Flashcards in 6. Neuropathology Deck (82)
what is the neuronal capacity to regenerate?
limited for neural components, no regen ability for neurons themselves
what is the infrastructure of the nervous system as opposed to that of the rest of the body?
NS = glial rather than fibroblastic.
does the NS have typical lymphoid drainage?
define Primary Neurological Disease
disorders which begin in or are restricted to the NS. ex: Alzheimers, MS, astrocytomas, AMS, Huntingtons, Parkinson's
define Secondary Neurological Disease
conditions that affect the NS as a consequence of non-CNS disease. Ex: metastatic carcinoma, syphilis, HTN, emboli, trauma
define System Disorders
maladies of the whole body which in the NS play a critical role. ex: enzyme def, atherosclerosis, poisonings, hypoxia
what will happen to severely damaged neurons?
eventually they will disappear
a contracted neuron with hypereosinophilia of the cytoplasm and pyknosis of the nucleus has undergone what?
gradual shrinkage of the cell body and withering of the dentritic tree indicates that what has happened?
how much neuronal loss has to occur to be seen microscopically?
if in a Nissl preparation, the Nissl granules have disappeared, what is the problem?
retrograde degeneration following injury or transection of axons will appear as what?
Mineral deposits in damaged neurons is a sign of what?
phagocytosis of a degenerated neuron by macrophages is called what?
what is lipofuscin?
a wear and tear pigment, mixture of lipids and proteins that accumulates during the course of aging
what cells exhibit lipofuscin earlier than others? what are relatively resistant?
inferior olivary nuclei show earlier, purkinje are resistant.
if lipofuscin like material is seen in neurons in early life, what is it a sign of?
what can cause neurons to distend, enlarge, or assume a globular shape?
accumulation of sphingolipids or gangliosides. due to catabolic enzymatic block
what are neurofibrillary tangles?
bundles of abnl filaments seen in disorders such as Alzheimer's
what are inclusions? in what diseases might we see them?
may be nuclear and/or cytoplasmic. seen in Parkinson's (Lewy bodies) or herpes (Cowdry type A inclusions)
what is wallerian degeneration?
degeneration of an axon distal to an injury.
what is dying-back'?
degeneration of the most distal segments of an axon due to inability of the cell body to maintain adequate plasmic flow, or produce needed nutrients.
when is dying back seen?
in some toxic neuropathies, and certain neurodegen diseases
what are axonal spheroids?
focal bulbous swelling of axons. usually the result of injury
what is demyelination: primary vs secondary?
primary: insult to myelin sheath or myelin forming cell
secondary: due to degen of axons as in wallerian, or dying-back.
what is the myelin-forming cell in CNS?
what is the myelin-forming cell in PNS?
when is loss of dendritic branches seen?
dev disorders (both congen and acquired)
what composes neuroglia?
astrocytes, oligodentrocytes, ependymal cells, epithelium of choroid plexus.
what are the functions of neuroglia?
diverse, including to maintain constant internal envt, assist with neuronal function, protect CNS/PNS.
what do astrocytes do?
respond to almost any stiumlus, first by enlarging and then by retracting.
what type of cell mends an injured area?
cell processes of fibrous astrocytes form a network - glial scar or gliosis
what are Alzheimer's Type II glia?
astrocytes proliferate, undergo an alteration in conditions in which blood and CSF ammonia levels are elevated. ex: hepatic encephalopathy, or with elevated serum electrolytes
what do oligodendrocytes do?
form and maintain central myelin,
what will the destruction of oligodentrocytes lead to?
demyelination as in progressive multifocal leukoencephalopathy (PML) which is a viral condition.
ependymal and choroid plexus cells: what is their origin?
what do ependymal cells do?
line ventricles, maintain equilibrium between cerebrospinal and interstitial fluids of the brain.
what do ependymal cells look like?
tall columnar ciliated cells, show variation in cell config depending on location/function.
what is the response of ependymal cells and choroid plexus to an insult?
to die. they are not helpful.
when do ependymal cells or choroid plexus cells become of interest?
if they disappear or become neoplastic
what do microglial cells do?
not glial cells. specialized monocyte/macrophage which arises in the bone marrow, and populates the CNS pre birth. assist in remodeling of fetal CNS by phagocytizing cells that die.
what do microglial cells look like?
small, dense, elongated nuclei, no identifiable cytoplasm except with special stain.
how do microglia arrange themselves?
thin branches of cytoplasm radiating from nuclear zone, establish non-overlapping territories
what are the functions that microglia can carry out?
-can become macrophages
-can be immunocompetent cells, presenting antigen and secreting cytokines
-can proliferate and assume phenytope of macrophages when there is neuronal death due to tumor.
-if there is neuronal death by virus, microglial stars/nodules form
schwann cells do what?
similar functions to astrocytes, oligodendrocytes, and microglia in the PNS.
what can schwann cells do to motor and sensory axons?
ensheathe to increase conduction velocities
describe Selective Vulnerability. example?
some regions of the brain are more affected than others by insult or injury. ex: cells of hippocampus show ischemic/anoxic changes much earlier than other regions of the brain.
what is released in presynaptic terminals during anoxia?
how does glutamate in the presynaptic terminals cause toxicity?
impaired cellular uptake, concentration of glutamate rises to toxic levels by binding to NMDA receptors, opening up Na and Ca channels, causing osmotic swelling due to Na entry, neuronal death due to entry of Ca.
deficiency of Vit B1 causes what?
B1 = thiamine. causes Wernicke's encephalopathy. destruction seen in mammillary bodies, wall of third vent and floor of 4th vent.
deficiency of Vit B12 causes what?
destruction of the white matter in the dorsal and lateral columns of spinal cord
Vasogenic edema is what?
BBB is compromised, allowing some fluid to escape from intravascular space to intercellular space/brain parenchyma
cytotoxic edema is what?
glia or neurons enlarge due to changes in cell membranes. seen with hypoxia/ischemia
how is raised Intracranial Pressure defined?
as more than 200 mmH2O with patient recumbent
what are herniations?
movement of soft neural tissues across or against other firmer tissue (falx, tentorium)
what causes herniations?
mass effect, raised ICP.
what is hydrocephalus?
excess accumulation of CSF in the ventricular system.
what causes most hydrocephalus?
decr flow through ventricular system, impaired resorption of CSF. rarely, incr production of CSF (choroid plexus tumors)
in the CNS, an infarction turns into what kind of tissue?
pus/liquid rather than scarring as in the rest of the body
where is the Nissl substance located? what is it?
RER for neurons. located in the cytoplasm. most neurons make huge amounts of proteins.
cajal silver stain picks up what?
neuron cell body and dendritic processes.
Luxol fast blue stains what?
astrocytes have what in their intermediate filament that is unique to astrocytes?
what are some general indicators that a pathological process may be present?
Alterations within, shape changes of, or variation in number of, the basic cell types in the CNS
what is a process in the neurons that indicate pathology?
if they are RED. Red because 02 has been shut off, the 3 Carbon acids build up (ex: lactic acid), cell cytoplasm becomes acidic.
what is a process in dendrites that indicates pathology?
dendritic pruning. You wouldn’t pick this up with H and E
what is a process in neuronal bodies that indicates pathology?
Central chromatolysis: Nissl has pushed out to periphery, lysed. Something bad has happened to axon and cell body is swelling.
what does a lysosomal storage disease process look like?
Large amount of abnormal material in cytoplasm displacing nissl material and nucleus. pink fluffy stuff that the cell can't digest.
what are Lewy bodies/what process do they indicate?
gross: lightened substantia nigra due to gliosis where SN should be. indicates Parkinson's. micro: round bodies found in SN.
what is proof that someone had rabies?
red inclusions in Purkinje cell nuclei of cerebellum, or pyramidal cells of hippocampus.
what are Bunina bodies? where found?
Red, proteinacious aggregates in cytoplasm. Highly suggestive but not proof of ALS. Found in anterior horn.
what is segmental degeneration? what does it look like?
myelin broken down, axon not damaged. may be immumo process. slows transmission down axon. cell body not swollen.
what general role do astrocytes play?
supportive functions: growth hormones, maintain homeostasis. foot processes around capillaries create BBB
Alzheimer's type 2 astrocytes: see in Alz disease? what do they indicate?
not seenin Alz: seen in cases of severe hepatic dysfunction. Nucleus swells to twice size, chromatin is pushed to side. Center becomes clear.
what are microglia?
not glia. kind of territorial sensory system, have receptors on their processes
microglia have the ability to turn into what?
macrophages. can perform neuronophagia, seen in diseases of CNS. thse were the ones in the movie about damage to CNS by a laser.
what type of cell provides the BBB? which part of that cell?
foot processes of the astrocytes.
vasogenic edema predominantly affects white or grey matter?
white matter. injury to cerebral blood vessels.
vascular permeability/extravasation of proteins in vasogenic v cytotoxic edema?
vasogenic: edema fluid is plasma filtrate including serum proteins. cytotoxic: plasma ultrafiltrate, not proteins.
what is the appearance of astrocytes when they have become swollen/reactive/
ground glass appearance of background
what is Reye's syndrome?
cause of acute brain edema: acute illness in kids who are given aspirin following resp/viral infection or chickenpox. coma --> death.