Neuropathology 1, basic principles & Cerebrovascular disease Flashcards
what makes up the peripheral NS?
the 31 pairs of spinal nerves and 12 cranial nerves
Give the layers of the CNS?
Dura
tough, fibrous, bridges crevices, attached to skull
Arachnoid
delicate sealed bag for CSF, bridges crevices
Arachnoid trabeculae
ropes across subarachnoid space
pia mater
delicate and dips into crevices
what are the cellular components of the CNS?
Neurones Glial cells Blood vessels Microglia Connective tissue (meninges)
What are glial cells?
-examples? (3)
supporting system for neurones and their dendritic and axonal processes
astrocytes
(regulate transmission of electrical impulses)
oligodendrocytes
(wrap around axons forming myelin sheath)
ependyma
(line the ventricular system)
what are the 4 ways in which neurones respond to injury?
acute neuronal injury
simple neuronal atrophy (in hypoxia)
Sub-cellular alterations
Axonal reaction
Hypoxic damage to CNS
-what occurs in neurones?
-activation of glutamate receptors and uncontrolled Ca entry into cell
they can’t use anaerobic glycolysis
neuronal degeneration
- what is an axonal reaction?
- what is the response to axonal injury? (7)
-a reaction within the cell body that is associated with axonal injury
-inc RNA and protein synthesis swelling of cell body peripheral displacement of nucleus enlargement of nucleolus central chromatolysis anterograde degeneration of axon occurs distal to sire of injury breakdown of myelin sheath
Gliosis
- what is it?
- indicates what?
- what happens to astrocytes?
- nuclear and cytoplasmic changes?
- appearance of old lesions?
- a nonspecific reactive change of glial cells in response to damage to the central nervous system
- CNS injury
- undergo hyperplasia and hypertrophy
-N: enlarges, becomes vesicular and nucleolus prominent
C: expansion with extension of ramifying processes
-nuclei become small and dark and lie in a dense net of processes
Oligodendrocytes
- function?
- reaction to injury
- injured in what?
- wrap around axons of neurones to from myelin sheath
- limiters reaction
- demyelinating disorders
Ependymal cells
- function?
- rection to injury?
- what occurs when these cells are disrupted?
- what produces changes in these cells?
- line the ventricular system
- limited
- local proliferation of sub-ependymal astrocytes to produce small irregularities on the ventricular surfaces termed ependymal granulations
- infectious agents e.g. viruses
Microglia
- function?
- response to injury? (4)
-fixed macrophage system
-proliferating
developing elongated nuclei (rod cells)
forming aggregates around small foci of tissue necrosis (microglial nodules)
Congregate around portions of dying neurones (neuronophagia)
Vascular supply to the NS
- brain receives what % of CO and O2?
- needs what from of energy?
- what maintains cerebral blood flow?
- what vessels supply blood to brain?
- 15% of CO and 20%of O2 consumed by body
- brain requires active aerobic metabolism of glucose
-autoregulatory mechanisms
(vasculature constricts on response to abnormally high pressure and dilates in response to hypotension)
-internal carotid and vertebral arteries = circle of willis
-
consequences of an anterior cerebral artery blockage? (3)
-frontal lobe dysfunction
contralateral sensory loss in foot & leg
paresis of arm & foot, relative sparing of thigh & face
consequences of an middle cerebral artery blockage?
-depends on whether its dominant of non dominant cortex contralateral hemiparesis contralateral hemisensory loss Aphasia/dysphasia apraxia
what areas does the vertebrobasilar artery supply? (3)
brain stem
Cerebellum
Occipital lobe
