Biomedical Science - Neurons and Glial Cells; Myelination

Cells in the CNS and functions

• Oligodendrocytes - produce myelin sheath in the CNS

• Astrocyte - support, repair, homeostasis

• Ependymal cells - production and flow of cerebrospinal fluid(CSF), brain metabolism, and waste clearance

• Microglial cells - immune function PNS (Peripheral Nervous System)

• Satellite cells - support, repair homeostasis in the PNS

• Schwann cells - form the myelin sheath in the PNS

cell body

cytoplasm, nucleus, organelles

cell membrane

phospholipid bilayer around the whole cell

dendrite

receives incoming signals from other neurones

axon

carries outgoing signals to the axon terminal

synapse

communicates with dendrites on other neurons

myelin sheath

-a protective, fatty, insulating layer

-wraps around the axon of many neurons in the NS

-The insulation makes impulses travel faster and more efficiently along the axon

-myelin wraps in segments, creating gaps called nodes of ranvier

-myelin is formed by nearby neuroglial cells

-wrap around axon

-their phospholipid bilayer membranes are lipid, creating the lipid sheath known as myelin

-in CNS, myelin is formed by oligodendrocytes

nodes of Ranvier

nodes between myelinated regions

multiple sclerosis

-the immune system attacks the layer that surrounds and protects the nerves called the myelin sheath

white matter

myelinated

grey matter

unmyelinated

sensory neurons functions

carry info from the periphery to CNS, known as afferent neurons

motor neurons functions

carry info from CNS to muscles and glands - cause an effect, known as efferent neurons

relay/interneurons functions

form links between other neurons in CNS

structure of a nerve (only seen in PNS)

a nerve is made of bundles of individual neuron cells, with blood vessels and connective tissue

Several layers: endoneurium, perineurium, epineurium