Glia Flashcards
CNS contains
- brain
- spinal cord
PNS contains
- afferent division
- efferent divison
afferent division
sensory
afferent contains
cranial nerves
afferent means
going into
efferent division
motor
efferent contains
spinal nerves
efferent means
exiting
neurons
“functional unit’ of nervous system
glia (neuroglia)
“nerve glue”
- supports cells
glia functions/features
- > 90% of cells in CNS –> 50% by volume
- surround neurons and physically and metabolically support them
- mitotic
glia different from neurons
- no axons
- local potentials
- electrical (gap) junctions
- RMP more negative
- -> -90 mV = more permeable to K+
CNS glia cells:
- astrocytes
- oligodendrocytes
- microglia
- ependymal cells
astrocytes
most abundant
astrocytes function
- form blood brain barrier (BBB)
- nutrient and waste transfer –> require ECF
- form scaffolding
oligodendrocytes function
form myelin sheath around CNS axons (about 40 axons per cell)
microglia
macrophages of CNS
- non-neuronal precursor —> come from bone marrow
microglia function
clean up cellular debris and bacteria
ependymal cells function
- line ventricles of CNS
- produce cerebrospinal fluid (CSF)
PNS glia cells:
Schwann cells
Schwann cells function
form myelin sheath around axons in PNS –> only one axon per Schwann cell
myelin
- 80% lipid
- 20% protein
myelin function
insulates axon to increase conduction velocity
- alters cable properties of neuron
- decreases Cm and increases Rm
