Term
| Which epithelial glands have ducts leading to the lumen? |
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Definition
| The submucosal and extramural glands |
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Term
| What layers make up the mucosa of the stomach? |
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Definition
-Epithelium
-Lamina propria- loose CT
-Muscularis mucosa |
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Term
| Where is there a greater amount of lymphatic tissue, in the upper or lower portions of the GI tract? |
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Definition
| In the lower portion of the GI tract there is a greater amount of lymphatic tissue in the lamina propria and submucosa. |
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Term
| Contrast plicae to rugae? |
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Definition
| Plicae are located in the small intestine and are permanent folds that expand surface area for digestion. Rugae are temporary folds in the stomach that allow for increases stomach volume. |
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Term
| T/F. Nerves are present in both mucosa and submucosa. |
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Definition
| False. Ganglion cells are present in Meissner's plexus of submucosa but not in the mucosa. |
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Term
| What four structures make up the submucosa? |
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Definition
-Submucosal glands
-Submucosal folds
-Lymphatics nodules
-Ganglion cells of submucosal (Meissner's) plexus |
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Term
| How are sphincters formed? |
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Definition
| Expansion of the inner circular layer of smooth muscle of the muscularis externa |
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Term
| What two layers make up the muscularis externa? |
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Definition
| Inner circular (IC) and outer longitudinal (OL) smooth muscle layers. |
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Term
| Name and give the location of two sphincters? |
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Definition
-Pyloric sphincter at the pylorus-duodenal junction
-Internal anal sphincter at the rectal anal junction |
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Term
|
Definition
| Three longitudinal chords of the large intestine that are formed out of thickened muscularis externa. |
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Term
| What type of nervous tissue is found in the muscularis externa layer? |
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Definition
Ganglion cells of myenteric (Auerbach's plexus)
Make of the intrinsic nervous system of gut. |
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Term
| Where is auerbach's plexus found? |
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Definition
| Between the inner and outer muscle layers |
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|
Term
| What does the serosa consist of? |
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Definition
|
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Term
|
Definition
| Mesothelium is a single layer of squamous epithelial cells covering the GI tract |
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Term
| What two layers is serosa made up of? |
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Definition
| Mesothelium and loose CT on outer layer of GI tracts |
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Term
| What is the difference between serosa and adventitia? |
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Definition
| Adventitia is only loose CT while serosa is loose CT and mesothelium. |
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Term
| What is the composition of muscle of the esophagus as you move down it? |
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Definition
At the tops of the esophagus is only skeletal muscle
The next third contains both skeletal muscle and smooth muscle
The bottom third of the esophagus contains only smooth muscle |
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Term
| T/F. The esophagus has a peritoneal covering. |
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Definition
| False. The outer most layer of the esophagus is adventitia--it lacks a mesothelium |
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Term
| What are the functions of the stomach? |
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Definition
-secretion of enzymes for digestion of proteins and lipids
-Secrete HCL
-Mashing of food |
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|
Term
| What type of epithelium makes up the mucosa of the stomach? |
|
Definition
| Simple columnar epithelium |
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Term
| T/F. Goblet cells make up the surface cells of the stomach. |
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Definition
| False. Mucous secreting columnar cells are the surface cells of the stomach and also line gastric pits. |
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Term
| What two regions of the stomach are histologically the same? |
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Definition
|
|
Term
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Definition
| Gastric pits are invaginations of the stomach epithelium into the the lamina propria. Lined with mucous secreting columnar cells. Branched tubular gastic glands open into the bottom of gastric pits. |
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Term
| What substances do the surface cells of the epithelia, pits, and glands of the cardiac region of the stomach secrete? |
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Definition
-Mucous
-lysozyme
-defensins-attack bacterial cell walls |
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Term
| What does pepsin break down? |
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Definition
|
|
Term
| What does intrinsic factor allow for absorption of? |
|
Definition
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Term
What do parietal cells secrete?
Where are they found? |
|
Definition
-HCl
-Intrinsic factor
Found
-few in glands of cardia of stomach
-throughout glands of fundic region though concentrated at apical portion |
|
|
Term
| What tissue layers do the pits and glands of the stomach pass through? |
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Definition
Gastric pits (foveolae) are invaginations only into the lamina propria
Branched tubular gastric glands are located in the lamina propria with the bottom of the gland lying above the muscularis mucosa. |
|
|
Term
| What substances do parietal cells secrete? |
|
Definition
HCl-for digestion and converts pepsinogen to active pepsin
Intrinsic factor-absorption of B12 |
|
|
Term
| In parietal cells, what allows for local protections from protons that diffuse into the intercellular space? |
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Definition
| Bicarbonate ions passing into the lamina propria via Cl-HCO3 |
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Term
| How do bicarbonate ions (HC03-) pass out of the parietal cells? |
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Definition
| In the base of the cell bicarbonate ions pass into the lamina propria via a chloride-bicarbonate antiporter. |
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Term
| If chloride ions are pumped into the parietal cell via a chloride ion antiporter in the base of the cell how is it that chloride does not build up in the cell? |
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Definition
| Chloride ions exit via chloride ion channels on the apical membrane into the lumen of the cell |
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|
Term
| How do the parietal cells go about forming HCl? |
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Definition
| Parietal cells secrete HCl by pumping in chloride from the basal membrane through the Cl-HCO3 antiporter. The chloride then passes through chloride ions. A proton is formed when carbonic anhydrase breaks down carbonic acid. ATPase proton pumps then actively pump protons into the lumen in exchange for K+ |
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Term
| Where are chief cells most concentrated? |
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Definition
| In the basal portion of fundic glands. |
|
|
Term
| What substances do chief cells secrete? |
|
Definition
-Digestive enzymes called zymogen
-pepsinogen which becomes pepsin
-lipase which splits fats |
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Term
| Between parietal and chief cells which stain basophilic? Eosinophilic? Why? |
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Definition
| Chief cells stain basophilic due to the large amount of RER typical of protein secreting cells. The cytoplasm of parietal cells stains eosinophilic, while the nucleus stains basophilic. |
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Term
| Which cells release hormones that signal the hypothalamus to stimulate appetite? |
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Definition
| Ghrelin containing enteroendocrine cells in the gastric glands. |
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Term
| What substance stimulates parietal cells to release HCl? What cells release this? |
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Definition
| Gastrin stimulates parietal cells to release HCl. G cells release gastrin. |
|
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Term
| Where are G cells located? |
|
Definition
| Found in the glands of pyloric antrum and duodenum. |
|
|
Term
| What function does somatostatin have? What cells release somatostatin? |
|
Definition
| Somatostatin inhibits the release of hormones from other entroendocrine cells nearby through paracrine secretion. D cells release somatostatin. |
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Term
| What substances do enterochromaffin (EC) cells release? |
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Definition
| Serotonin and substance P which act on the myenteric and submucosal ganglion cells to increase gut motility. |
|
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Term
| Which cells are replaced more often surface and pit cells or glandular cells? |
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Definition
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