Neural Tissue

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Neural Tissue

• The nervous system includes all the neural tissue
  in the body.

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Structure of the nervous system
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The Nervous System
Central Nervous System
Peripheral Nervous System
Afferent
Efferent
Brain
Spinal Cord
Somatic
Autonomic
Sympathetic
Parasympathetic
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Peripheral Nervous System

• Afferent - bring sensory
• Efferent - carry commands

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Efferent Division

• Somatic - skeletal muscle contractions
  (voluntary) involuntary reflexes
• Autonomic (visceral motor system) -Involuntary
  (smooth muscles, cardiac muscle
• glandular secretions)

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Autonomic Nervous System

• Parasympathetic - nonstressful
• rest digest
• Sympathetic
• stressful
• fight or flight

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Neuron

• Functional Structural unit of the nervous
  system

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dendrites
perikaryon
dendritic spines
dendrites
nucleus
telodendria
axon
Nissl bodies
mitochondria
axon hillock
Initial segment of axon
telodendria
axon
Golgi apparatus
synaptic terminals
neurofilaments
nucleus
nucleolus
Multipolar Neuron
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Vocabulary

• dendrites - typically highly branched, carry
  messages
• axon - propagates an electrical impulse away from
  the cell body
• initial segment - base of an axon

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Vocabulary cont.

• axon hillock - thickened region
• soma - cell body, houses organelles but lack
  centioles
• telodendria - fine extensions off the axon
• synaptic terminal - ends of the telodendria

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Structural Classification of Neurons

• anaxonic neuron
• bipolar neuron
• unipolar neuron
• multipolar neuron

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Functional Classification of Neurons

• Sensory neurons (afferent) - from sensory
  receptors
• to CNS
• somatic sensory neurons - monitor the outside
• world our position in it
• visceral sensory neurons - monitor internal
• conditions the status of the organs

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Sensory receptors

• proprioceptors
• interoceptors
• exteroceptors

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Sensory Receptors
Mechanoreceptors Thermoreceptors Nociceptors Chemo
receptors Osmoreceptors Photoreceptors

• Further broken down into

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Functional Classification of Neurons

• Motor Neurons (efferent) -
• carry instructions
• from
• the CNS to peripheral effectors

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Functional Classification of Neurons

• Interneurons (association) -
• outnumber all other types
• mostly in brain spinal cord
• situated between sensory motor
• neurons

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Ependymal Cells
line the central canal ventricles which house
the brain spinal cord, creates a barrier
between the Cerebral Spinal Fluid (CSF) and the
brain spinal cord
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NeuroglialCells
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Astrocytes

• Maintain the blood-brain barrier
• Create a 3-D framework for the CNS
• Repair damaged nerve tissue
• Guide neuron development
• Control the interstitial environment

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Oligodendrocytes

• Form the myelin sheath along the length
• of the axon
• myelin - increases the speed of the
• action potential along the axon
• myelin sheath - membrane wrapping
• around the axon
• internodes - area of the axon wrapped
• myelin (1 - 2 mm in length)
• nodes - small gaps (few micrometers)
• between internodes with no myelin
• white matter - CNS, areas with
• myelinated axons, high lipid content
• gray matter - areas containing neuron
• cell bodies, dendrites unmyelinated axons

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The Myelinated Axon
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Microglia

• least numerous
• cleanup by engulfing cellular debris, waste
  products pathogens