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Histology
Digestive II: Esophagus and Gastrointestinal Tract
| Question | Answer |
|---|---|
| The alimentary canal extends from the________ of the esophagus to the __________ of the anal canal. | Proximal portion; distal protion |
| What are the 4 layers of the alimentary canal? | mucosa, submucosa, muscularis, serosa |
| The mucosa layer of the alimentary tract consist of what? | A lining epithelium, underlying connective tissue called the lamina propria, and a layer of smooth muscle called the muscularis mucosa. |
| Most substances that enter the body must first cross what? | digestive mucosa |
| What important antibody does the mucosa of the alimentary canal secrete? | IgA |
| Lymphatic tissue of the alimentary canal is referred to as what? | gut-associated lymphatic tissue (GALT) |
| Peyer's patches are located where? | Distal portion of the small intestine (ileum) |
| The deepest layer of the mucosa of the alimentary canal is the what? | Muscularis layer (serves as a boundary between the mucosa and the submucosa) |
| The submucosa consists of what tissue? | Dense irregular connective tissue |
| The nerve plexus located in the submucosa of the alimentary canal is called the what? | Submucosal (Meissner's plexus) |
| Connective tissue between the 2 layers of the muscularis layers contains what nerve plexus? | Myenteric (Auerbach's plexus) consists of parasympathetic ganglion and postganglionic fibers. |
| The junction between the esophagus and the stomach transitions between what 2 cell types? | stratified squamous epithelium (esophagus) to columnar epithelium (stomach) |
| Cardiac glands of the lower esophagus secrete what? | Neutral mucus |
| What are the histological regions of the stomach? | Cardia (contains cardiac glands), funfus (contains fundic or gastric glands) and pyloric (contains pyloric glands) |
| The apical portion of chief cells contain what? | Zymogen granules |
| Chief cells secrete? | Pepsinogen and a weak lipase |
| Pepsinogen is converted to_______ when _______. | Pepsin; when it comes in contact with gastric juice. |
| Pepsin is a what? | Proteolytic enzyme |
| Parietal cells are found where? | Neck of fundic glands |
| In parietal cells, the membrane of the tubulovesicular system serves as a reservoir for what? | Active proton pumps |
| HCl is produced where in parietal cells? | lumen of the intracellular canaliculi |
| What 3 receptors activate secretion of HCl in parietal cells? | Gastrin, Histamine H2, Acetylcholine M |
| Parietal cells also secrete intrinsic factor. Intrinsic factor does what? | Its a glycoprotein that that forms a complex with Vit. B12; necessary for the vitamin's subsequent absorption in the ileum. |
| The absence of parietal cells causes a condition know as what? | Achlorhydria |
| Achlorhydria causes what? | Pernicious anemia (Vit. B12 deficiency due to the lack of intrinsic factor) |
| Vit. B12 is necessary for what 2 important processes? | RBC production and maintenance of the CNS |
| VIP (vasoactive intestinal peptide) and somatostatin are secreted from ________ to ______. | Fundus to the colon. |
| What are the three sections of the small intestine? | 1. Duodenum, 2. Jejunum, 3. Ileum |
| The main site for digestion and absorption is the what? | Small intestine |
| Enzymes of digestion can be found where? | In the glycocalyx of the microvilli of intestinal absorption cells. |
| Disaccharidases include what 3 enzymes? | sucrase, maltase and lactase |
| Lipid digestion occurs mainly as a result of what? | Pancreatic lipase and bile. |
| Lipid digestion occurs where? | Duodenum and jejunum. |
| Contraction of the terminal web of intestinal microvilli allows for what? | Increased surface area exposure for absorption to take place |
| Tranversely oriented ridges that extend partially around the lumen of the small intestine are called what? | Plicae circulares |
| Plicae circulares are also known as what? | Valves of Kerckring |
| The function of Plicae circulares and intestinal villi is to what? | Increase surface area |
| The surface of intestinal villi are covered by what epithelium? | Simple columnar |
| At the core of the villi, what can be found? | Lacteals (lymphatic vessels) |
| Intestinal glands are also known as what? | Crypts of Lieberkuhn |
| What glands can be found in the submucosa of the duodenum? | Brunner's glands (diagnostic feature of the duodenum) |
| Brunner's gland have what kind of secretions? | Alkaline (help to neutralize acidic chyme) |
| What is the diagnostic feature of the ileum? | Peyer's patches |
| What stain gives a positive reaction for the glycoproteins present in the mucous and the brush border of goblet cells? | PAS-hematoxylin |
| What do Paneth cells do? | They play a role in regulating the normal flora of the small intestine. |
| IgA is secreted what what cells? | Plasma cells (secreted into the lamina propria) |
| IgA does what? | Binds to toxins, antigens and microorganisms in the lumen of the gut. |
| IgA is the ONLY immunoglobin that can do what? | Be selectively passed across the mucosa to the lumen. |
| What is Chrohn's disease? | Chronic inflammatory process that involves the small intestine and can also be observed in the large intestine. |
| The principal functions of the large intestine are what? | Reabsorption of electrolytes and water as well as elimination of undigested food and waste. |
| The 3 distinct longitudinal muscle bands on the outer surface of the large intestine are called what? | Teniae coli muscles |
| Large scculations common to the large intestine are called what? | Haustra (formed by the contractions of the teniae coli muscles) |
| How does appendicitis occur? | When a foreign body is lodged in the lumen of the appendix. |
| The junction between the endodermal and ectodermal derivatives of the large intestine is marked by what? | Pectinate line |
| Hirschsprung's Disease (megacolon) is caused by what? | The lack of neural crest migration to a segment of colon results in aganglionosis, in which Meissner's plexus and Auerbach's plexus do not form. |
Created by:
shuckybean
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