What do abnormal lysosomes in the neurons do?
gradually fill the cell body and processes, leading to destruction of the neuron
Bielschowsky stain shows normal axons and dendrites but also reveals the lesions of ______.
What do cross bridges of tau protein and microtubule associated proteins (MAPs) do?
they link neurotubules together
What is the main job of the oligodendrocyte?
make myelin in the CNS
Where is the most common site of Wallerian degeneration?
the corticospinal tract
What are ependymal cells?
cells that line the ventricular cavities
What is neuropil?
the matrix of the cerebral gray matter
_____ are the target for the viral infection in AIDS.
Repair by _____ is less effective than collagenous repair and cysts are often the consequence of large destructive lesions in the CNS.
Intracytoplasmic neuronal inclusions can be seen in______ and _____.
cytomegalic inclusion body disease; rabies
This is diffuse deposition of Rosenthal fibers resulting in white matter degeneration and neuro dysfunction.
These are extracellular and distal manifestations of Alzheimer's disease where amyloid accumulates in the brain.
classic neuritic plaques
What is the pathognomonic feature of Pick body disease (dementia)?
____ stain shows normal axons and dendrites but also reveals the lesions of Alzheimer's disease.
In the adult brain, the neuron is a _____, _____ cell.
What is the H&E stain for?
DNA/RNA but not neuronal processes
These are homogenous, eosinophilic, elongated, or globular inclusions in astrocytic processes seen in old brain scars.
What is the perivascular (Virchow-Robin) space?
subarachnoid space that dips into the CNS
How are neurotubules linked together?
cross bridges of tau protein and microtubule associated proteins (MAPs)
What are classic neuritic plaques?
extracellular and distal manifestations of Alzheimer's disease where amyloid accumulates in the brain
What is the pathognomonic feature of Parkinson's disease?
____ are the most sensitive cell in the brain to sudden decreases in O2 or glucose.
How long can neurons survive anoxia?
5-15 minutes max
Can oliodendrocytes regenerate?
regeneration is very limited
The neuropil is traversed by ______.
Axons and dendrites are best viewed using ____ stains.
Name 5 cells within the brain.
- ependymal cells
In _____, abnormal filaments appear in the perikaryon, forming neurofibrillary tangles (NFTs).
What is the subarachnoid space that dips into the CNS called?
the perivascular (Virchow-Robin) space
What can persistent microglia activation cause?
damage --> Alzheimer's, Parkinson's, HIV encephalopathy, etc
How can ischemic neurons be ID'd histologically, and what are they called?
they're shrunken, eosinophilic, and nucleus is pyknotic; called red cell neurons
What is the major scar former in the CNS?
Myelin is a special cell membrane-derived insulation for axons which facilitates efficient ______ conduction.
What is the largest, longest, and most metabolically active cell in the body?
How are oligodendrocytes different than Schwann cells?
they're in the CNS and they myelinate many cells at once with a different type of myelin
Neurons are in close contact with their "caregivers," the _____.
Where do microglia come from?
Astrocyte cytoplasm contains intermediate filaments that are made of a distinct protein, _____.
glial fibrillary acidic protein (GFAP)
What are tanycytes?
ependymal cells that serve various neuroendocrine or ionic transport functions
What is Wallerian degeneration?
an axonal alteration where the axon is transected and the portion distal to the transection degenerates bc the energy source is cut off
What are the functions of microglia?
- monitor CNS environment
- restore homeostasis
What is Alexander disease?
diffuse deposition of Rosenthal fibers resulting in white matter degeneration and neuro dysfunction
In Alzheimer's disease, abnormal filaments appear in the _____, forming _____.
perikaryon; neurofibrillary tangles (NFTs)
Why are glial fibrillary acidic proteins (GFAPs) important?
Abs to them can demonstrate reactive and neoplastic astrocytes; mutations of them cause Alexander disease
What are microglia?
phagocytes/APCs in the brain (but have to migrate there)
Describe unique features of the organelles w/I a neuron.
- large, round vesicular nucleus
- prominent nucleolus
- stacks of rER (Nissl substance)
What is the difference between a neurofilament and a neurotubule?
- neurofilament = 10nm
- neurotubule = 20-26nm polymers of alpha and beta tubulin
What is the pathognomonic feature of Alzheimer's disease?
During brain development, certain astrocytes known as ______ have a key role as "scaffolds" to allow neuronal migration.
The matrix of the cerebral gray matter is the _____.
What are Rosenthal fibers?
homogenous, eosinophilic, elongated, or globular inclusions in astrocytic processes seen in old brain scars
What is cytoplasmic lipofuscin?
a lysosomal enzyme/neuronal storage disease
Why do Alzheimer type II astrocytes develop?
due to severe liver damage in hepatic encephalopathy
What are some pathologies of oligodendroglia?
- they are lost in MS
- infected by viruses in subacute sclerosing panencephalitis and progressive multifocal leukoencephalopathy
- accumulate material in lysosomes in metachromatic leukodystrophy
This occurs when the neuronal cytoplasm becomes smooth and the nucleus is displaced toward the periphery; it means that the neuron has been disconnected from its target.
What is central chromatolysis and what does is signify?
- when the neuronal cytoplasm becomes smooth and the nucleus is displaced toward the periphery
- means that the neuron has been disconnected from its target
What are some ependymal cell pathologies?
disruption and loss in hydrocephalus, bacterial ventriculitis, or viral infections
Do astrocytes form the BBB?
no, but they help regulate/modulate it