6 - Glial Cells: Form and Function

Vocabulary flashcards covering glial cell types, functions, and key concepts from the lecture notes.

Glia

Non-excitable cells of the nervous system that provide support to neurons; identified by morphology or cell-specific markers rather than electrophysiological activity.

Schwann cell

PNS glial cell that forms myelin around peripheral axons; supports regeneration in the PNS.

Oligodendrocyte

CNS glial cell that forms myelin around CNS axons; one oligodendrocyte can myelinate up to ~30 axons.

Endoneurial tube

Structure surrounding an axon in the PNS that guides and supports regrowth after injury.

Ependymal cells

Ciliated cells lining the walls of brain ventricles and the central canal of the spinal cord; produce and circulate cerebrospinal fluid (CSF).

CSF (cerebrospinal fluid)

Fluid produced in the ventricles that cushions the brain and provides nutrient and waste exchange.

Astrocyte

Largest and most numerous glial cell; stellate morphology with long processes; GFAP-positive; roles include neuronal development, brain architecture, and support of neurons.

GFAP (glial fibrillary acidic protein)

Intermediate filament protein used as a marker for astrocytes.

Astroglia stem cells

Astrocyte-derived progenitors that contribute to adult neurogenesis and gliogenesis.

Astrocytic syncitium

Network of astrocytes connected by gap junctions, enabling coordinated chemical/electrical coupling.

Gap junction

Intercellular channel that allows direct cytoplasmic exchange between cells; underpins the astrocytic syncitium.

K+ buffering

Astrocytes regulate extracellular potassium to prevent accumulation after neuronal firing.

ECF (extracellular fluid)

Fluid surrounding neurons; its ion balance is maintained by astrocytes.

Neurotransmitter transporters (astrocyte)

Astrocytic transporters that remove neurotransmitters from the synaptic cleft to prevent diffusion and protect the synapse.

Synaptic microenvironment

Local milieu around the synapse regulated by astrocytes, including ion balance and neurotransmitter clearance.

Neurovascular coupling

Link between neuronal activity and cerebral blood flow; astrocytes help regulate energy delivery and blood flow.

fMRI / BOLD

Functional MRI technique that detects blood-oxygen-level dependent changes as an indirect measure of neural activity.

Reactive astrogliosis

Astrocyte hypertrophy and proliferation in response to CNS injury, with increased GFAP and glial scar formation.

Glial scar

Barrier formed by reactive glia at injury sites that can inhibit axon regeneration.

Microglia

Smallest glial cell type; resident immune cells of the CNS; originate from bone marrow monocytes and migrate to the CNS; surveil the environment.

Resting microglia

Baseline surveillant state with ramified processes; not currently activated.

Activated microglia

Microglia responding to danger signals; become reactive and secrete inflammatory mediators.

Phagocytic microglia

Activated microglia that engulf and digest debris and dead cells during injury or disease.

CNS immune cell

Microglia function as the immune cells of the CNS, defending tissue and contributing to repair.

Neuroinflammation

Glial activation in CNS disorders; activated microglia can be neurotoxic; prolonged activation linked to neurodegeneration and ischemic injury; triggers astrocyte activation.