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Unit 2-embryology and histology of nervous system Flashcards

1
Q

What structures are apparent at week 4 of embryological development?

A

Neural crest and tube

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2
Q

What do the neural crest and tube become?

A

The spinal cord and 3 primary brain vesicles (which has two flexures: cervical and cephalic)

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3
Q

What are the 3 primary brain vesicles?

A

The prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain)

these 3 vesicles are primary vesicles

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4
Q

During weeks 5-6 what does the prosencephalon develop into?

A

the telencephalon and diencephalon

secondary vesicles

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5
Q

what structures come from the telencephalon?

A

cerebral cortex, basal ganglia, and lateral ventricles

secondary vesicles

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6
Q

what structures come from the diencephalon?

A

thalamus, hypothalamus, pineal gland, and 3rd ventricle

secondary vesicles

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7
Q

During weeks 5-6 what does the mesencephalon develop into?

A

corpora quadrigemina (tectum), cerebral peduncles, and cerebral aqueduct

secondary vesicles

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8
Q

during weeks 5-6 what does the rhombencephalon develop into?

A

the metencephalon and myelencephalon

secondary vesicles

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9
Q

what structures come from the metencephalon?

A

cerebellum, pons, and 4th ventricle

secondary vesicles

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10
Q

what structures come from the myelencephalon?

A

M.O., and 4th ventricle which is continuous with the spinal cord

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11
Q

The brain at birth equals what percentage of body weight and uses how much O2?

A

10% and uses 50-60% of O2

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12
Q

As an adult the brain equals what percentage of body weight and uses how much O2?

A

2-5% and uses 20% of O2

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13
Q

Within 1st year how much in size does the brain grow?

A

it doubles it size and more then 1/2 of brain growth occurs during this time period

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14
Q

The CNS arises from what structure in general?

A

the neural tube

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15
Q

The PNS arises from what structs in general?

A

the neural crest cells

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16
Q

Neuroepithelial cells give rise to what structes?

A

Neuroblasts, ependymal cells, and glioblasts

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17
Q

Neuroblasts give rise to what?

A

neurons

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18
Q

Glioblasts give rise to what?

A

astrocytes and oligodendrocytes

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19
Q

Gliobasts are synonymous with what and can undergo what?

A

nerve glue

they can undergo mitosis

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20
Q

What are some functions of glioblasts?

A

their derivations are the FUNCTIONAL connective tissue of the CNS and help guide neurons to their positions in early development

there are 5-10x as many glioblast derivatives as there are neurons

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21
Q

Astrocytes characterisitcs

A

most numerous cell in adult nervous sytem’

have mobility potential

little evidence to suggest they divided in mature brain

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22
Q

Protoplasmic astrocytes are found where?

A

in gray matter

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23
Q

Fibrous astrocytes are found where?

A

in white matter

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24
Q

Functions of astrocytes

A

structural support cells

found between blood vessel capillaries and neuron cell bodies as part of the BBB

stores what little glucose can be stored in the nervous system

forms “scar-like” tissue in CNS after injury

neurotransmitters like dopamine, glutamate, and serotonin may be influenced by astrocytes at synatpic gaps

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25
Oligodendrocyte characteristics
fewer in number than astrocytes and mainly forms myelin sheaths
26
Perineuronal satellites (type of oligodendrocyte)
found in gray matter and has possible nutritional role
27
Interfasicular (type of oligodendrocyte)
found in white matter and forms myelin in CNS
28
Characteristics of ependymal cells
line the central canal and ventricles serve as leaky barrier between CSF and CNS parenchyma classified as simple cuboidal but some are adapted taller cells and with microvilli and are present in ventricles secretes CSF from choroid plexus in each ventricle
29
found in 3rd ventricle and transports CSF to hypophyseal portal system
tanycytes
30
most common primary brain tumor
astrocytoma
31
most lethal brain tumor and is more likely to occur as one is older
glioblastoma
32
derived from ependymal cells and dysfunctions CSF which accumulates CSF in brain
ependyoma
33
Microglio characteristics
Mesodermally derived and arise from fetal macrophages which sequester into blood stream during development while resting they have numerous tiny processes they become activated after neural tissue is injured and become phagocytic, clearing damaged or dead tissue mediates CNS immune responses only neural cells affected by HIV
34
Neuralblast chracterictics
neuroepithelial origins near neural tube show little mitotic ability depend glial cells to guide them as they move through CNS radiation or alcohol exposure during development may cause them over/under shoot their destination
35
(pseudo)unipolar neuron
most common; found in DRG or spinal ganglion really two neurons wrapped together to look like one primarily used for sensory function and found in PNS as afferent neuron
36
bipolar neuron
found dominately in special sense organs such as retina, inner ear, and nasal cavity
37
multipolar neuron
has only one axon but many dendrites and branches is the vast majority of neurons in CNS and is most numerous carries motor information
38
Golgi type I (multipolar)
has a long axon maybe 1M or longer
39
Golgi type II (multipolar)
short axons and more numerous than golgi type I
40
sensory neruon
afferent runs from PNS to CNS neural crest derivative
41
motor neruon
efferent runs from CNS to PNS neural tube derivative
42
Internuncial neuron
only in CNS messengers or connectors between incoming sensory info and outgoing motor associative or interneuron are interchangeable with internuncial
43
commissural neuron
neuron that runs between equal structures on opposite sides of CNS Ex. Lt. central gyrus to Rt. central gyrus
44
Projection neuron
type of internuncial that runs from one structure in the CNS and ends in another struture Ex. Rt. cerebrum to Lt. midbrain
45
Ipsilateral
runs on the same side
46
Contralateral
runs on opposite side
47
Intra segmental
begins and ends in the same cord level
48
inter segmental
begins in one cord level and ends in another
49
Cell body (some, or perikaryon)
contains the nucleus of a neuron
50
Axon hillock
gradually boundary between the axon and cell body this is where nerve or action potentials are initiated
51
Axolemma
outer plasma membrane of neuron
52
Typical diameter of a perikaryon?
4-130 microns, the bigger the perikaryon the faster a nerve impulse travels
53
The shapes of a perikaryon?
stellate, fusiform, oval, round, and pyramidal
54
how long can a process be?
from just a few microns up to 40 inches
55
Axoaxonic
least common form of a synapse the end of an axon from one neuron synapses onto the axon of another neuron
56
axodendritic
most common form of a synapse the axon of one neuron synapses onto the dendrite of another neuron
57
axosomatic
the axon of one neuron synapses onto the cell body of another neuron
58
organelle that is considered the powerhouse is most concentrated where in the cell and produces what compound?
the mitochondria and is concentrated in the cell body and telodendria due to high levels of activity the mtiochondria produces ATP
59
the golgi apparatus houses what processes?
retispersion and chromatolysis
60
retispersion is the process of what?
fragmentation of the golgi apparatus
61
chromatolysis is the process of what?
Nissl bodies are dispersed after neuronal injury
62
what are nissl bodies and what other name do they go by?
clumps of RER and free ribosomes plus iron deposits they are also called tigroid bodies nissl bodies only appear in large neurons and are only found in the cell body and dendrites of neurons
63
centrosome organelle
likely the remnants of when it was capable of mitosis
64
Are neurofibrils real?
yes they are
65
List the three types of microfibrils
microtubules microfilaments neurofilaments
66
What is the function of microtubules and their size?
They help maintain cell shape and are 20-30nm in diameter
67
What is the function of microfilaments and their size?
they run longitudinally and circumferentially and associate with axolemma. theyre 3-5nm is diameter
68
How big are neurofilaments?
9-10 nm in diameter
69
Describe axoplasmic transport
it is the movement of raw materials within a cell
70
Describe slow transport in a cell
its the movement of materials like protein for neurofibrils and mitochondira within a cell moves about .1-3 mm/day in the anterograde direction speed of flow depends on axon length; the longer the faster; also needs little energy
71
Describe fast transport
is the movement of synaptic vessicles,lysosomes, and enzymes moves 100-400 mm/day anterograde or retrograde speed of transport not dependent on axon length but needs energy
72
What is the myelin covering in the CNS?
intrafasicular oligodendrocytes
73
What is the composition of myelin?
phospholipid/cholesterol and neurokeratin
74
Is myelin made by the neuron?
No its made by a surrounding cell
75
What forms the myelin in the PNS?
Schwaan cells
76
What part of the neuron does myelin only cover?
the long axon process
77
How long must a neuron fiber be for myelin to form on it?
at least one micron in length
78
If the neuron fiber is thicker, in general whats the diameter of the myelin?
its thicker as well
79
Is a nerve impulse faster if the myelin is thicker or thinner?
if the myelin is thicker
80
What two things determine conduction velocity?
fiber diameter and myelin
81
What would be an example of a PNS nerve fiber that has a schaan cell but is not myelinated?
post ganglion sympathetic neurons
82
What is it called when one schwaan cell in the PNS meets another schwaan cell?
node of ranvier
83
What is an internode?
the length of a schwaan cell covering
84
How long can an internode be?
50-750 microns
85
Do all nerve fibers have a neurilemma?
yes
86
Describe endoneurium
highly vascular, fibrous and cellular matrix covering neurilemma. continues onto telodendritic branches
87
Describe perineurium
it wraps around groups of fibers it is the most elastic of coverings its continuous with the pia and arachnoid as it gets close to CNS structures
88
Describe epineurium
outer coat of a nerve inelastic, gives protection, strength and support to fibers. is continuous with dura as it gets close to CNS structures
89
Are nodes of ranvier in the CNS?
yes but are oligodendrocytes instead
90
How many cells can an oligodendrocyte cover?
up to 40

CNS (7 decks)

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