Nervous System Flashcards
Grey matter
neurons – horns of the spinal cord, cerebellar/cerebral cortex
White matter
myelinated axons – medullary center of brain, outer cortex of spinal cord
What is the function of oligodendrocytes?
Form myelin the wraps around axons (CNS)~ similar to Schwann cells in PNS
What is the function of Astrocytes?
cell processes form BBB and repair CNS after injury
What is the function of Microglia?
Phagocytic cells “fixed macrophages of CNS”
What is central chromatolysis?
Response of nervous system to injury involving degenerative change & swelling with dispersal of Nissl substances
What is neuronophagia?
Occurs when microglia surround degenerate or necrotic neurons and phagocytose it to remove debris
What are the histologic characteristics of axonal (Wallerian) degeneration?
i. Axon degeneration (spheroid appearance~ swollen/eosinophilic)
ii. Gitter cells remove axon & myelin debris (microglia with foamy cytoplasm)
iii. Empty dilated axon sheaths cant regenerate in CNS
What is a spheroid?
Focal axonal swellings filled with degenerate organelles
What is astrocytosis?
increase size & number of astrocytes in response to injury
What are gemistocytic astrocytes?
Plump reactive astrocytes with eosinophilic cytoplasm~ look like necrotic neurons but have healthy nucleus
What is the appearance of Alzheimer’s type II astrocytes, and what disease process are these cells typically seen in?
appear “reactive” found around neurons, enlarged with vesicular nuclei. Found with hepatic encephalopathy
What are the different types of hydrocephalus?
In which breeds of dog is hydrocephalus most common?
Internal (fluid in ventricles- most common), External (fluid in arachnoid space) & communicating (fluid in ventricles & arachnoid space)
- Brachycephalic dogs
Hydranencephaly
near complete/ complete absence of cerebral hemispheres~ have CSF fluid filled sacs formed by meninges. Often associated with arbovirus or pestivirus
Porencephaly
cystic cavitation of brain (involves white mater)~ occur later in development
Lissencephaly
brain lacking normal gyri & sulci, this is not normal for domestic mammals (everything that is non-mammal normally lissencephalic)