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Histo GI Esophagus and Stomach
Esophagus and Stomach
42
Medical
Graduate
04/11/2011

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Cards

Term
Which epithelial glands have ducts leading to the lumen?
Definition
The submucosal and extramural glands
Term
What layers make up the mucosa of the stomach?
Definition
-Epithelium
-Lamina propria- loose CT
-Muscularis mucosa
Term
Where is there a greater amount of lymphatic tissue, in the upper or lower portions of the GI tract?
Definition
In the lower portion of the GI tract there is a greater amount of lymphatic tissue in the lamina propria and submucosa.
Term
Contrast plicae to rugae?
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.
Term
T/F. Nerves are present in both mucosa and submucosa.
Definition
False. Ganglion cells are present in Meissner's plexus of submucosa but not in the mucosa.
Term
What four structures make up the submucosa?
Definition
-Submucosal glands
-Submucosal folds
-Lymphatics nodules
-Ganglion cells of submucosal (Meissner's) plexus
Term
How are sphincters formed?
Definition
Expansion of the inner circular layer of smooth muscle of the muscularis externa
Term
What two layers make up the muscularis externa?
Definition
Inner circular (IC) and outer longitudinal (OL) smooth muscle layers.
Term
Name and give the location of two sphincters?
Definition
-Pyloric sphincter at the pylorus-duodenal junction
-Internal anal sphincter at the rectal anal junction
Term
Define taenia coli.
Definition
Three longitudinal chords of the large intestine that are formed out of thickened muscularis externa.
Term
What type of nervous tissue is found in the muscularis externa layer?
Definition
Ganglion cells of myenteric (Auerbach's plexus)
Make of the intrinsic nervous system of gut.
Term
Where is auerbach's plexus found?
Definition
Between the inner and outer muscle layers
Term
What does the serosa consist of?
Definition
Loose CT and mesothelium
Term
Define mesothelium.
Definition
Mesothelium is a single layer of squamous epithelial cells covering the GI tract
Term
What two layers is serosa made up of?
Definition
Mesothelium and loose CT on outer layer of GI tracts
Term
What is the difference between serosa and adventitia?
Definition
Adventitia is only loose CT while serosa is loose CT and mesothelium.
Term
What is the composition of muscle of the esophagus as you move down it?
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
Term
T/F. The esophagus has a peritoneal covering.
Definition
False. The outer most layer of the esophagus is adventitia--it lacks a mesothelium
Term
What are the functions of the stomach?
Definition
-secretion of enzymes for digestion of proteins and lipids
-Secrete HCL
-Mashing of food
Term
What type of epithelium makes up the mucosa of the stomach?
Definition
Simple columnar epithelium
Term
T/F. Goblet cells make up the surface cells of the stomach.
Definition
False. Mucous secreting columnar cells are the surface cells of the stomach and also line gastric pits.
Term
What two regions of the stomach are histologically the same?
Definition
The fundis and the body.
Term
Describe gastric pits.
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.
Term
What substances do the surface cells of the epithelia, pits, and glands of the cardiac region of the stomach secrete?
Definition
-Mucous
-lysozyme
-defensins-attack bacterial cell walls
Term
What does pepsin break down?
Definition
Proteins
Term
What does intrinsic factor allow for absorption of?
Definition
Vitamin B12
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?
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?
Definition
Bicarbonate ions passing into the lamina propria via Cl-HCO3
Term
How do bicarbonate ions (HC03-) pass out of the parietal cells?
Definition
In the base of the cell bicarbonate ions pass into the lamina propria via a chloride-bicarbonate antiporter.
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?
Definition
Chloride ions exit via chloride ion channels on the apical membrane into the lumen of the cell
Term
How do the parietal cells go about forming HCl?
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+
Term
Where are chief cells most concentrated?
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
Term
Between parietal and chief cells which stain basophilic? Eosinophilic? Why?
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.
Term
Which cells release hormones that signal the hypothalamus to stimulate appetite?
Definition
Ghrelin containing enteroendocrine cells in the gastric glands.
Term
What substance stimulates parietal cells to release HCl? What cells release this?
Definition
Gastrin stimulates parietal cells to release HCl. G cells release gastrin.
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.
Term
What substances do enterochromaffin (EC) cells release?
Definition
Serotonin and substance P which act on the myenteric and submucosal ganglion cells to increase gut motility.
Term
Which cells are replaced more often surface and pit cells or glandular cells?
Definition
Surface and pit cells
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