glial cells and axon myelination lecture one part three

glial cells in pns

satellite cells & neurolemmocytes

satellite cells

surround neuron cell bodies in the spinal ganglia

protect the cell bodies by regulating nutrient exchange and waste removal

neurolemmocytes

myelinate axons in pns and help regenerate damaged pns axons

myelin

protective covering around an axon

they insulate axons and produce faster nerve impulses

glial cells in cns

astrocytes, oligodendrocytes, microglia, ependymal cells

astrocytes

regulate transfer of materials from blood to brain - help the 'blood brain barrier', make vessels less 'leaky'

oligodendrocytes

myelinate axons in cns

microglia

phagocytize (eat and remove) damaged neurons

ependymal cells

line central canal and ventricles - help circulate csf

myelination

the process of wrapping an axon with myelin

insulates axon and produces faster nerve impulses

myelination procedure in pns

1. neurolemmocyte wraps around a 1 mm portion of an axon

2. cytoplasm and nucleus of a neurolemmocyte are squeezed to the outside

3. inner successive layers of neurolemmocyte cell membrane make up the myelin sheath

neurofibril nodes

seperate neurolemmocytes

where nerve impulses are generated

myelination procedure in cns

1. oligodendrocyte myelinates 1mm portion of many axons

TRUE OR FALSE: myelinated axons produce faster nerve impulses than unmyelinated axons

TRUE