Nervous Tissue

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Nervous Tissue

• 2007

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Cellular Components of Nervous System

• Nerve Cells and Glia
• Nerve cells 100 billion cells in the body
• Glia 10 50 times as many as there are nerve
  cells
• Analogy Chocolate chip cookie where the glia
  are the dough and the neurons are the chips

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Neuroglia

• Provide structural and metabolic support for
  neurons
• Can divide and reproduce when injured (unlike
  neurons)
• Cannot conduct action potentials so cannot
  transmit information

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Schwann cell

• Major glial cell in the PNS
• Quick anatomy reminder CNS vs. PNS
• Produce myelin sheaths in the PNS Wraps cell
  membrane around the axon (50 times)
• Cytoplasm gets squished out (details on this in
  lab)
• Each Schwann cell wraps only one axon many cells
  in series along an axon

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Myelination
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Glia in the CNS

• 1. Oligodendrocytes form myelin in the CNS
• 2. Astrocytes provide structural support
• divide wildly when CNS is damaged,
  forming glial scars.
• - astrocytic end-feet form part of the
  blood-brain barrier
• types of astros
  
• a. Fibrous white matter of the CNS
• b. Protoplasmic grey matter of the CNS.
• 3. Microglia function as macrophages to
  remove dead or foreign tissue

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Ependymal Cells

• cuboidal epithelial cells that line the
  ventricles of the brain central canal of spinal
  cord.
• - have cilia to circulate CSF.

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Neurons

• Conduct action potentials nerve impulses thus
  transmit information
• Generally cannot divide when injured

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Components of a Neuron
dendrites cell body (soma) axon node of
Ranvier (if myelinated) Nerve terminals
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Parts of a Neuron

• Dendrites receive signals from other neurons
  branched, tapered, many per neuron.
• Cell body (soma perikaryon) nucleus large and
  euchromatic prominent nucleolus Nissl substance
  clumps of RER thus lots of protein synthesis.
• Axon output process of neuron one axon per
  neuron thinner than dendrites constant
  diameter no RER or ribosomes (so doesnt
  routinely stain)

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Node of Ranvier in myelinated axons teased
preparation
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Nervous System

• Central Nervous System (CNS)
• brain and spinal cord
• Peripheral Nervous System
• peripheral nerves, cranial nerves and
  their associated ganglia

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CNS brain spinal cord
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Development of Leukocytes
White matter
Gray matter
Dorsal root ganglion
(sensory neurons)
Promyelocyte
Eosinophilic Metamyelocyte
central canal
Myeloblast
Eosinophil
Eosinophilic myeolocyte
a-motor neuron
A
Motor end plate
SPINAL CORD
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Dorsal Root Ganglion
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DRG Nerve Cell Bodies with Euchromatic nucleus
and Prominent nucleolus
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Peripheral Nerve in Cross-section
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Neurovascular Bundle
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Nerve Fascicles in the Skin (longitudinal section)
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Node of Ranvier in myelinated axons
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Development of Leukocytes
White matter
Dorsal root ganglion (sensory)
Gray matter
Dorsal horn
Promyelocyte
Eosinophilic Metamyelocyte
central canal
interneuron
Myeloblast
Eosinophil
Eosinophilic myeolocyte
Ventral horn
a-motor neuron
Motor end plate
SPINAL CORD
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Motor End Plates
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Intestinal Wall
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Nerve cells of the Parasympathetic Ganglia in the
Intestinal Wall
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Nerve cells of the Parasympathetic Ganglia
Myenteric Plexus