Glial Cells, Mylination, and Regeneration

neuroglia (glial cells)

protect and nourish neurons

found in CNS and PNS

smaller, more numerous

capable of mitosis

brain tumors more likely via glial cells

astrocytes (CNS)

paravascular feet that shield vessels (blood brain barrier) preventing toxic substances to going to brain

most abundant glial cells

ependymal cells (CNS)

ciliated cuboidal epithelial cells that line ventricles of brain and central canal of spinal cord

help produce CSF

microglial cells (CNS)

engulf debris

oligodendrocytes (CNS)

CNS axons only

wrap themselves around the axons

produce myelin

satellite cells (PNS)

regulate fluid composition around neuron cell bodies

monitor what goes around

neurolemmocytes or schwann cells (PNS)

form myelin sheaths

play an important role in regeneration

myelination

wrapping axon with myelin sheath to electrically insulate it

made of fatty substance that protects and speeds up communication

saltatory conduction

an impulse jumps from one neurofibril node to another

HAS to have myelin sheath

continuous conduction

impulses propagated by unmyelinated axons

nerve

bundle of cable-like parallel axons

endonerium

surrounds each cell/axon

perineurium

surrounds each fascicle

epineurium

surrounds whole nerve

synapse

specialized junctions between two neurons, a neuron and muscle cell or gland cell

presynaptic neuron

signal sender; synaptic knobs at axon endings for sending signals

synaptic cleft

synapse

postsynaptic neuron

signal receiver; after synapse

neuronal pools

neurons grouped into different patterns

makes synapses difficult

multiple sclerosis

autoimmune disorder; attacks myelin and breaks it down. interferes with communication

amyotrophic lateral sclerosis (ALS)

neurodegenerative disease affecting motor neurons

Nervous systems breaks down motor neurons causing muscle weakness, atrophy, and spastic paralysis