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Structure and Function Test 1 > Neurocytology II > Flashcards

Neurocytology II Flashcards

1
Q

The most numerous cells in the CNS and PNS

-outnumber neurons 3-10:1

A

Support cells

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2
Q

Most brain tumors, either benign or malignant, are

of

A

Glial origin

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3
Q

What are the four types of support (glial) cells in the central nervous system?

A

Ependymal cells, oligodendrocytes, astrocytes, and microglia

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4
Q

Gives rise to ependymal cells, oligodendrocytes, and astrocytes

A

Neuroepithelium

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5
Q

Thought to be of the macrophage-monocyte origin

-Do not come from the CNS

A

Microglia

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6
Q

Epithelial cells that line the ventricles of the brain and spinal canal of the spinal cord

-remnants of the original epithelium

A

Ependymal Cells

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7
Q

Line the central canal after neurons and other support cells have migrated away

A

Ependymal cells

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8
Q

Ependymal cells in most areas of the CNS are bound together by

A

Adhering (NOT occluding) junctions

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9
Q

Found in the ventricle or central canal and can enter and communicate with interstitial spaces of the CNS

A

Cerebrospinal fluid

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10
Q

In specific locations in the ventricle ependymal cells are modified to form the special secretory epithelium of the

A

Choroid plexus

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11
Q

What type of structure is the choroid plexus?

A

A vascular structure

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12
Q

The choroid plexus produces

A

Cerebrospinal fluid

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13
Q

Regulate transfer of cerebrospinal fluid

A

Ependymal cells

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14
Q

originate from outside neural tube and are members of the mononuclear phagocytic cell population

-are phagocytic

A

Microglia

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15
Q

Can eliminate nonviable neurons and glial cells in development

A

Microglil cells

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16
Q

In adults, microglial cells can eliminate

A

Inactive synapses

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17
Q

In areas of neural damage, microglial cells can eliminate

A

Dying cells

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18
Q

Produce molecules associated with the immune
system that can recruit leukocytes across the blood brain barrier to interact with astrocytes and modulate immune function

A

Microglial cells

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19
Q

Star shaped support cells

A

Astrocytes

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20
Q

The most distinct organelles that astrocytes have are glial filaments (intermediate filaments) made of

-allows astrocytes to be studied in vivo and in a culture dish

A

Glial fibrillary acidic protein (GFAP)

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21
Q

Often lie between neurons and capillaries and send processes to the basal lamina of the capillary

A

Astrocytes

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22
Q

May lie at the interface of neuron and pia mater and send processes to the basal lamina in contact with the pia

A

Astrocytes

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23
Q

Provide structural support for the nervous system

A

Astrocytes

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24
Q

Astrocytes may regulate the ionic environment by serving as

A

K+ sinks

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25
Astrocytes are often found around the initial segment and at the
Node of Ranvier
26
Astrocytes are linked by? -permit passage of small ions
Gap Junctions
27
Can segregate one synapse from other synapses
Astrocytes
28
Astrocytes can accumulate neurotransmitters. This suggests that they must be partially responsible for
Terminating synaptic transmission
29
Have receptors present on astrocytes and can regulate astrocyte function
Neurotransmitters
30
Astrocytes project to
Capillaries
31
Factors released from astrocytes influence the formation of tight junctions between
Endothelial cells of capillaries
32
Influence the integrity of the blood brain barrier
Astrocytes
33
Factors released from astrocytes also regulate blood flow in the capillaries of the
Brain
34
Astrocytes also participate in the
Immune response
35
Divide and remove neuronal debris during injury
Astrocytes
36
The myelinating cells of the central nervous system
Oligodendrocytes
37
In the CNS, unmyelinated axons have no
Ensheathment
38
The myelin sheath produced by oligodendrocytes begins at the end of the
Initial segment
39
The myelin sheath produced by oligodendrocytes ends at the region of the
Axon terminal
40
The myelin sheath is interrupted at regular intervals by
noes of Ranvier
41
Segments of myelin between the nodes of ranvier are called
Internodal segments
42
In human development, myelination begins at the -accelerates in the last trimester
14th week of gestation
43
Much of myelination occurs -can last for several years
Postnatally
44
Forms when the oligodendrocyte sends out processes which wrap axons in a spiral manner
Myelin
45
Formed by the close apposition of the cytoplasmic faces of the plasma membrane when oligodendrocytes wrap axons
Dark major dense lines
46
Represent apposed extracellular faces of the plasma membrane of adjoining wrappings
Lighter stained intraperiod lines
47
Serves as an insulating coat of high resistance that isolates the axon from extracellular electrical influences
The myelin sheath formed by oligodendrocytes
48
Areas near the Nodes of Ranvier where edges of the spirally wrapped lamellae are separated at the major dense lines
Paranodal regions
49
Results in a series of tongue -like processes with oligodendrocyte cytoplasm
Paranodal regions
50
Tongues of oligodendrocytes are closely associated with the axolemma at the
Paranodal regions
51
At the paranodal regions, signals are thought to be transmitted between the -Loss of these signals may result in MS or AD
Axon and oligodendrocyte
52
Serves as an insulating coat of high resistance that isolates the axon from extracellular electrical influences
The Myelin sheath
53
Bare regions of axon which are specialized for high capacitance and low electrical resistance
Nodes of Ranvier
54
Nodes of Ranvier contain high levels of
Ion channels
55
During the passage of an action potential down the axon, as each node becomes active, an inward ionic current flows down the axon core to depolarize the next node and bring it to
Spike threshold
56
This results in the action potential jumping from node to node, which is called
Saltatory conduction
57
Concentrations of sodium channels are found at the
Nodes of Ranvier
58
Support cells in the peripheral nervous system (PNS) are known as
Schwann cells or satellite cells
59
Associated with peripheral nerve fibers
Schwann cells
60
Associated with cell bodies
Satellite cells
61
Support cells in the PNS surround all peripheral neurons, regardless of whether they are
Myelinated or unmyelinated
62
Produce growth factors and phagocytose debris at lesion cites
Schwann cells
63
The most well understood function that Schwann cells exhibit is
Covering and myelinating peripheral neurons
64
Cover all peripheral nerves
Schwann cells
65
In the case of unmyelinated axons, one Schwann cell may be associated with as many as
20 unmyelinated axons
66
Unlike in myelinated axons, Schwann cells covering unmyelinated axons do not contain any
Gaps
67
In the PNS, even unmyelinated axons lie within the arms of
Schwann cells
68
Unlike in the PNS, in the CNS, axons can be
Naked
69
In the case of myelinated axons, one Schwann cell produces one internode associated with one
Axon
70
In the CNS, one oligodendrocyte can form many
Internodes
71
In the PNS, one Schwann cell can form
One internode
72
When Schwann cells wrap an axon, inner leaflet opposition results in
Major dense lines
73
When Schwann cells wrap an axon, outer leaflet adhesion results in
Intraperiod lines
74
In the CNS, the adhering protein is a transmembrane protein called
PLP
75
In the PNS, the adhering protein is a transmembrane glycoprotein called
Po
76
Differences in the adhering proteins in the CNS and PNS may account for distinct
Demyelinating disease
77
Modified dense fibrous connective tissue with | contractile cells that form a semipermeable barrier
Perineurium
78
In the PNS, axons surrounded by Schwann Cells are surrounded by -Not true for the CNS
CT coats and the endoneurium, perineurium, and epineurium
79
One major difference between the CNS and PNS is that in the CNS, unmyelinated axons have no form of
Ensheathment
80
In the PNS unmyelinated and myelinated axon are covered by Schwann cells that are covered by a
Basal lamina and connective tissue coats
81
Nerve injury is serious since mature neurons can't
Divide
82
In the PNS, functional reconnections may form if the cell body is not
Damaged
83
May regrow along the tubes formed by the basal lamina, endoneurium, perineurium, and epineurium following axonal degredation as long as these structures are in tact
Peripheral nerves
84
Line up on the remaining basal lamina and produce growth factors that “encourage” the sprouting processes to grow down the tubes
Schwann cells
85
Regeneration of nerves in the PNS is more likely if the lesion is near the
Terminal (NOT the cell body)
86
In the lesioned CNS, the nerve and its myelin sheath degenerate on both sides of the
Lesion site
87
In the lesioned CNS, debris is removed by
Proliferating microglia and astrocytes
88
Being used in some cases to enhance the regeneration of CNS neurons through their production of specific molecules
Glial Cells
89
Differences in the ability of CNS and PNS neurons to regenerate may depend, at least in part, on the arrangement of the glial cells and the presence or not of
Connective tissue coats (endoneurium, etc) surrounding the neurons
90
Another term for support cells is
Glial cells
91
The place where capillaries are in close contact with ependymal cells and ependymal cells are altered so that they now have tight junctions
Choroid plexus
92
Ependymal cells of the choroid plexus control what passes into the
Ventricle
93
Regulate immune response in brain and also eliminate | nonviable neurons and glial cells
Microglial cells
94
Lie between neurons and capillaries or between neurons and pia matter
Astrocytes
95
Send processes from grey matter to white matter and help prevent spinal chord from collapsing
Astrocytes
96
In a rapidly firing active synapse, astrocytes closely surround the synapse so that the neurotransmitter is efficiently moved from
One cell to another
97
When a synapse is inactive, astrocytes | opens it's arms so neurotransmitter can
Diffuse away
98
Keep electron dense material from moving from one | compartment to another
Tight junctions in endothelial cells
99
One oligodendrocyte can wrap
40-50 axons
100
The area of a myelin sheet where the two ends overlap
Intraperiod line
101
Protein that holds myelin sheets together in CNS
PLP

Structure and Function Test 1 (61 decks)

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