Neural Tissue PPT

June 15, 2012 | By | Reply More

Neural Tissue PPT

Made up of neurons and neuroglia cells

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.
Cellular Organization of Neural Tissue

Two cell types:

1.Neurons
2.Neuroglia
Schwann cells
Satellite cells
Astrocytes
Oligodendrocytes
Microglial cells
Ependymal cells
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

Structural Neuron Classification

Anaxonic

In CNS

Unipolar

Also called pseudounipolar

Sensory neurons

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

Chem. Synapse Structure

1.Axon terminal of presynaptic cell
2.Synaptic cleft
3.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

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