L1.1.3.2.1: Major Regions of All Neurons

• MAJOR REGIONS OF ALL NEURONS

  • Cell body
  • Processes
• ● CELL BODY — metabolic center of the cell

  ○ Nucleus

  ■ Transparent and contains a large nucleolus

  ○ Nissl bodies

  ■ Rough endoplasmic reticulum; abundant in the cytoplasm

  ○ Neurofibrils

  ■ Intermediate filaments that maintain cell shape
• ● PROCESSES — armlike fibers that vary in length from microscopic to over 3 ft long, reaching from the lumbar region of the spine to the great toe

  ○ Dendrites

  ○ Axons
• ○ Dendrites — “Dendr” = tree

  ■ Conduct impulses toward the cell body

  ■ Neurons may have hundreds
• ○ Axons

  ■ Conduct impulses away from the cell body

  ■ Axon hillock - a cone-like region where axons arise from the cell body

  ■ Axon terminals - hundreds to thousands terminal ends; separated from the next neuron by a gap

  ■ Neurotransmitters - chemicals contained in tiny vesicles or membranous sacs

  ■ Synapse (syn = to clasp / join) - functional junction where an impulse passes from one neuron to another

  ■ Synaptic cleft - the gap at the synapse