11. glial cells IIII Flashcards
(19 cards)
What is the main focus of the lecture on oligodendrocytes and myelination?
The role of oligodendrocytes and Schwann cells in myelination and connections to disorders like multiple sclerosis.
How many axons does each oligodendrocyte myelinate?
Approximately 10 axons per cell.
How many axons does each Schwann cell myelinate?
Only one axon (1:1 ratio).
What triggers myelination in axons?
Axon diameter (>0.7μm in PNS, >0.2μm in CNS).
What is the G-ratio?
The ratio of axon diameter to myelin thickness, consistent at ~10 wraps per axon.
What types of Schwann cells exist?
- Myelinating Schwann cells
- Non-myelinating Schwann cells
- Perisynaptic Schwann cells
What are olfactory ensheathing cells (OECs)?
Cells found in the olfactory bulb that have properties of multiple glial types.
What is the primary composition of myelin?
70% lipids (mostly cholesterol, phospholipids, glycolipids) and 30% proteins.
What are the myelin proteins in the CNS?
- MBP (myelin basic protein)
- PLP (proteolipid protein)
What is the function of P0 protein in the PNS?
Serves a similar function to PLP.
What are the three components of the Nodes of Ranvier?
- Node
- Paranode
- Juxtaparanode
What is the role of sodium channels at the node?
They are anchored by NF186.
Fill in the blank: Myelination begins when OPCs differentiate into _______.
oligodendrocytes.
What is the autoimmune disorder that targets myelin components?
Multiple Sclerosis (MS).
What are the phases of pathophysiology in MS?
- Initial phase (immune-driven)
- Chronic phase (glial-driven)
What happens during the initial phase of MS?
Blood-brain barrier breakdown, auto-antibodies enter CNS, T-cells attack myelin.
What occurs during the chronic phase of MS?
Microglia become activated, produce reactive oxygen species, and astrocytes may form glial scars.
What can MRI distinguish in MS?
Active from inactive lesions.
True or False: Remyelination in MS returns to the original state.
False.
