Introduction to Neuropathology Flashcards
What is the main question you should ask regarding neurolocalization?
Is the problem general or focal
What type of cells are ependymal cells?
Glia
What cell serves the purpose of the fibroblast in the CNS?
Astrocytes
There are no astrocytes in the _____________.
choroid plexus
_________ are the largest and most metabolically active cells in the body.
Neurons
________ are usually the largest neurons.
Motor neurons
The size of the soma parallels the length of the ____________.
axons
Like cancer cells, neurons have very prominent ___________.
nucleoli
Hematoxylin stains ___________, while eosin stains ___________.
DNA and RNA; protein
What is the general histologic appearance of the cortex?
The cortex has a lot of neuronal cell bodies (far denser than white matter), and you can often notice the different layers.
Describe four main ways neurons react to injury.
- Ischemic neurons undergo necrosis
- Neurons with damaged axons undergo chromatolysis
- Viral particles can be taken up by neurons
- Storage and neurodegenerative disorders can lead to accumulated protein within cells
What are Lewy bodies?
Accumulation of protein in the cytoplasmic area near the nucleus (often seen in the neurons of the substantia nigra)
The neurofibrillary tangles of Alzheimer’s are better seen on ______ staining than H&E staining.
silver
What enzyme catalyzes the reaction that produces amyloid plaques?
Beta-secretase (alpha secretase does not lead to plaques)
Transecting an axon leads to ____________, a process called Wallerian degeneration.
necrosis of the axon distal to the cleavage
Swelling of the neuronal cell body indicates ____________.
that an axon has been destroyed
Why can the brain not fill in necrotic, emptied-out areas?
Because there is no collagen for cells to migrate on
Oligodendrocytes have a ___________ look on histologic exam due to low levels of cytoplasm.
“fried egg”
Although ependymal cells are similar to epithelium, there is one important cellular distinction. What is it?
Ependymal cells do not secrete a basement membrane! Instead, they have astral processes that extend into the brain.
What immunostain (i.e., receptor antibody) binds to microglia?
CD68
How can you differentiate myopathy from denervation?
Myopathy: elevated CK, proximal weakness, EMG changes
Denervation: normal CK, distal weakness, different EMG changes
Judging by what you know about the relationship between soma size and axon length, will the soma of pyramidal cells be bigger or smaller than those of upper motor neurons?
Pyramidal somas will be smaller –their axons are much shorter than motor neuron axons
True or false: neurons that undergo chromatolysis are going to die.
False! They often die, but many peripheral cells will bounce back and live again.
Eosinophilia means ____________ cytoplasm.
pink
Basophilia means ____________ cytoplasm.
purple/blue
What kind of glia are a type of ciliated epithelium?
Ependymal cells
How fast can regrowing axons grow (as in, how much length per day)?
Between 0.5 mm/day and 5 mm/day
“Onion-bulb” demyelination is a type of ____________ demyelination.
segmental
What kind of glia are radial glia?
Astrocytes
What is GFAP and what cell does it stain?
Glial fibrillary acidic protein; it is found on astrocytes
Differentiate perimysium and endomysium.
Perimysium: covering sheath around muscle
Endomysium: little sheaths that go between individual muscle fibers that carry capillaries
What is DAC?
Dystrophin-associated complex –a group of proteins that assists dystrophin
What is the role of phosphocreatine?
It serves as a source of phosphorus for creatine kinase (CK) to add to ADP; this allows for an extra source of ATP when supplies are low.
Can a motor unit contain more than one type of muscle fiber?
No, motor units will either be all fast- or all slow-twitch fibers –not a mixture
Describe the roles of endoneurium, perineurium, and epineurium.
Endoneurium is the small amount of matrix between axons in a bundle; perineurium is the material that connects different axons together within the bundle; and epineurium is the sheath around the axon bundle.
Each segment of myelin represents how many Schwann cells?
One
True or false: unmyelinated axons in the periphery are not in contact with Schwann cells.
False, every PNS axon is covered by a Schwann cell, but the Schwann cell is not spiraled around multiple times
Defective regeneration of a PNS axon can lead to a ____________.
neuroma
Distal neuropathy is thought to be caused by what basic problem?
inability of the body to meet the metabolic demands of the neuron (which is why it starts distally)
Give an example of two disorders (or groups of disorders) that have an “onion-bulb” demyelination pattern.
- Degenerative demyelinating neuropathies
- Charcot-Marie-Tooth neuropathy
Actin connects to the _________ lines.
Z
