sanjeev ghai, sanjeev ghei

8/11/2019 Sanjeev ghai, Sanjeev ghei

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Anatomical subdivisions of NS

Made up of neurons

and neuroglia cells



Functional Overview of NS

CNS

Integration,

processing and

coordination of

sensory data andmotor 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

cellsLining of ventricles & central canal

Some regions ciliated

Some specialized to produce CSF



Schwann Cells

and Peripheral Axons

myelinated

Responsible for

myelination, but

surround all peripheral

axons!

Involved in repair

mechanism after injury

Wallerian Degeneration



Structural Neuron Classification

Anaxonic

In CNS

UnipolarAlso called

pseudounipolarSensory neurons

Axon hillock

See fig. 13-10



Structural Neuron Classification cont. . .

BipolarUnmyelinated

Rare, but importantin special senses

MultipolarMost common

All motor neurons



Functional Neuron Classification

1) somatic vs.

visceral sensory

or afferent

monitoring of ?

2) somatic vs.

visceral motor

or efferentcarry instructions to ?

3) Inter- or

association neurons



Synapse

Site of communication between two nervecells or nerve cell and effector cell

neuro-effector junctions

(example?)

Electrical vs.

chemical synapses



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

sanjeev ghai, sanjeev ghei

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