PATHOLOGY- cerebrovascular disease Flashcards
layers of the scalp?
SCALP
Skin subcutaneous
Connective tissue
Aponeurotic
Loose areolar connective tissue
Pericranium (periosteum)
what are the meninges?
Pia mater
Arachnoid Mater
Dura Mater
what are the cellular components of the CNS?
-Nerve cells (neurons)
-Glial cells
-Microglia
-Supporting structures (connective tissue, meninges, blood vessels)
What are examples of Glial cells?
-astrocytes
-Oligodendrocytes
-Ependymal cells
what can damage to nerve cells and/or their processes lead to in the brain?
Rapid necrosis with sudden acute functional failure (as seen in “stroke”)
Slow atrophy with gradually increasing dysfunction (as seen in age-related cerebral atrophy)
what is red neurone?
- a pathological hallmark of lethal injury to the neurone
-typically occurs in hypoxia/ischaemia
-it is usually visible 12 to 24 hours after an irreversible ‘insult’ to the cell and results in neuronal cell death
basically a dying neurone
what is a red neurone pattern?
-shrinking and angulation of nuclei
-loss of necleolus
-intensely red cytoplasm
how do neurons respond to axonal injury?
Increased protein synthesis -> cell body swelling, enlarged nucleolus
Chromatolysis – margination and loss of Nissl granules
Degeneration of axon and myelin sheath distal to injury
how do axons respond to chronic degeneration?
simple neuronal atrophy
-shrunken, angulated and lost neurons, small dark nuclei, lipofuscin pigment, reactive gliosis
when are inclusions seen in the brain?
sub cellular alterations (inclusions)=
-common in neurodegenerative conditions e.g. neurofibrillary tangles in Alzheimer’s disease
-viral infections affecting the brain
-appear to accumulate with age
what wraps around the axons of the CNS forming myelin sheath?
Oligodendrocytes
what reaction fo Oligodendrocytes have to injury?
-variable patterns of demyhelination
-variable degrees of demyelination
-apoptosis
what occurs to oligodendrocytes in demyelinating disorders?
oligodendrocytes are damaged
what can damage to the myelin sheath result in?
-reduced conduction
-axons are exposed and so are more likely to be injured
where are astrocytes foubd?
-in the CNS
-astrocyte processes envelope synaptic plates and wrap around vessels and capillaries within the brain
role of astrocytes?
-Ionic, metabolic and nutritional homeostasis
-Work in conjunction with endothelial cells to maintain the blood brain barrier
-The main cell involved in repair and scar formation given the lack of fibroblasts
what is the most important histopathological indicator of CNS injury?
Gliosis (an astrocyte response)
describe what happens in gliosis
Gliosis occurs due to injury to the CNS
-Astrocyte hyperplasia and hypertrophy
* Nucleus enlarges, becomes vesicular and the nucleolus is prominent
* Cytoplasmic expansion with extension of ramifying processes
Old lesions – translucent, nuclei become small and dark and lie in a dense net of processes (glial fibrils)
where are Ependymal cells located?
-line the ventricular system
what is the reaction that ependymal cells that to injury?
-limited reaction to injury
-important for infection (infection can pass from one set of ependymal cells to another through CSF)
-disruption of these cells often associated with a local proliferation of sub ependymal astrocytes to produce small irregularities on the ventricular surfaces termed ependymal granulations
what is the clinical relevence of ependymal cells?
-infectious agents including viruses produce changes in ependymal cells
-often site of tumour formation which can obstruct the flow of CSF
where are microglia derived from?
-embryologically derived
what is the role of microglia cells?
-function as a macrophage system, phagocytosis
what reaction do microglia have to injury?
-microglia proliferate
-recruited through inflammatory mediators
-form aggregates (around areas of necrotic and damaged tissues)
