Transcript Nervous System

INTRODUCTION TO THE
NERVOUS SYSTEM
Functions of the Nervous System
Organization of the Nervous System
Nervous Tissue: Support Cells &
Neurons


Support cells in the CNS are grouped
together as “neuroglia”
Function: to support, insulate, and
protect neurons
1. Astrocyte
2. Microglial Cells
3. Ependymal Cells
4. Oligodendrocytes
Anatomy of a Neuron
Structure of Schwann Cells
Where are the Neuron Cell Bodies?

Most neuron cell bodies are found in the central
nervous system
 Gray
matter—cell bodies in clusters called “nuclei”
 White matter – dense collections of myelinated fibers
called “tracts”

Ganglia—collections of cell bodies in the
peripheral nervous system
Neuron Classification
Functional Classification of Neurons
Free nerve
endings
Meissner’s
corpuscles
Proprioceptors
Golgi tendon
Lamellar
corpuscles
Muscle spindle
Structural Classification of Neurons

Multipolar neurons—many extensions from the cell
body
Structural Classification of Neurons

Bipolar neurons—one axon and one dendrite
Structural Classification of Neurons

Unipolar neurons—have a short single process
leaving the cell body
Nerve Impulses
Also known as “Action Potentials”
 All-or-Nothing
 If the action potential starts, it is
propagated (carried) over the entire
axon
 Impulses travel faster when fibers have a
myelin sheath

What is an “Action Potential”?

It starts with a neuron at “resting potential”
What is an “Action Potential”?

A stimulus causes Na+ to come in through
a small patch of membrane
What is an “Action Potential”?

The action potential “propagates”
What Happens at the End of the
Neuron?

There is transmission of a signal across the
synapse
Axon
Axon of
transmitting terminal
neuron
Vesicles
Action
potential
arrives
Synaptic
cleft
Receiving
neuron
Synapse
What Happens at the End of the
Neuron?
How Does the Neuron Get Back to
“Normal”?

Through the process of “repolarization”