Cellular Elements Of The Nervous System & Reaction To Injury

Front 1

What are the cellular elements of the immature nervous system?

Back 1

primitive, pluripotent neuroectodermal cells (germinal matrix)

Front 2

Embryonal Tumors correspond to what cells?

Back 2

primitive germinal matrix cells

Front 3

What are the cellular elements of the mature nervous system?

Back 3

Neurons

Glia: astrocytes, oligodendrocytes, microglia

Ependymal Cells

Front 4

The large area of central white matter subjacent to the cortex is:

Back 4

Centrum Semiovale

Front 5

What is the "first cellular element of the nervous system"?

Back 5

Neuron

Front 6

Neurons of the laminated cerebral cortex are frequently ___________ or ___________ in configuration and are _______________ with the apex pointing up toward the surface of the brain and the base facing downward toward the subjacent white matter.

Back 6

Triangular
Pyramidal
Polarized

Front 7

The myelinated axon arises from the (base/apex) to enter the subjacent white matter or centrum semiovale.

Back 7

Base

Front 8

Intractable seizure disorder characterized by total disarray of cortical neurons including loss of lamination and polarization, resulting in a jumbled, disorderly pattern.

Back 8

Cortical Dysplasia

Front 9

What is the size range of neurons?

Back 9

50-90 microns

90 microns: Betz cell of the motor cortex

Front 10

The nucleus of a neuron is clear, round, vesicular or clear and contains a prominent ____________.

Back 10

Nucleolus

Front 11

Neurons have abundant cytoplasm containing dark blue _________ _________.

Back 11

Nissl material

Front 12

The Nissl material is distributed in coarse clumps within _________ neurons (called ________ _________) and distributed evenly in the cytoplasm of _________ neurons (called ________ ________).

Back 12

motor (Nissl bodies)
sensory (Nissl substance)

Front 13

What stain makes the elongated cytoplasmic processes of neurons visible?

Back 13

heavy metal stains

Front 14

Axon represents the _______ limb of the neurons whereas the _________ represent the ________ limb of the neuron.

Back 14

Efferent

Afferent

Front 15

What is the interneuronal point of contact called?

Back 15

Synapse

Front 16

____________ refers to the sum total of positive pre-synaptic impulses converging on a secondary or tertiary neuron from other primary neuronal sources, promoting discharge of an electrical impulse

Back 16

Facilitation

Front 17

___________ refers to the sum of total negative presynaptic impulses converging on a secondary or tertiary order neuron from other primary neuronal sources, preventing discharge or firing.

Back 17

Inhibition

Front 18

_________ refers to the sum of total pre-synaptic positive and negative impulses converging on a secondary or tertiary order neuron.

Back 18

Summation

Front 19

What is the Final Common Pathway?

Back 19

The convergence of several facilitating and inhibiting pre-synaptic impulses from multiple neuronal sources upon a secondary or tertiary order neuron, determining whether or not the neuron will fire.

Front 20

The axons and dendrites are ___________ with each other and with the cell bodies of other neurons (distinct and separate entities)

Back 20

contiguous

Front 21

Acute Neuronal Injury represents a variant of __________ necrosis.

Back 21

coagulation

*reflects irreversible injury

Front 22

What characterizes Acute Neuronal Injury? What is a common cause? When is it visible w/ light microscopy?

Back 22

shrinkage (pyknosis) of the neuron

hypoxic-ischemic injury

12 or more hours post-insult

Front 23

What are features of a neuron undergoing Acute Neuronal Injury (Dead-Red Neuron)?

Back 23

Pyknosis of entire cell
Brick-red discoloration of cytoplasm
Nucleus shrinks
Neuron does not regenerate

Front 24

_____________ is engulfing and ingesting the dead-red neuron by macophages.

Back 24

Neuronophagia

Front 25

Neuronophagia is also referred to as:

Back 25

glial nodule

*term of reference for neuronal death due to viral or Rickettsial infections

Front 26

Injury to the CNS of a fetus or infant results in ______________ where the dead neurons are not removed by the immature phagocytes, but become coated with a mixture of calcium, protein, and iron.

Back 26

mineralization, ferruginization, mummification

Front 27

Where can the earliest evidence of Dead-Red Neurons be observed, particularly in cases of hypoxic-ischemic injury?

Back 27

Border Zones or Watershed Areas

Front 28

What do the Border Zones represent?

Back 28

terminal/distal supply areas of the major cerebral arteries

Front 29

What are the three important Border Zone areas?

Back 29

Parasaggital region of the cortex--one inch lateral to the sagittal fissure representing the border zone between the anterior and middle cerebral arteries

Hippocampal region of the temporal lobe--representing the border zone between the middle and posterior cerebral arteries.

*CA1 of Ammon's Horn is exquisitely sensitive

Equator of cerebellar convexity--representing the Border Zone between the superior and inferior cerebellar arteries

Front 30

___________ implies that the border zone neurons are characterized by an inherent susceptibility to injury, based on intrinsic physiological, chemical or molecular differences.

Back 30

Pathoclisis

*other explanations include anatomic differences such as the terminal arterial supply of the border zones

Front 31

The _________________ and ________________are characterized by swelling of neurons and are potentially reversible.

Back 31

Axonal Reaction

Trans-synaptic degeneration

Front 32

What represents a retrograde response of the neuron due to injury of the axon proximate to the cell body of the neuron of origin?

Back 32

Axonal Reaction

Front 33

What are features of the Axonal Reaction?

Back 33

Primary or First Order neuron of origin of the damaged axons swells

Loss of Nissl material prominent in the central area of the cytoplasm (Central Chromatolysis)

Nissl material migrates to edge of nucleus

The entire cell resembles a "Fish Eye"

Front 34

What is the reaction of a second order neuron to injury of an axon from a first order neuron called?

Back 34

Trans-synaptic degeneration

*second order neuron swells*

Front 35

What is Hypertrophy of the Olive?

Back 35

When enough pre-synaptic, descending axons are injured, the entire Inferior Olivary Nucleus may swell, resulting in diffuse enlargement of the entire structure.

Front 36

Yellow-tan intracytoplasmic neuronal pigment which increased with age. Thought to represent a benign "wear-and-tear" phenomenon.

Back 36

Lipofuscin

Front 37

Normal intracytoplasmic neuronal pigment found in specific nuclei such as the Substantia Nigra, Locus Coeruleus, Dorsal Motor X.

Back 37

Neuromelanin

*present in albinos

Front 38

The melanin content of the ___________________ parallels the melanin content of the skin.

Back 38

Leptomeninges (pia & arachnoid)

Front 39

Neuromelanin is lost w/ gross depigmentation of the pigmented nuclei in ______________ due to degeneration of the neurons containing neuromelanin.

Back 39

Parkinson's Disease

Front 40

What are examples of intracytoplasmic inclusions associated with degenerative diseases?

Back 40

Neurofibrillary Tangles (Alzheimer's)
Pick Bodies (Pick's Disease)
Lewy Bodies (Parkinson's Disease)

Front 41

What is an example of intracytoplasmic inclusions associated with viral diseases?

Back 41

Negri Bodies (Rabies)

Front 42

What are large, reddish-purple, intranuclear inclusions which displace the chromatin to the nuclear margin?

Back 42

Cowdry Type A Intranuclear Inclusions

Front 43

What viral diseases can show Cowdry Type A Intranuclear Inclusions?

Back 43

"CHiPS"

Cytomegalic Disease
Herpes Simplex & Zoster
PML (JC Virus)
Subacute Sclerosing Encephalitis (Dawsons and Measles Virus)

Front 44

_________________ designates neoplasms containing neurons

Back 44

Ganglion Cell Tumor

Front 45

The ______________, with its delicate, interdigitated cytoplasmic processes glues the CNS together and forms the _________.

Back 45

Astrocyte

Neuropil

Front 46

The Astrocyte, representing the second cellular element of the nervous system is of _______________ origin.

Back 46

Neuroectodermal

Front 47

What are the cellular characteristics of an Astrocyte?

Back 47

small, round nucleus & a salt-and-pepper chromatin pattern with the H&E stain

Front 48

The __________ stain, illustrates an abundance of delicate cytoplasmic processes radiating from the cell body.

Back 48

GFAP

*Glial Fibrillary Acid Protein

Front 49

The delicate cytoplasmic processes of Astrocytes interdigitate to form a delicate _____________ in which neurons are embedded, much like raisins in a loaf of bread.

Back 49

finely fibrillar Neuropil

Front 50

_____________ Astrocytes, located in the gray matter, are characterized by a plump cell body and thick cytoplasmic processes.

Back 50

Protoplasmic

Front 51

_____________ Astrocytes, situated in the white matter, have spindled cell bodies and thin delicate cytoplasmic processes.

Back 51

Fibrillary

Front 52

_____________ indicates the non-specific response of Astrocytes to injury of any kind, resulting in swelling & visibility of the cytoplasm with H&E, which assumes a pinkish-red color.

The nucleus is __________ & contains no nucleolus. This cell is called a ____________.

Back 52

Gliosis

Eccentric

Gemistocyte

Front 53

The __________ Astrocyte reacts acutely to injury and the __________ Astrocyte reacts in a chronic mode.

Back 53

Protoplasmic

Fibrillary

Front 54

The Astrocytes in the Purkinje layer of the Cerebellar Vermis are called ______________.

Back 54

Bergmann's glia

*w/ injury and Purkinje cell lost Bergmann's gliosis occurs

Front 55

What type of Astrocytes are seen in response to injury associated with Liver disease?

Back 55

Alzheimer type II

*nucleus swells 2-3 times its normal size, loses its chromatin, and becomes watery clear
*this change is initiated by high ammonia levels caused by the underlying Liver disease.

May also be caused by Wilson's Disease

Front 56

Thick, red linear structures resembling plump, red sausages. At an ultrastructural level, they are intracellular, representing swollen Astrocyte processes filled with glial filaments.

Back 56

Rosenthal fibers

Front 57

What diseases do you see Rosenthal fibers?

Back 57

Pilocytic astrocytomas
Craniopharyngiomas
Alexander's Disease

Front 58

____________ are round, gray-blue structures with concentric rings, which increase in proportion to age. They are particularly prominent beneath the pial & subependymal surfaces & around blood vessels.

Back 58

Corpora amylacea (amyloid bodies)

Front 59

Amyloid bodies are (inter/intra)cellular reflecting the deposition of a material called ____________ within the Astrocyte.

Back 59

Intra

Polyglycosan

Front 60

What is a systemic storage disease where you see deposition of polyglycosan?

Back 60

LaFora's Disease

*LaFora bodies are present in a variety of organs, including the CNS

Front 61

What two cells are considered the "third element" of the nervous system?

Back 61

Oligodendroglial cells & Microglia

Front 62

The Oligodendroglia are of ____________ origin.

Back 62

Neuroectodermal

Front 63

What is the function of the Oligodendroglial cell?

Back 63

Formation of myelin sheath by wrapping its cytoplasm around the axon in multiple, concentric lamellae, analogous to Schwann cell of the PNS.

It does NOT glue the nervous system together within a neuropil matrix, as does the Astrocyte

Front 64

What are the morphological characteristics of the oligodendroglial cell w/ H&E stain?

Back 64

small, round, dark "cookie cutter" nucleus, resembling a Lymphocyte

nucleus may be surrounded by a round, optically empty space or halo, giving the cell a "fried egg" appearance

Front 65

Three to five oligodendroglial cells in the gray matter may surround the body of the neuron. This is called:

Back 65

Benign satelitosis

Front 66

________________ are seen in association with the disease complex called multiple system atrophy.

Back 66

Glial cytoplasmic inclusions

Front 67

What do Glial cytoplasmic inclusions contain?

Back 67

protein alpha-synuclein

Front 68

What comprises multiple system atrophy?

Back 68

Sporadic olivopontocerebellar atrophy

Striatonigral degeneration

Shy-Drager Syndrome

Front 69

The microglial cells is of _____________ origin.

Back 69

Mesodermal

Front 70

The microglia represent a fixed CNS precursor of the ____________ system, which is activated by injury.

Back 70

Macrophage

*also have circulating pool of macrophages which enter the damaged CNS from the circulating blood

Front 71

What are the characteristics of a microglial cell?

Back 71

small, spindled or cigar-shaped nucleus

Front 72

The macrophage system, when activated by injury, removes damaged CNS tissue, with ultimate formation of a _________ or ________ as an end-stage lytic lesions.

Back 72

Cavity / Hole

*the nervous system heals by cavitation

Front 73

When activated in response to injury, spindled microglial nuclei become prominent and are referred to as:

Back 73

Rod cells

Front 74

There is also evidence that the microglia function as a __________ cell of the immune system.

Back 74

Dendritic

Front 75

______________ cells line the ventricular surfaces as a single layer of cuboidal or columnar cells.

Back 75

Ependymal

*represent modified Astrocytes based on the presence of GFAP-positive cytoplasmic processes

Front 76

Ependymal cells contain cilia during the fetal period which disappear after birth leaving only the basal body or ______________ of the cilia as an ultrastructural remnant.

Back 76

Blepharoplast

Front 77

Infections of the ventricular surface may denude scattered foci of Ependymal cells, which are replaced by reactive ____________ resulting in the formation of minute granular structures visible to the unaided eye as _____________ _____________.

Back 77

Astrocytes

Granular Ependymitis

*damaged Ependymal cells do not regenerate

Front 78

In certain instances of hydrocephalus, the tight ependymal cell junctions may be opened, w/ resultant insudation of CSF into the adjacent parenchyma. This is called:

Back 78

Hydrocephalic edema