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Neurons - Coggle Diagram
Neurons
:star: GLIA
:star: Oligodendrocytes:
produces myelin cells of CNS, myelin - insulates axon segments, enables rapid nerve conduction, myelin sheath segments interrupted by nodes of Ranvier = saltatory conduction, provides metabolic support for axons = lactate transport
Only found in vertebrates
**oligodendrocytes are CNS, Schwann cells are PNS
:star: Myelin Sheath:
formed by wrapping of axons by oligodendrocyte processes, highly compacted - 70% lipid, 30% protein
Myelin specific proteins can be used as 'markers'
:star: Microglia:
resident immune cells of CNS, originate from yolk sac progenitors that migrate into CNS
'Resting' state, highly ramified, motile processes survey environment
When activated - retract processes, become 'amoeboid' and motile
Proliferate at sites of injury - phagocytic
Functions: immune surveillance, phagocytosis - debris/ microbes, synaptic plasticity - pruning of spines
:star: Astrocytes: star-like cells, most numerous glial cells in CNS, highly heterogenous, common 'marker' glial fibrillary acidic protein (GFAP)
Functions: structural - define brain micro-architecture, envelope synapses - buffer K+, glutamate etc, metabolic support, neurovascular coupling - changes in cerebral blood flow in response to neural activity, proliferate in disease = astrocytosis/ gliosis
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:star: Neurones: specialised for electrical signalling, inputs via dendrites, action potentials spread along axon from axon hillock, mainly formed during embryonic development
Tissue sections
H&E - haemotoxylin, stains nucleic acids blue, eosin stains proteins red
Neural communication:
Chemical synapses - via ntm
Electrical synpases - via direct flow of ions, enable synchronised electrical activity
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:star: Spines and Neural Plasticity:
Neural plasticity - changes in neuronal/ synaptic structure and function in response to neural actiity
Spines - dynamic structure so variable in number, size, composition + spine remodelling linked to neural activity
:star: Neuronal Heterogeneity:
Neurons differ in size, morphology, ntm content, electrical properties
:star: Blood-Brain Barrier:
formed by endothelial cell tight junctions, basement membrane, astrocyte end feet and pericytes
Sensitive to inflammation, hypertension, trauma, ischaemia