NERVOUS TISSUE PART 2

• Central Nervous System


  Consists of the Brain and the Spinal Cord
• Central Nervous System


  • Includes nerve tissues, connective tissues and blood vessels
• Functions of Central Nervous System

  To process and coordinate sensory data, motor commands, intelligence, memory, learning and emotion
• White Matter


  Contains groupings of myelinated axons, composed of capillaries, neuroglia and nerve fibers

  
• Gray Matter


  Contains neuron cell bodies, dendrites and synapses
• Dura mater


  • Dense connective tissue, separated from periosteum by epidural space, separated from arachnoid by subdural space

  
• Arachnoid mater


  Delicate impermeable membrane, made up of loose connective tissue devoid of blood vessels
• Pia mater


  Vascular membrane investing the brain and spinal cord, loose connective tissue with fine elastic fibers

  
• Blood-Brain Barrier


  Composed of endothelial cells, protects neurons and glia from toxins, infectious agents and other substances

  
• Choroid Plexus


  Highly vascularized tissue with prominent folds and villi, lined with Ependymal Cells, removes water from blood and releases CSF
• Cerebrum


  • Largest part of the brain, responsible for higher brain function: thought and action

  
• Layers of Cerebral Cortex

  • Molecular or Plexiform
  • External Granular
  • External Pyramidal
  • Internal Granular
  • Internal Pyramidal
  • Multiform or Polymorphic
• Pyramidal Cells

  Most neurons in Cerebral cortex, multipolar neuron with large vesicular nucleus, abundant Nissl Bodies, apical dendrites run towards most superficial part of Cerebral Cortex, axons run in the white matter

  
• Non-Pyramidal Cells


  • Stellate
  • Horizontal
  • Martinotti
• Cerebral medulla


  Inner part of Cerebrum, composed of white matter

  
• Cerebellum


  • Responsible for coordination with voluntary movement, balance and equilibrium, muscle tone
• Layers of Cerebellar Cortex


  • Molecular Layer
  • Purkinje Cell Layer
  • Granular Layer

  
• Cerebellar medulla


  Inner part of Cerebellum, composed of white matter

  
• Spinal Cord

  Central commissure joins anterior/ventral horns and posterior/dorsal horns, sends sensation from body to brain and returns motor commands from brain to parts of the body

  
• Peripheral Nervous System


  • Consists of all tissues outside Central Nervous System, including nerves, ganglia and nerve endings
• Peripheral Nerves


  Can be Myelinated or Unmyelinated, carry sensory information and motor commands in Peripheral Nervous System
• Categories of Peripheral Nerves

  • Cranial Nerves
  • Spinal Nerves

  
• Epineurium


  Outer tube-like layer of dense irregular Connective Tissue that covers nerves

  
• Perineurium


  Encases fascicles, thicker and more resistant than epineurium
• Endoneurium


  Loose Connective Tissue that encloses nerve fiber

  
• Neurolemma/Myelin Sheath


  Cytoplasmic covering produced by Schwann Cells (neurolemmocytes)

  
• Nodes of Ranvier


  Regular interval of myelin all over axon

  
• Ganglia


  Aggregations of nerve cell bodies outside Central Nervous System, ovoid structure encapsulated with dense Connective Tissue

  
• Types of Ganglia


  • Sensory (dorsal ganglia)
  • Autonomic (Sympathetic and Parasympathetic ganglia)
• Sensory Ganglia


  Found in dorsal roots of all spinal nerves and some cranial nerves, contain pseudounipolar nerve cells with spheroid shaped ganglion cells with large rounded nucleus

  
• Autonomic Ganglia


  Contain multipolar neurons with oval shaped ganglion cells and large oval nucleus