Flashcards in Pathology Deck (71)
What are the cellular components of the CNS?
Glial cells: astrocytes, oligodendrocytes, ependymal cells
Supporting structures: connective tissue, meninges, blood vessels
What are the 2 ways that neurones will respond to injury?
Rapid necrosis with sudden acute functional failure
Slow atrophy with gradually increasing dysfunction - seen in age related cerebral atrophy
When will you see a red neurone?
Context of hypoxia/ ischaemia
Visible 12-24 hours after an irreversible insult to the cell
Results in neuronal cell death
What is the pattern to acute neuronal injury?
Shrinking and angulation of nuclei
Loss of nucleolus
Intensely red cytoplasm
How will axons respond to injury?
Increased protein synthesis; cell body swelling and enlarged nucleolus
Chromatolysis; margination and loss of nissl granules
Degeneration of axon and myelin sheath distal to the injury - wallerian degeneration
What is simple neuronal atrophy?
Shrunken, angulated and lost neurones
Small dark nuclei
What is gliosis?
Gliosis is a nonspecific reactive change of glial cells in response to damage to the central nervous system
Hypertrophy and hyperplasia of astrocytes
What are sub-cellular alterations (inclusions)?
Common in neurodegenerative conditions such as neurofibrillary tangles in alzheimer's
Inclusions appear to accumulate with ageing
Will get inclusions in viral infections
What is the function of an oligodendrocyte?
Wraps around axons to form a myelin sheath to facilitate salutatory conduction
What will occur with damage to an oligodendrocyte?
Variable pattern of demyelination
Are oligodendrocytes sensitive to oxidative damage?
What is an astrocyte?
Star shaped cell with multipolar cytoplasmic processes
Where can strocytes be found?
Present throughout the CNS
Astrocytic process; envelops synaptic plates
Wraps around vessesl and capillaries within the brain
What are the roles of astrocytes?
Ionic, metabolic and nutritional homeostasis
Work in conjunction with endothelial cells to maintain the BBB
Main cell involved in repair and scar formation - gliosis
Where can you find ependymal cells?
What occurs with disruption to these cells?
Local proliferation of sub-ependymal astrocytes to produce small irregularities on the ventricular surfaces termed ependymal granulations
What is the microglia response to injury?
Recruited through inflammatory mediators; forms aggregates around areas of necrotic and damaged tissues
What is the difference between M1 and M2 microglia?
M2; anti-inflammatory, phagocytic, more acute
M1; pro-inflammatory, more chronic
What are causes of nervous system injury?
Toxic insult - exogenous and metabolic disruption within brain releasing noxious substances
What can result in hypoxia?
What occurs in the brain cells after the onset of ischaemia?
Mitochondrial inhibition of ATP synthesis leading to ATP reserves being consumed within a few minutes - underlies rapid loss of consciousness in hypoxia
What occurs in terms of glutamate in excitotoxicity?
Glutamate released by depolarising neurone
Uptake of glutamate inhibited at astrocytes
Glutamate storm and excitation
Increased calcium resulting in protease activation, mitochondrial dysfunction and oxidative stress
What results in cytotoxic oedema?
What results in ionic oedema?
Excess water intake; SIADH
What results in vasogenic oedema?
Which areas of the brain does the anterior cerebral artery supply?
Midline portions of the frontal lobes and superior medial parietal lobes.
Which areas of the brain does the middle cerebral artery supply?
Portion of the frontal lobe and the lateral surface of the temporal and parietal lobes, including the primary motor and sensory areas of the face, throat, hand and arm, and in the dominant hemisphere, the areas for speech
Which areas of the brain does the posterior cerebral artery supply?
What is global hypoxic ischaemia?
Generalised reduction in blood flow/ oxygenation