Week 3 - F - Neuropathology 1 - Glial cells, CNS injury, stroke Flashcards
What are the types of CNS glial cell?
Astrocyte Microglia Oligodendrocytes Ependymal
What is the function of the glial cells?
Astrocyte - important in maintaining the BBB and involved in electrolyte balance Microglia - main immune surveillance cell of the brain - phagocytic and engulf bacteria Oligodendrocytes - produce myelin in the CNS to wrap around axons Ependymal cells - lines the choroid plexus of the ventricles in the brain
Nervous system injury can arise from a variety of places Hypoxia is an important causative factor of nerve cell injury and can be caused by different conditions Damage to nerve cells and/or their processes can lead to: Rapid necrosis with sudden acute functional failure - when is this seen? Slow atrophy with gradually increasing dysfunction - when is this seen?
Rapid necrosis with sudden acute functional failure is seen in events such as a stroke where there is no blood supply leading to cell death Slow atrophy with gradually increasing dysfunction is seen in normal age related cerebral atrophy
The neuron is the main communicating cell of the CNS consisting of the axon, covered by myelin sheath What are the gaps in the myelin sheath that help speed up the rate of conduction? What is this type of conduction known as?
The gaps are known as the nodes of ranvier - the help speed up the rates of conduction Known as saltatory conduction
Acute neuronal injury occurs in the context of hypoxia or ischaemia (ie cerebral infarct) How is the neuron described here? it is essentially a term for what a dying neuron looks like
The neuron is described as a red neuron here - it become shrunken
On histology , why is this neuron the colour red? in acute neuronal injury
It is red as the proteins that are left stain red - eosinophilic
Other neuronal responses to neuron injury can occur that dont involve the acute neuronal injury response to hypoxia One of these is Wallerian degenration, what does this term mean?
This is where degeneration of the axon and myelin sheath occur distal to the site of injury
What is the star shaped glial cell with multipolar cytoplasmic processees? What is its function?
This is the astrocyte Important in maintaining homesostasis and the blood brain barrier (BBB)
What neurotransmitter precursor do astrocyte supply?
They supply glutamine - precursor to neurotransmitter glutamate
What is the most important histopathological indicator of CNS injury, regardless of cause?
This is gliosis - Gliosis is a nonspecific reactive change of glial cells in response to damage to the central nervous system (CNS).
What happens in gliosis?
In glisois there is astrocyte hyperplasia and hypertrophy PIc on left shows progression of CNS injury from red neurones forming (hypoxia/infarct related) to eventual gliosis
WHat type of glial cell features in which demylinating disorder?
Oligodendrocytes feature in the demyelinating disorder multiple sclerosis and are sensitive to oxidative damage
Membrane depolarisation jumps from one node to the next through “saltatory conduction” at a much more rapid rate than would occur through depolarisation alone. Myelin insulation also helps to contain depolarisation locally (preventing leakage to adjacent axons) and provides a barrier to injury. If there is axonal damage, what is the type of degeneration known as again?
This anterograde degeneration (wallerian’s degeneration) where axonal and myelin tissue dies distal to the site of injury
The cerebral circulation stems with the circle of willis Which arteries are involved in the ciicle of willis?
Anterior cerebral arteries, anterior communicating artery, middle cerebral artery/internal carotid artery, posterior communicating artery, posterior cerebral arteries
At the circle of willis, which arteries come from the internal carotid artery? Which artery comes off the basilar artery immediately proximal to the posterior cerebral arteries?
Internal carotid artery - gives ophthalmic artery, anterior choroidal, and middle cerebral - opthalmic artery travels beside the sphenoid sinus Proximal to the posterior cerebral is the superior cerebellar artery
WHich arteries come off the basilar artery from posterior cerebral to the vertebral arteries? What are the two inital arteries coming off the vertebral artery?
Basilar - posterior cerebral, superior cerebellar artery, pontine arteries, anterior inferior cerebellar artery Vertebral arteries - posterior inferior cerebellar artery, branch from each vertebral to forma anterior spinal artery
Which artery supplies blood to most midline portions of the frontal lobes and superior medial parietal lobes? Which artery supplies blood to the majoirty of the temporal lobes? What does the posterior cerebral artery mainly supply?
Midline portions of frontal lobes and superior medial parietal lobes - anterior cerebral artery (blue) Majority of temporal lobes - middle cerebral artery (purple) Posterior cerebral artery mainly supplies the occipital lobe (green) - and the inferior temporal gyrus
Which artery supplies the major bulk of the sensory and motor cortex? Which artery supplies sensory and motor innervation to the trunk and legs? (think of the artery borders and the homunculus)
Middle cerebral artery supplies major bulk of the sensory and motor cortex The anterior cerebral artery supplies the legs and trunk with sensory and motor innnervation - remember anterior cerebral supplies midline portions of frontal lobes and superior midline of parietal
State which artery supplies each box? What is the anterior choroidal artery a branch of?
Blue box - anterior cerebral artery (legs and trunk) Brown box - middle cerebral artery Pink box - posterior cerebral artery Red box - posterior cerebral artery (deep branches) Anterior choroidal artery is a branch of the internal carotid artery
