Preparation for exam

Glial cells

Cells in the nervous system that support, nourish, and insulate neurons. Maintain the integrity of the brain and spinal cord by glueing neurons together. Sustain neurons by maintaining homeostasis of the extracellular fluid.
- Replace CT in CNS

Classification of Neuroglia (Supporting cells/ Glial cells)

CNS: Oligodendrocytes, Astrocytes, Microglia and Ependymal cells

PNS: Schwann cells, satellite cells

Oligodendrocytes

small and less branched than astrocytes. Wrap around the axons of the nerve cells to form myelin

Function of Oligodendrocytes

Synthesise myelin sheath of CNS axons. Forms multiple sheaths.

Astrocytes

A star-shaped cell. Most abundant. Proliferates after brain damage to form a scar.

Protoplasmic: present in grey matter. Envelopes neuronal body to form satellite cells

Fibrous: present in white matter. Perivascular feet on the wall of the capillaries to form a membrane

Function of Astrocytes

- Maintain the blood-brain barrier
- Regulates interstitial fluid composition
- Projections from the cell body grip and stablise neurons and capillaries.
- Regulate ion, nutrient, and dissolved gas concentrations
- Absorb and recycle neurotransmitters
- Form scar tissue after injury

Microglia

Smallest glial cells of CNS
Small, elongated, chromophilic nuclei with sparse polar process
Found in grey and white matter
Represent only 4% in normal circumstances

Functions of Microglia

Remove cell debris, wastes, and pathogens by phagocytosis (brain macrophages)

Ependymal cells

Epithelium-like cells, contain microvilli and cilia
Line ventricles and central canal (spinal cords)

Function of Ependymal cells

Lines the ventricles. Associated with capillaries in the ventricles to make up the choroid plexus and produce, circulate, and monitor CSF

Satellite cells

Attendants and servants of ganglionic neurons
PNS analogue to the CNS protoplasmic astrocyte
Found in both types of ganglia

Functions of Satellite cells

Surround and electrically insulates the neuron cell bodies in ganglia; regulate O2, CO2, nutrient, and neurotransmitter levels around neurons in ganglia

Schwann cells

Glial cells of the PNS
Surround all axons in PNS; responsible for myelination of peripheral axons; participate in repair process after injury