Cells Of Nervous System Flashcards
What happens to grey matter in Weigert’s stain & why?
Remains unstained
Contains neurone cell bodies
No axons, no myelin, no cholesterol
Name a stain for lipids. What does it stain in the axon & why? What part of the brain stains darkly?
Weigert's stain. Myelin sheath (cholesterol) White matter (contains myelinated axons)
What % of the brain & spinal chord is white matter?
60%
What % of O2 delivered to the brain via the blood system is used by white matter?
Only 6%
It has low O2 demand
White matter is found as tracts. Define a tract.
Bundles of axons
Of similar function
Connecting one part of CNS to another
White matter are also found as fascicles. How is this different to a tract?
Bundle of axons (like tract)
BUT of >1 function
Going in opposite directs
Which fasciculus connects the ‘language area’ to the ‘speech area’
The arcuate fasciculus
Connects Wernicke’s to Broca’s area
Name the 2 structures in the cerebral hemisphere made completely of white matter
Internal capsule (tracts from the brainstem/thalamus to cortex, back from cortex) Corpus callosum (an enormous commisure)
Name the 2 basic organisations of grey matter
Nuclei
Laminae
What % of the brain is grey matter & how much of the delivered O2 does it use?
40% volume
Uses 96% O2
High metabolic demand
How many layers are there in the cerebral & cerebellar cortex?
3 in each
What is the most superficial layer of grey matter called?
Molecular layer
What do association fibres connect & where do they run?
Areas if the same hemisphere.
Run out if cortex, into medulla below, back up into cortex.
What is the predominant cell type in the CNS?
Neuroglial (glial) cells
10x more than neurones!
What is the function if oligodendrocytes?
Same as Schwann in PNS
Myelinate several (10-15) axons
Myelin sheath
Processes of what cell form the blood brain barrier by wrapping around capillaries?
Astrocytes
Astrocyte processes make contact with neuronal cell bodies to regulate extra cellular concentrations of….
K+
Ca2+
Glutamate
Name a substance produced by astrocytes
GFs
Cause neuronal development & axon production
Name another function of astrocytes
Help neuronal migration
(Eg developing layers if cerebral cortex)
Important in synapse formation
What cell type do some astrocytes become?
Neurones
What do astrocytes do if part of the CNS becomes damaged?
Lay down scar tissue
Try isolate damaged areas
Form glial scars
What forms if astrocytes become cancerous
Astrocytomas
Microglia function
Same as macrophages in PND
Defend neurones against pathogens
Important as neurones are post mitotic
What cells lie the ventricular system?
Ependyma
What shape are ependyma?
Cuboidal epithelial cells
What else do ependyma cover in the ventricles?
The CSF producing choroid plexus
