Divisions of the Nervous system

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Divisions of the Nervous system

• CNS (Central Nervous system)
• Brain and spinal cord
• PNS (Peripheral Nervous system)
• Neural tissue outside CNS
• Afferent division brings sensory information from
  receptors
• Efferent division carries motor commands to
  effectors
• Efferent division includes somatic nervous system
  and autonomic nervous system

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Figure 12.1 Functional Overview of the Nervous
System
Figure 12.1
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Neuron classification

• Anatomical
• Anaxonic
• Unipolar
• Bipolar
• Multipolar

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Figure 12.4 A Structural Classification of
Neurons
Figure 12.4
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Functional

• Sensory neurons
• deliver information from exteroceptors,
  interoceptors, or proprioceptors
• Motor neurons
• Form the efferent division of the PNS
• Interneurons (association neurons)
• Located entirely within the CNS
• Distribute sensory input and coordinate motor
  output

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Figure 12.5 A Functional Classification of
Neurons
Figure 12.5
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Neuroglia of the Central Nervous System

• Four types of neuroglia in the CNS
• Ependymal cells
• Related to cerebrospinal fluid
• Astrocytes
• Largest and most numerous
• Oligodendrocytes
• Myelination of CNS axons
• Microglia
• Phagocytic cells

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Figure 12.6 An Introduction to Neuroglia
Figure 12.6
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Figure 12.7 Neuroglia in the CNS
Figure 12.7a
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Axon classification

• Type A fibers
• Type B fibers
• Type C fibers
• Based on diameter, myelination and propagation
  speed