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fntpric Nervous System

GASTROINTESTINAL PHYSIOLOGY

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Myenteric plexus (cross section; bematoxylin-eosin, x 200)

Sultserous plexus

Longitudinal

intramuscul;

plexus

Myenteric

(Auerbach‘s)

plexus

Myenteric plexus (parallel section; methylene bluo, X 200}

Submucosal ploxus (longitudinal section: hematoxylin-eosin, X200)

Lumen

Mucosa and mucosal glands Musculans mucosae Brunner's glands Submucosa Circular muscle Intermuscular stroma Longitudinal muscle Subserous connectiye tissue Visceral peritoneum

Figurę 7.4 Enteric Nervous System-

The intrinsic innervation ot the smali and large intestine is by the enteric nervous system, comprised ot a neural nelwork in the myen-teric. (Auerbach's> and submucosal (MeissnePs) plexuses. Tlie myenteric plexus is primarily involved in controlling motility, whereas the submucosal plexus primarily Controls tluid secretion and absorptión. Neurons of this system interconnect with one another and with the neurónal processes ot the autonomie nervous system. Iransmitter sul>-stances (morę than 20 differenl ones have becn identified) such as

ACh (acetylcholine), suhstance P. S-HT (serotonin), VIP <vasoactive intestinal peptide), NO (nitric oxidel, SomałOStatin, and a host o< other peptides are commonly found in the intrinsic neurons. For exampie. ACh and substance P are excitatory to smooth mu** W*, wherras V7P and NO are inhibitory. Optimal tum tioning ot the Gl tract rcqurw coordinated interactions between a host ot endocrine. paraem*. and neurocrine substances.

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