multiple peripheral nuclei around a round unipolar (pseudounipolar) neuron soma

158

what do unipolar (pseudounipolar) neurons look like on LM?

mostly round soma, maybe one extension for axon if in right plane of section (multipolar were distorted by multiple processes)
-still have nissl bodies and large euchromatic nucleus with prominent nucleoulus

159

T/F the size of a glial cell nucleus is ~ the size of a neuron nucleolus

true

160

most of the nonstaining space between neuronal soma in a nissl stain is occupied by...

astrocytes ("connective tissue" of the CNS)

161

what is a glial scar made up of?

astrocytes

162

what proportion of central nervous tissue is occupied by extracellular structures?

0%
no extracellular structures
spaces between neurons taken up by oligodendrocytes and astrocytes

163

how can you tell an astrocyte from an oligodendrocyte on EM?

GFAP glial fibrillary acidic protein
appears like a dense cable of fibers in an astrocyte

164

this glial cell is very dynamic, moves through nervous tissue quickly, and is responsible for immune surveillance in the CNS

microglia

165

glial function in CNS:
-physical support
-control of microenvironment
-myelin synthesis
-defense / immune

astrocyte - physical support
astrocyte - control of microenvironment
oligodendrocyte - myelin synthesis
microglia - defense / immune

166

dense connective tissue sheath around PNS nerves

epineurium

167

collagen fibers with squamous cells around PNS nerves

perineurium

168

type III collagen fibers between myelin sheaths in PNS

endoneurium

169

nervous tissue external lamina =

basal lamina surrounding schwann cells

171

what controls the microenvironment of neurons in the PNS?

schwann cells
satellite cells

172

how to tell if an EM is from CNS or PNS?

PNS will have the following; CNS will not
-collagen (clusters of transversely cut cables)
-external lamina (fuzziness) around schwann cell

173

silver stains...

reticular fibers
intracellular material of neurons
stroma

174

glial function in PNS:
physical support -
control of microenvironment -
myelin synthesis -
defense / immune -

physical support - connective tissue
control of microenvironment - schwann / sat
myelin synthesis - schwann
defense / immune - immune system

175

glial function PNS CNS
phys support
microenvironment
myelin
defense/immune

glial function PNS CNS
phys support ct astro
microenvironment schw/sat astro
myelin schw oligo
defense/immune immun micro

176

what is the series of events that occurs in the course of peripheral nerve regeneration

cut/trauma
local changes
retrograde reaction (chromotolysis)
antegrade reaction
distal axon & myelin phagocytosed
schwan cells proliferate distally
schwan tubes or bands of bungner
soma begins heightened production
proximal axon sprouts
grows into tubes
schwann cells remyelinate
guide to targer

177

why does peripheral nerve regeneration sometimes fail?

if sprouting axon cannot reach schwann cell tubes and it is unable to reach target, produces traumatic neuroma

178

what is a traumatic neuroma?

a painful tangle of axon that forms if a regenerating axon cannot reach distal schwann cell tube to complete regeneration

179

what is the consequence of failed peripheral nerve regeneration?

traumatic neuroma
a tangle of axon that forms if a regenerating axon cannot reach distal schwann cell tube to complete regeneration

180

chromatolysis

dissolution of nissl bodies in neuron soma in the event of nerve injury, perhaps nucleus moves to periphery
-nerve may undergo apoptosis
-if sufficient support from schwann cells and external membrane is present, peripheral nerve may regenerate after chromatolysis

181

how will the soma of a transected neuron compare to other intact neurons nearby?

soma loses nissl bodies (no need to send material down axon, chromatolysis)
-nucleus may move to periphery

182

is nerve regeneration possible in the CNS?

extremely rare
-no external lamina to guide axon sprouts
-central myelin inhibits axon growth in CNS
-astrocytes fill space with gliotic scar

204

what are the following connective tissue elements formed by?
-external lamina
-endoneurium
-perineurium
-epinuerium

external lamina - basal lamina of schwann cells (type IV collagen)
endoneurium - type III collagen fibers
perineurium - collagen fibers (III and IV) with squamous cells
epineurium - dense irregular connective tissue (type I collagen)

205

what are the following connective tissue elements formed by?
-external lamina
-endoneurium
-perineurium
-epineurium

external lamina - basal lamina of schwann cells (type IV collagen)
endoneurium - type III collagen fibers
perineurium - collagen fibers (III and IV) with squamous cells
epineurium - dense irregular connective tissue (type I collagen)

219

is nerve regeneration possible in the PNS?

yes it can be achieved, this is the process:
cut/trauma
local changes
retrograde reaction (chromotolysis)
antegrade reaction (wallerian reaction)
distal axon & myelin phagocytosed
schwan cells proliferate distally
schwan tubes or bands of bungner
soma begins heightened production
proximal axon sprouts
grows into tubes
schwann cells remyelinate
guide to targer

220

wallerian degeneration

the antegrade reaction in the distal part of a severed nerve... leads to distal axon and myelin being phagocytosed

221

after nerve injury:
retrograde reaction is called...
antegrade reaction is called...

chromatolysis
wallerian degeneration

222

the ventral root of the spinal cord is severed. where my you look to observe wallerian degeneration?

surface of striated muscle
(or at the presynaptic end of another motor synapse)

223

what kind collagen is found in endoneurium?

type III (reticular)

224

T/F type 1 collagen is found in endoneurium

false
type III collagen (reticular)

225

what collagen types exist in the following connective tissue layers in peripheral nervous tissue?
-external lamina
-endoneurium
-perineurium
-epineurium

external lamina - type IV
endoneurium - type III
perineurium - type III and type IV
epineurium - type I