Tunics of the GI tract Flashcards
Digestion function
-process/digest food
-get rid of non-digestive foods
-absorb nutrients
-mechanical and chemical digestion
-make vitamin K
Mucosa of the GI tract
-innermost layer exposed to lumen
-secretes mucus
-contains 3 regions: epithelium, lamina propria, muscularis mucosae
epithelium of mucosal region
-broken into stratified squamous found in oral cavity, esophagus, and anal canal and simple columnar found in stomach and intestines
lamina propria of mucosa region
-basement membrane
-composed of areolar connective tissue
muscularis mucosae of the mucosa region
-smooth muscle tissue
submucosa of the GI tract
-made of dense irregular connective tissue for support
-contains blood vessels, lymphatic vessels, lymph nodes, exocrine glands for mucus secretion, submucosal (Meissner’s) plexus
what is the submucosal (Meissner’s) plexus
-where parasympathetic ganglia, and neurons are located
Muscularis Externa of the GI tract
-source for peristalsis
-contain smooth (some skeletal) muscle tissues running in layers: oblique (unique to stomach), circular (inner), longitudinal (outer)
-contains submyenteric (Auerbach’s) plexus
What is the submyenteric (Auerbach’s) plexus
-where parasympathetic ganglia and neurons are located
-between circular and longitudinal layers
serosa or adventitia of the GI tract
-also known as visceral peritoneum
-a continuation of the mesenteries: areolar connective tissue, and mesothelium (made of simple squamous epithelium)
-name depends on location in GI tract
Serosa of the GI tract location
-lower portion of esophagus to sigmoid colon
adventitia of the GI tract location
-more fibrous
-oral cavity, pharynx, most of esophagus, rectum
Together the submucosal (Meissner’s) and submyenteric (Auerbach’s) plexuses…
-collectively make up the enteric division of the autonomic nervous system. There are approximately 100 million neurons located within the gut that regulate peristalsis
