2.1 GI tract Neural Control

• What is the name of the nervous system in the gastrointestinal tract?

  Enteric nervous system
• Where does the enteric nervous system lie?

  In the wall of the gut
• What is the approximate number of neurons in the enteric nervous system?

  About 100 million
• How does the number of neurons in the enteric nervous system compare to the spinal cord?

  Nearly equal to the spinal cord
• What functions does the enteric nervous system control?

  Gastrointestinal movements and secretion
• What are the two main plexuses of the enteric nervous system?

  • Myenteric plexus (Auerbach’s plexus)
  • Submucosal plexus (Meissner’s plexus)
• Where is the myenteric plexus located?

  Between the longitudinal and circular muscle layers
• What does the myenteric plexus primarily control?

  Gastrointestinal movements
• What does the submucosal plexus primarily control?

  Gastrointestinal secretion and local blood flow
• What type of fibers connect to both the myenteric and submucosal plexuses?

  Extrinsic sympathetic and parasympathetic fibers
• Can the enteric nervous system function independently of extrinsic nerves?

  Yes, it can function independently
• How can extrinsic nerves affect gastrointestinal functions?

  They can enhance or inhibit functions
• Where do sensory nerve endings originate in the gastrointestinal system?

  In the gastrointestinal epithelium or gut wall
• What do sensory nerves send afferent fibers to?

  Both plexuses, prevertebral ganglia, spinal cord, brain stem
• What can sensory nerves elicit within the gut wall?

  Local reflexes
• What other reflexes can sensory nerves relay to the gut?

  Reflexes from prevertebral ganglia or brain