Term
| What are the four general layers of the digestive tract organs (esophagus, stomach, small bowel, colon)? |
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Definition
Mucosa
submucosa
muscularis externa
adventitia/serosa |
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Term
| What are the 3 components of the mucosa? |
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Definition
| epithelium, lamina propria, muscularis mucosa |
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Term
| What are the components of the submucosal layer? |
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Definition
| connective tissue, vessels, and Meissners plexuses, sometimes mucous glands |
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Term
| What are the components of the Muscularis externa? |
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Definition
| 2-3 layers of smooth muscle (plus skeletal muscle in esophagus), myenteric (Auerbach) plexus in between muscle layers |
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Term
| Where is Meissner's plexus? What is its function? |
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Definition
In the submucosa. Meissner's = submucosal plexus
Function = innervate cells in the epithelial layer and the smooth muscle of the muscularis mucosae. Meissner's receives only parasympathetic input. |
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Term
| Where is Auerbach's plexus? What is its function? |
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Definition
Between inner circular and outer longitudinal muscle layers of the muscularis externa. Auerbach's = myenteric plexus.
Function = provides motor innervation to both layers of the tunica muscularis, having both parasympathetic and sympathetic input. |
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Term
| What type of epithelium comprises the mucosa of the esophagus? |
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Definition
| non-keratinizing stratified squamous |
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Term
| What type of epithelium comprises the mucosa of the stomach? |
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Definition
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Term
| What type of epithelium comprises the mucosa of the small bowel? |
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Definition
| The mucosa of the small intestine is characterized by evagination into plicae and villi, which increase the surface area for nutrient absorption, and by short tubular invaginations, the crypts, which provide a protected site for stem cells. The mucosa of the small intestine is lined by a simple columnar epithelium which consists primarily of absorptive cells (enterocytes), with scattered goblet cells and occasional enteroendocrine cells. In crypts, the epithelium also includes Paneth cells and stem cells. |
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Term
| What type of epithelium comprises the mucosa of the appendix, colon and anal canal? |
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Definition
The mucosa of the appendix, colon, and rectum has a simple columnar epithelium shaped into straight tubular crypts. There are no villi.
appendix -- more lymph nodules
colon -- lined with serosa (intraperitoneal)
rectum -- lined with adventitia (retroperitoneal)
anal canal -- transition where the characteristics of the colon and rectal mucosa change to those of skin. |
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Term
| What is the function of submucosal glands in the esophagus? |
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Definition
| Increased mucous glands at lower esophagus (GE junction) to protect esophagus from gastric juices |
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Term
| What are the four parts of the stomach? |
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Definition
1. cardia - first section; separate from esophagus by cardiac sphincter. Glands contain mucus-secreting cells, stem cells, enteroendocrine, and occasional parietal cells
2. fundus and 3. body
largest portion. Fundic glands contain parietal cells and chief cells with some stem cells, mucous cells and enteroendocrine cells
4. pylorus - lower end that connects to duodenum; ends at pyloric sphincter. Glands primarily mucus-secreting cells and two special endocrine cells: gastrin-secreting (G cells) and somatostatin-secreting cells (D-cells) |
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Term
| What is the function of gastric pits? |
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Definition
| Gastric pits are indentations in the stomach which denote entrances to the tubular shaped gastric glands. Gastric juice (HCl, pepsinogen, mucus) is secreted from gastric glands, which are located in narrow tube like structures called gastric pits. |
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Term
| What substances are secreted from parietal cells? chief cells? |
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Definition
parietal cells secrete HCl and IF
chief cells secrete zymogen granules containing pepsinogen |
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Term
| Which part of the small intestine can be identified by villi and Brunner glands (mucus-secreting)? |
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Definition
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Term
| Which part of the small intestine can be identified by long villi and increased goblet cells but no Brunner glands or Peyer patches? |
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Definition
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Term
| Which part of the small intestine can be identified by short villi, many goblet cells, and lymphatic nodules in the submucosa called Peyer patches? |
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Definition
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Term
| What are the Crypts (Glands) of Lieberkuhn? |
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Definition
An intestinal gland in lamina propria of the small intestine and colon that opens into the mucosa at the base of villi.
Paneth cells with pink granules at the base of the crypts secrete lysozymes, tumor necrosis factor-alpha, and defensins. |
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Term
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Definition
| three separate longitudinal ribbons of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colons |
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Term
| What are the endocrine components of the pancreas? |
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Definition
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Term
| What are the exocrine components of the pancreas? |
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Definition
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Term
| What are pancreatic acinar cells? |
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Definition
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