Transcript Neural Tissue

Made up of neurons
and neuroglia cells
Anatomical subdivisions of NS
Functional Overview of NS
CNS
 Integration,
processing and
coordination of
sensory data and
motor commands

Higher functions
PNS
1.
Sensory or afferent division
with sensory neurons.
Brings sensory info to CNS.
Begins as receptors, ends
in?
2.
Motor or efferent division
with motor neurons.
Brings motor commands to
peripheral tissue.
Ends at effector cells.
Peripheral Nervous System
Cellular Organization of Neural Tissue
Two cell types:
1. Neurons
2.
Neuroglia






Schwann cells
Satellite cells
Astrocytes
Oligodendrocytes
Microglial cells
Ependymal cells
See fig. 13-5
Compare to fig. 14-4
General Neuron Structure




Cell body or Soma with Perikaryon
Dendrites
Axon with axon hillock
Synaptic terminals
Astrocytes: largest & most numerous
Function:
BBB
structural framework & repairs
regulation of ions, nutrients, gases
Oligodendrocyte
Smaller than astrocyte
Produce myelin in CNS (white matter vs. gray matter!)
Myelin = ?
Microglia cells

Smallest

Phagocytosis of ?

 # during infection
or injury
Ependymal
cells
Lining of ventricles & central canal
Some regions ciliated
Some specialized to produce CSF
Schwann Cells
and Peripheral Axons
Responsible for
myelination, but
surround all peripheral
axons!
Involved in repair
mechanism after injury
Wallerian Degeneration
myelinated
Structural Neuron Classification
Axon hillock
Anaxonic
In CNS
Unipolar
Also called
pseudounipolar
Sensory neurons
See fig. 13-10
Structural Neuron Classification cont. . .
Bipolar
Unmyelinated
Rare, but important
in special senses
Multipolar
Most common
All motor neurons
Functional Neuron Classification
1) somatic vs.
visceral sensory
or afferent
monitoring of ?
2) somatic vs.
visceral motor or
efferent
carry instructions to ?
3) Inter- or
association neurons
Synapse
Site of communication between two nerve
cells or nerve cell and effector cell
neuro-effector junctions
(example?)
Electrical vs.
chemical synapses
Chemical Synapse vs. Electrical Synapse
Space between two cells
Signal transduction via NT
Most common
Direct physical contact between
cells = gap junctions
Direct signal transduction
Rare, but occurs in CNS and heart
Chem.
Synapse
Structure
1.
2.
3.
Axon terminal of presynaptic cell
Synaptic cleft
Dendrite or cell body of postsynaptic cell
Neuron Organization

Divergence - One neuron synapses with several,
effectively "spreading the word".

Convergence - Several neurons synapse with a single
neuron, concentrating the input.

Serial processing - step-wise, sequential

Parallel processing - simultaneous processing of
different information
Anatomical Organizatin of NS
Collections of cell bodies - ganglion in PNS, center or
nucleus in CNS
Bundles of axons - tracts in CNS, nerves in PNS
“White” = myelinated axons, both nerves and tracts
“Gray” = non-myelinated material, dendrites,
synapses and cell bodies as well as nonmyelinated
axons. In CNS – nucleus; in PNS - ganglia
Compare to fig. 13-15