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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
Q

Astrocytes are often found around the initial segment and at the

A

Node of Ranvier

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26
Q

Astrocytes are linked by?

-permit passage of small ions

A

Gap Junctions

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27
Q

Can segregate one synapse from other synapses

A

Astrocytes

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28
Q

Astrocytes can accumulate neurotransmitters. This suggests that they must be partially responsible for

A

Terminating synaptic transmission

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29
Q

Have receptors present on astrocytes and can regulate astrocyte function

A

Neurotransmitters

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30
Q

Astrocytes project to

A

Capillaries

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31
Q

Factors released from astrocytes influence the formation of tight junctions between

A

Endothelial cells of capillaries

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32
Q

Influence the integrity of the blood brain barrier

A

Astrocytes

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33
Q

Factors released from astrocytes also regulate blood flow in the capillaries of the

A

Brain

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34
Q

Astrocytes also participate in the

A

Immune response

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35
Q

Divide and remove neuronal debris during injury

A

Astrocytes

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36
Q

The myelinating cells of the central nervous system

A

Oligodendrocytes

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37
Q

In the CNS, unmyelinated axons have no

A

Ensheathment

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38
Q

The myelin sheath produced by oligodendrocytes begins at the end of the

A

Initial segment

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39
Q

The myelin sheath produced by oligodendrocytes ends at the region of the

A

Axon terminal

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40
Q

The myelin sheath is interrupted at regular intervals by

A

noes of Ranvier

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41
Q

Segments of myelin between the nodes of ranvier are called

A

Internodal segments

42
Q

In human development, myelination begins at the

-accelerates in the last trimester

A

14th week of gestation

43
Q

Much of myelination occurs

-can last for several years

A

Postnatally

44
Q

Forms when the oligodendrocyte sends out processes which wrap axons in a spiral manner

A

Myelin

45
Q

Formed by the close apposition of the cytoplasmic faces of the plasma membrane when oligodendrocytes wrap axons

A

Dark major dense lines

46
Q

Represent apposed extracellular faces of the plasma membrane of adjoining wrappings

A

Lighter stained intraperiod lines

47
Q

Serves as an insulating coat of high resistance that isolates the axon from extracellular electrical influences

A

The myelin sheath formed by oligodendrocytes

48
Q

Areas near the Nodes of Ranvier where edges of the spirally wrapped lamellae are separated at the major dense lines

A

Paranodal regions

49
Q

Results in a series of tongue -like processes with oligodendrocyte cytoplasm

A

Paranodal regions

50
Q

Tongues of oligodendrocytes are closely associated with the axolemma at the

A

Paranodal regions

51
Q

At the paranodal regions, signals are thought to be transmitted between the

-Loss of these signals may result in MS or AD

A

Axon and oligodendrocyte

52
Q

Serves as an insulating coat of high resistance that isolates the axon from extracellular electrical influences

A

The Myelin sheath

53
Q

Bare regions of axon which are specialized for high capacitance and low electrical resistance

A

Nodes of Ranvier

54
Q

Nodes of Ranvier contain high levels of

A

Ion channels

55
Q

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

A

Spike threshold

56
Q

This results in the action potential jumping from node to node, which is called

A

Saltatory conduction

57
Q

Concentrations of sodium channels are found at the

A

Nodes of Ranvier

58
Q

Support cells in the peripheral nervous system (PNS) are known as

A

Schwann cells or satellite cells

59
Q

Associated with peripheral nerve fibers

A

Schwann cells

60
Q

Associated with cell bodies

A

Satellite cells

61
Q

Support cells in the PNS surround all peripheral neurons, regardless of whether they are

A

Myelinated or unmyelinated

62
Q

Produce growth factors and phagocytose debris at lesion cites

A

Schwann cells

63
Q

The most well understood function that Schwann cells exhibit is

A

Covering and myelinating peripheral neurons

64
Q

Cover all peripheral nerves

A

Schwann cells

65
Q

In the case of unmyelinated axons, one Schwann cell may be associated with as many as

A

20 unmyelinated axons

66
Q

Unlike in myelinated axons, Schwann cells covering unmyelinated axons do not contain any

A

Gaps

67
Q

In the PNS, even unmyelinated axons lie within the arms of

A

Schwann cells

68
Q

Unlike in the PNS, in the CNS, axons can be

A

Naked

69
Q

In the case of myelinated axons, one Schwann cell produces one internode associated with one

A

Axon

70
Q

In the CNS, one oligodendrocyte can form many

A

Internodes

71
Q

In the PNS, one Schwann cell can form

A

One internode

72
Q

When Schwann cells wrap an axon, inner leaflet opposition results in

A

Major dense lines

73
Q

When Schwann cells wrap an axon, outer leaflet adhesion results in

A

Intraperiod lines

74
Q

In the CNS, the adhering protein is a transmembrane protein called

A

PLP

75
Q

In the PNS, the adhering protein is a transmembrane glycoprotein called

A

Po

76
Q

Differences in the adhering proteins in the CNS and PNS may account for distinct

A

Demyelinating disease

77
Q

Modified dense fibrous connective tissue with

contractile cells that form a semipermeable barrier

A

Perineurium

78
Q

In the PNS, axons surrounded by Schwann Cells are surrounded by

-Not true for the CNS

A

CT coats and the endoneurium, perineurium, and epineurium

79
Q

One major difference between the CNS and PNS is that in the CNS, unmyelinated axons have no form of

A

Ensheathment

80
Q

In the PNS unmyelinated and myelinated axon are covered by Schwann cells that are covered by a

A

Basal lamina and connective tissue coats

81
Q

Nerve injury is serious since mature neurons can’t

A

Divide

82
Q

In the PNS, functional reconnections may form if the cell body is not

A

Damaged

83
Q

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

A

Peripheral nerves

84
Q

Line up on the remaining basal lamina and produce growth factors that “encourage” the sprouting processes to grow down the tubes

A

Schwann cells

85
Q

Regeneration of nerves in the PNS is more likely if the lesion is near the

A

Terminal (NOT the cell body)

86
Q

In the lesioned CNS, the nerve and its myelin sheath degenerate on both sides of the

A

Lesion site

87
Q

In the lesioned CNS, debris is removed by

A

Proliferating microglia and astrocytes

88
Q

Being used in some cases to enhance the regeneration of CNS neurons through their production of specific molecules

A

Glial Cells

89
Q

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

A

Connective tissue coats (endoneurium, etc) surrounding the neurons

90
Q

Another term for support cells is

A

Glial cells

91
Q

The place where capillaries are in close contact with ependymal cells and ependymal cells are altered so that they now have tight junctions

A

Choroid plexus

92
Q

Ependymal cells of the choroid plexus control what passes into the

A

Ventricle

93
Q

Regulate immune response in brain and also eliminate

nonviable neurons and glial cells

A

Microglial cells

94
Q

Lie between neurons and capillaries or between neurons and pia matter

A

Astrocytes

95
Q

Send processes from grey matter to white matter and help prevent spinal chord from collapsing

A

Astrocytes

96
Q

In a rapidly firing active synapse, astrocytes closely surround the synapse so that the neurotransmitter is efficiently moved from

A

One cell to another

97
Q

When a synapse is inactive, astrocytes

opens it’s arms so neurotransmitter can

A

Diffuse away

98
Q

Keep electron dense material from moving from one

compartment to another

A

Tight junctions in endothelial cells

99
Q

One oligodendrocyte can wrap

A

40-50 axons

100
Q

The area of a myelin sheet where the two ends overlap

A

Intraperiod line

101
Q

Protein that holds myelin sheets together in CNS

A

PLP

Structure and Function Test 1 (61 decks)

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