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33 Cards in this Set
- Front
- Back
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What is the alimentary canal?
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-Continuation of the oral cavity
-Tubular portion of the digestive tract -Food is churned, liquefied and digested -Nutritional elements and water are absorbed -Indigestible components eliminated -Approximately 9 meters long -Subdivided into morphologically recognized regions: Esophagus, Stomach (cardiac, fundus, body, pylorus), Small intestine (duodenum, jejunum, ileum), Large intestine (cecum, colon, rectum, anal canal, appendix) |
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What are the 4 tunics or coats of the alimentary canal going for inside to out?
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1. Mucosa
2. Submucosa 3. Muscularis externa 4. Adventitia |
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What are the different layers of the mucosa of the alimentary canal?
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- Epithelium
- Lamina Propria (loose CT, glands, vascular, lymph nodules) -Muscularis mucosae (inner circular, outer longitudinal) |
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What are the different components of the submucosa of the alimentary canal?
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- Irregular, fibroelastic CT
- Vascular - Glands in esophagus and duodenum -Meissners submucosal plexus |
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What are the different components of the muscularis externa of the alimentary canal?
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- Inner circular
- Outer longitudinal - Auerbach's plexus |
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What are the different characteristics of the serosa/adventitia of the alimentary canal?
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-Thin connective tissue
-Serosa if intraperitoneal -Adventitia if retroperitoneal |
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What are the two source of enteric innervation?
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1. Autonomic nervous system: Sympathetic and parasympathetic
2. Enteric nervous system: Meissner's and Auerbach's plexi |
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What are the functions of Meissner's plexus?
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Secretory function, mucosal movement, regulation of blood flow
Attentive to focal local conditions |
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What are the functions of Auerbach's plexus?
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Peristalsis
Attentive to local conditions along the entire length of the digestive tract |
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What are the functions of the ANS components of enteric innervation?
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Parasympathetic:
-Stimulates peristalsis -Inhibits sphincter muscles -Triggers secretory activity Sympathetic -Inhibit peristalsis -Activates sphincter muscles |
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What does the mucosa of the esophagus look like histologically?
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The esophageal mucosa is composed of a stratified squamous epithelium w/ langerhans cells, fiberoelastic lamina propria, and a smooth muscle layer that is the longitudinally disposed muscularis mucosae.
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What are the characteristics of the lamina propria of the esophagus?
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The lamina propria is unremarkable. It houses esophageal cardiac glands, which are located in two regions of the esophagus, one cluster near the pharynx and the other near its juncture with the stomach.
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What are the characteristics of the muscularis mucosae of the esophagus?
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The muscularis mucosae is unusual in that it consists of only a single layer of longitudinally oreinted smooth muscle fibers that become thicker in the vicinity of the stomach
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What are the characteristics of the submucosa of the esophagus?
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The submucosa of the esophagus is composed of a dense, fibroelastic connective tissue, which houses the esophageal glands proper. It has two cell types associated with it, Mucous cells and serous cells and contains the submucosal nerve plexus.
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What are the charcteristics of the mucous cells found in the submucosa of the esophagus?
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Mucous cells have basally located, flattened nuclei and apical accumulations of mucus filled secretory granules.
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What are the characteristics of the serous cells found in the submucosa of the esophagus?
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Serous cells, with round centrally placed nuclei. the secretory granules of these cells contain the proenzyme pepsinogen and the antibacterial agent lysozyme.
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What are the characteristics of the muscularis externa and adventitia of the esophagus?
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-Two layers, inner circular and outer longitudinal
-Composed of both skeletal and smooth muscle fibers -Auerbach's plexus -Covered by an adventitia until it pierces the diaphragm, after which it is covered by a serosa |
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What types of sphincters does the esophagus have and what are they called?
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-Does not have an anatomical sphincter but has two physiologic sphincters
1. Pharyngoesophageal 2.Gastroesophageal |
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What is the propulsion of the bolus in the esophagus?
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50 mm/sec
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What are the characteristics of the stomach?
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-Most dilated region of digestive tract
-Can hold about 1500 ml of food -Empties via pyloric valve to duodenum -Liquifies food through enzymatic digestions using pepsin, renin, gastric lipase, paracrine hormones -Gross structure provides identification of 4 regions: cardia, fundus, body, pylorus -Histologically the fundus and body are alike -Epithelium invaginates forming gastric pits or foveolae into which 5-7 gastric glands may empty |
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What are the different regions of the mucosa of the stomach?
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-Epithelium - simple columnar (surface lining cells, regenerative cells)
-Lamina proria - contains glands (named for region as each are different) -Muscularis mucosa |
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What are the three distinct regions of the fundic glands?
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1. Isthums
2. Neck 3. Base (fundus) |
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What are the 6 cell types of the fundic glands?
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1. Surface lining
2. Parietal 3. Regenerative 4. Mucous Neck 5. Chief (zymogenic) 6. DNES |
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What are the 3 layers of muscularis mucosae of the stomach?
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1. Inner circular
2. Outer longitudinal 3. Outermost circular |
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What are the characteristics of the submucosa of the stomach?
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-Rich vascular and lymphatic networks
-CT proper compliment of cell types -Meissner's submucosal plexus |
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What are the 3 layers of the muscularis external of the stomach?
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1. Inner oblique
2. Middle circular 3. Outer longitudinal |
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What is are the characteristics of the adventitia/serosa of the stomach?
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- Nothing remarkable
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What are the characteristics of the small intestine?
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-7m in length (longest region of the digestive tube)
-Villi -Microvilli -3 Regions: Duodenum, Jejunum, Ileum -Plicae circulares (valves of Kerckring) |
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What are the 4 layers of the small intestine?
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-Mucosa
-Submucosa -Muscularis externa -Adventitia/Serosa |
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What are the layers of the mucosa of the small intestine?
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-Epithelium: simple columnar, 6 cell types (absorptive, goblet, DNES, regenerative, Paneth, M-cells)
-Lamina propria: Crypts of lieburkuhn -Muscularis mucosa |
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What is found in the submucosa of the small intestine?
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Brunner's glands in the duodenum
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What are the 4 regions of the large intestine:
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1. Caecum - (appendix)
2. Colon - ascending, transverse, descending, sigmoid 3. Rectum 4. Anus |
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What are the characteristics of the large intestine?
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- No villi
- Crypts of Lieberkuhn - No paneth cells - Increases in number of goblet cells although surface absorptive cells are the most numerous -Epithelial turnover every 6-7 days -Lamina propria, muscularis mucosa, and submucosa unremarkable -Muscularis external has outer longitudinal layer gathered into 3 ribbons called taeniae coli, the continuous tone of which causes the LI to "pucker" forming sacculations called haustra coli |
