electrical signaling 

chemical signaling

- soma (cell body)

- dendrites

- axon

- axon terminals (presynaptic endings)

receive information from sensory receptors or act as receptors 

&

send info to CNS

most common neuron

2 types:

- local

-projection 

glia = glue

- fill up space between neurons

Oligodendrocytes

Astrocytes

Microglia

Ependymal Cells

80% lipid & 20% protein 

- wrap themselves around the axons 

- insulates the axon

- form segments of myelin called internodes (Nodes of Ranvier)

- typically star shaped

- metabolic role & regulate extracellular ionic concentration

- respond to injury (gliotic scar)

-derive from monocytes

- after being activated by cytokines (after injury) they proliferate into specialized CNS macrophages (microglia)

- develop from neural tube 

- form the lining of the ventricular system

- special secretary cells that produce CSF (choroid plexus)

-myelin producing cells in PNS

- provides support and electrical insulation

sensory ganglia of cranial & spinal nerves

autonomic & enteric ganglia

schwann cells

melanocytes

adrenal chromaffin cells

pia/arachnoid membrances

cartilage & bone

Anterior = day 25

Posterior = day 27

prosencephalon

mesencephalon

rhombencephalon

telencephalon 

diencephalon

metencephalon = pons and cerebellum

myelencephalon = medulla

Neural Tube Defects

(NTDs)

• etiology of most congenital malformation involving the spinal cord stem from defective closure of neural tube
• NTDs affect the tissues overlying the spinal cord

• meninges protrude

• partial or complete failure of prosencephalon to separate
• failure of separation of telencephalon into 2 cerebral hemispheres
• 4th week
• associated with face abnormalities