Neuroanatomy

neuron doctrine

braincells are independent from one another structurally, metabolically, and functionally; information is transmitted from one neuron to the next across tiny gaps

dendrites

many per neuron; tapes progressively toward end; no hillock-like region; no myelin sheath; often much shorter than axon

axon

one per neuron; has many terminal branches; uniform until start of terminal branching; hillock-like region; present myelin sheath; ranges from practically nonexistent to several meters long

input zone

the first part of a neuron, where neurons collect and process information, either from the environment or from other cells

integration zone

the second part of a neuron, where the decision to produce neural signal is made

conduction zone

the third part of a neuron, where information can be transmitted over great distances

output zone

the fourth part of a neuron, where the neuron transfers information to other cells

glial cell

protect and assist neurons

myelin

wraps around axon and speeds up

oligodendrocytes

form myelin sheath inside brain and spinal cord

schwan cells

provide myelin to neurons outside brain and spinal cord

nodes of ranvier

gaps between million where axon is exposed

astrocytes

start shaped cells with many process that stretch around and between neurons and, sometimes, blood vessels; secrete chemicals; help from outer membrane around the brain

microglial cell

tiny, mobile cells that remove debris from injured or dead cells

rostral (anterior)

front

caudal (posterior)

back

dorsal

up

ventral

down