Download BN08 neurons & glia

Neurons
& Glia
Lesson 8
Nature of the Nervous System
Golgi & Cajal shared
Nobel Prize (1906)
 Reticular Theory
Camillo Golgi
 The Neuron Doctrine
Santiago Ramon y
Cajal
Silver chromate
Golgi Stain ~

Neurons
Basic functional unit of N.S.
 Specialized cell
 All cells have same basic
properties
 Regulation of behavior
 Information processing
 Transmits
 Integrates
 Stores ~


Dendrites & Soma
 Receives & Integrates information
 electrical signal within ~

Axon carries information away from soma
 Electrical signal within
 Axon terminal releases chemical message ~
Neuron Classification
By function (connections)
By Morphology
# of neurites
 Multipolar, bipolar, monopolar
 By Dendrite Structure
 Pyramidal
 Stellate
 Dendritic Spines
 Spiny or Aspinous ~

By morphology (# of neurites)
Multipolar
Bipolar
Unipolar
By Axon Diameter
Sensory afferents
 Size: largest  smallest
 Aa, Ab, Ad, C
 C: small, unmyelinated
 pain & temperature
 Aa:
 not associated with skin receptors
 proprioceptors in muscle ~

Primary Afferents

Conduction speed
 larger faster &
 myelinated faster~
Other Classification Schemes
Axon length
 Golgi Type I - long
 Golgi Type II - short (local signaling)
 Chemistry
 neurotransmitter released
 e.g., cholinergic, dopaminergic ~

Neurons vs. Nerves
Neurons - cells
 microscopic
 Nerves - bundles
of axons
 seen with
naked eye ~

Glia
Astrocytes
Provide physical support
 Regulating chemical content of
extracellular fluid
 localizes neurotransmitters
 K+ concentration
 Blood-brain Barrier ~

Blood-Brain Barrier
Typical
Capillary
astrocytes
Brain
Capillary
BBB: Function
Maintains stable brain environment
 large fluctuations in periphery
 Barrier
 to poisons
 neurotransmitters & other
chemicals
 Regulates nutrient supplies
 glucose levels
 active transport ~

Myelin
Wrap around axon
 Saltatory Conduction
 faster transmission
 CNS: oligodendroglia
or oligodendrocytes
 PNS: Schwann cells ~

Other non-neuronal cells
Microglia
 phagocytosis
 immune-like function
 Ependymal cells
 line walls of ventricles
 develop from radial glia ~
