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122 Cards in this Set
- Front
- Back
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What is the major function of the esophagus?
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Transport
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What is the major functions of the stomach?
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Mechanical disruption, absorption of water and alcohol
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What are the major functions of the small intestine?
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chemical and mechanical digestion, absorption
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What are the major functions of the large intestine?
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Absorb electrolytes and vitamins, begin generation of feces.
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What are the major functions of the rectum and anus?
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defecation
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What are the 4 major layers of the GI tract from the lumen outwards?
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Mucosa, Submucosa, Muscularis, Serosa (adventitia).
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What two plexuses are associated with the GI tract? Which one is found everywhere in the GI tract?
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The submucosa plexus (plexus of Meissner) is found throughout most of the GI tract. THe Myenteric plexus, (plexus of auerbach) is found everywhere in the GI tract.
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What are the 3 layers of the mucosa from the lumen outwards?
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Epithelium, lamina propria, muscularis mucosae.
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Where are most of the glands and neurons found?
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In the submucosa.
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What tissue type is the submucosa?
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Fibroelastic CT.
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What are the 2 layers of the muscularis layer? Which one is more internal?
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The circular muscle layer is internal to the longitudinal muslce layer.
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What are the two layers of the serosa from most internal to external?
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The connective tissue and the epithelium
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What layer is sometimes continuous with the peritoneom in the GI tract?
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The Epithlium layer of the serosa.
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What type of epithelium is the mucosa in the esophagus and anus? What purpose does this serve?
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Stratified squamous, is protective.
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What type of epithelium is the mucosa in the GI tract in everywhere but the esophagus and anus? What is its purpose?
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Simple Columnar, secretes enzymes and absorbs nutrients.
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What do goblet cells do?
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Secrete mucous onto cell surfaces.
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What do enteroendocrine cells do?
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Secrete hormones.
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Where are Goblet cells and enteroendocrine cells found?
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In the mucosa.
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What is the lamina propria?
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A thin layer of loose CT.
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What is the muscularis mucosae? How many layers is it usually made up of? Where is it made up of a different number?
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A thin layer of smooth muscle. Usually made up of 2 layers. 1 discontinuous layer in the esophagus.
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What type of tissue is the submucosa?
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Loose fibroelastic CT>
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What does the submucosa contain?
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BV, glands, lymphatic tissue, Meissner's plexus.
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Where is the only places the submucosa containes glands?
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esophagus and duodenum.
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Where is skeletal muscle found in the GI tract? What is the purpose of this muscle?
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The skeletal muscle is found in the mouth, pharynx, upper esophagus and anus. It allows for control over swallowing and defecation.
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What two layers make up the smooth muscle of the GI tract? What do they do?
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The inner circular fibers and outer longitudinal fibers. They mix, crush and propel food along by peristalsis.
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What innervates the circular and longitudinal smooth muscle layers?
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Auerbach's plexus (myenteric)
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Embryologically, where all are the neurons and support cells of the gut derived from?
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Neural crest.
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What is the function of the myenteric plexus (auerbach's plexus) and where is it located?
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IT is mostly motor and it regulates peristalsis. It is located between muslce layers in the muscularis externa.
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Is the enteric system part of parasympathetic and sympathetic ganglia?
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NO
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What is the function of the submucosal plexus (Meissner's plexus) Where is it located?
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Mainly secretory-motor, it releases hormones and peptides and innervats the mucosa. IT is located in the submucosa.
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What signalling molecule does the parasympathetic autonomic inputs to the GI tract have and what do they do?
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ACh increasees motility.
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Where does most of the parasympathetic input to the gut come from?
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The vagus nerve.
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What signalling molecule does the sympathetic autonomic inputs to the GI tract have and what do they do?
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NE relaxes the gut.
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What external signal tells myenteric cells to activate?
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Activation of EC cells via a bolus of food deforming the villous surface of the gut.
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Which is more internal the myenteric plexus or the submucosal plexus?
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The myenteric plexus is outside of the submucosal plexus.
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Do the myenteric plexus and submucosal plexus communicate?
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YES
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Together what do the submucosal plexus and the myenteric plexus make up?
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The enteric plexus.
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What is the funciton of the esophagus?
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Move masticated food.
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Describe the epithelium of the esophagus.
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Stratified squamous epithelium.
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Describe the muscularis mucosae of the esophagus.
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Single layer of smooth muscle irregularly distrubuted and discontinuous.
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Describe the lamina propria of the esphagus. What is found in it?
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Dense irregular CT, diffuse lymphoid tissue, arterioles and venules. Also esophageal -cardiac glands, pharynx and gastric junction and sero-mucous glands.
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What type of secretion do esophageal cardiac glands secrete?
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mucous.
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Describe the submucosa of the esophagus. WHat is found in it?
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Dense fibroelastic CT. Also has esophageal glands.
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What do esophageal glands secrete?
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Seromucus, pepsinogen, lysozyme. (beginning of digestion).
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Describe the transition of muscle from upper to lower region of the esophagus.
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Upper region-All skeletal
Middle - skeletal and smooth Lower - All Smooth |
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What is the adventitia or serosa of the esophagus continuous with?
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The adventition of the diaphragm.
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What are the four parts of the stomach?
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Cardia, fundus, body, pylorus
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Which part of the stomach is continuous with the esophagus?
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The cardia.
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What is the main function of the stomach?
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Mechanical and chemical digestion.
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What 4 chemicals does the stomach release? What do each of them do?
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Hydrochloric acid - activates pepsinogen
Pepsin Renin-milk/calcium metabolism Gastric lipase |
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How many layers of smooth muscle does the stomach have? Give them in order from deepest to most superficial.
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Oblique, Circular, longitudinal
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What is the purpose of the oblique muscular layer?
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Adds strength.
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What do the dips in the epithelial lining form?
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Gastric pits.
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What are at the bottom of gastric pits?
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Gastric glands.
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What is found in the submucosa of the stomach?
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Arteries, veins
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What are rugae and where are they found?
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Folds of mucosa and submucosa of the stomach.
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What forms gastric pits?
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Invaginations of the epithelium
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Where are gastric glands found?
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IN the lamina propria and they open into gastric pits.
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Which layer of the muscularis externa forms the pyloric sphincter?
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The middle circular layer.
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What 6 cell types are found in the stomach? Give them in order from most superficial to deepest (going from the lumen in).
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Surface lining cell, regenerative cell, mucous neck cell, parietal cell, chief cell, enteroendocrine cell.
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Describe the action of regenerative cells in the stomach epithelium.
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The migrate up and down and replace all cell types in gland and pit.
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Where are regernation cells found only at the base of the glands?
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Small intestine.
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What are the 3 regions of glands from most superior to inferior (lumen inwards)?
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Isthmus, neck, base.
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What do parietal cells secrete?
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Hydrochloric acid and gastric intrinsic factor.
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What do Chief cells secrete?
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Pepsinogen, gastric lipase, renin.
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What do enteroendocrine cells secrete?
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Glucagon and gastric inhibitory peptide (prevent further HCl production from parietal cells).
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What does HCl do in the gut?
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Converts pepsinogen from chief cell pepsin.
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What is gastric intrinsic factor for? What secretes it?
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Parietal cells secrete it to absorb Vitamin B12.
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What does gastric hormone do?
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Release more gastric juice, increase gastric motility, relax pyloric sphincter, constrict esophageal sphincter.
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What is the primary cell type in the cardiac mucosa of the stomach? What cell do they lack?
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Mostly surface lining cells. NO chief cells.
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What cell types are present in the fundic mucosa?
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All cell types present, regenerative cells replace most of them.
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What type of cells are found in the pyloric mucosa?
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Mainly mucous neck cells, only a few chief cells.
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Destinguich the glands between the cardiac mucosa, fundic and body mucosa, and the pyloric mucosa.
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Cardiac - glands highly coiled, gastric pits shallow
Fundic and body - glands long and straight, gastric pits short Pyloric mucosa - glands branched and deep, gastric pits deep. |
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Which section of the stomach mucosal glands has the shortest isthmus?
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Fundic and body mucosa
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Which section of the stomach mucosal glands has the longest isthmus?
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Pyloric mucosa.
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Describe the changes that Parietal cells undergo to secrete HCl.
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They change structure to secrete.
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What are the 3 ways HCl is produced from parietal cells? What is the signalling molecule associated with each?
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Gastrin (stretch on EC cells)
Histamine (stretch on EC cells) Acetylcholine (vagus nerve, psychological) |
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What is the major stimulus for HCl release in the stomach?
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Stretch of stomach.
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What is the #1 major purpose of the small intestine?
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Absorption.
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Which is longer the duodenum, jejunum, or ilieum?
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The ileum is longest followed by the jejunum and finally the duodenum is only 10 inches long.
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What is the purpose of villi in the small intestine?
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Increase surface area
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Where are regenerative cells found in the small intestine?
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At the base of the crypt of lieberkuhn.
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What cells are found in the small intestine? (5)
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Surface absorptive, goblet cell, enteroendocrine cell, regenerative cell, paneth cell.
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What are plicae circularis? What is their function? What layers do they involve?
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Plicae circularis are large folds of the mucosa and submucosa. Their purpose is to increase surface area.
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Where are villi found inthe small intestine?
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On top of the plicae circularis.
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What lines the villi inthe small intestine?
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Microvilli
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What are the 4 functions of surface absorptive cells in the small intestine?
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Absorb water, reesterify fatty acids, form chylomicrons, trnasport and absorb nutrients.
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Describe the villi of the duodenum. What cells are theier few of? What special gland is found here?
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THe villi are broad, numerous, and tall. They have few goblet cells. They also have Brunner's glands.
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What are Brunner's glands and where are they found? What ist their morphology? What is their purpose?
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Brunner's glands are found in the submucosa of the duodenum. They are tubular alveolar and the secrete an alkaline secretion to neutralize chyme.
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Describe the villi of the jejunum. What cell type is found in large numbers here?
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Their villi are narrow, shorter, and less dense than in the duodenum. They have many goblet cells.
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Describe the villi of the ileum. What special cells are found here? What sort of cells to they have many of?
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The villi are the shortest, narrowest, and smallest in number of the small intestine. They also have peyer's patches and microfold cells. They also have many goblet cells.
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What is the only place peyer's patches are found?
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Ileum.
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What are microfold cells? Where are they found? What do they do?
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Microfold cells are found over the peyer's patch in the ileum. They pick up and transport antigens (M cells).
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What cells are found in the crypts of intestinal glands?
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Stem cells and paneth cells.
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What do crypt cells secrete?
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IgA
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What cell type is diagnostic of the small intestine? Describe them.
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Paneth cells (large, full of granules, secretes lysozyme, at base of gland)
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What do paneth cells do?
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Secrete lysozyme (kills bacteria).
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Where do glands open in the small intestine?
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In between villi.
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Describe enteroendocrine cells.
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Triangle shapped, large nucleus, at the base of gland.
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What type of glands are the crypts of lieberkuhn associated with?
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Simple or branched tubular glands.
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What are the crypts of lieberkuhn comprised of? (5) (cell types)
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Surface absorptive cells, goblet cells, regernative cells, enteroendocrine cells, paneth cells.
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What type of glands are Brunner's glands? Where are they found?
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Branched tubulo alveolar glands (secrete mucous alkaline fluid to neutralize chyme). Brunner's glands are found in the submucosa of the duodenum.
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How long is the large intestine?
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5 ft 2 in
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How long is the rectum?
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8 in
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How long is the anal canal?
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1 in
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What type of muscle and control is involved in the internal sphincter?
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Internal sphincter
Smooth muscle Involuntary control |
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What type of muscle and control is involved in the external sphincter?
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External sphincter
Skeletal muscle Voluntary control |
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What 4 cell types are found in the large intestine?
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Absorptive, goblet, regenerative, enteroendocrine cell
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What special feature does the large intestine have? What does it lack? What type of cells does it have many of?
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Large intestine has crypts of lieberkuhn, no villi or paneth cells. Numerous surface absorptive cells and dense goblet cells.
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Describe the musclular layer of the large intestine.
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Normal circular layer with an unusual longitudinal musculature (Taenia coli).
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What does the visceral peritoneum = in the large intestine?
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Serosa
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What are taenia coli and how many are there?
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They are an outer longitudinal layer that forms three fascicles.
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What do taenia coli form? How do they do this?
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Taenia coli form Haustra coli or sacculations by maintaining constant tonus.
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What are haustra coli?
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Large bumps of the large intestine formed by taenia coli
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How are the crypts in the rectum and anal canal different from the colon? How about goblet cells?
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They are few and deeper crypts. ALso more goblet cells.
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What are the most numerous cells of the rectum and anal canal?
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The surface absorptive cells.
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What happens to the epithelium at the rectal anal junction? what type of glands are found here?
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Epithelium becomes stratifed squamous keratinized. Also branched circumanal glands are found here.
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What is the point at which longitudinal smooth muscle disappears in the anus?
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Puborectalis.
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What happens to the epithelium at the pectineal line?
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Columnar -> PCE
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What forms the internal anal sphincter?
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The circular muscle.
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What plexus is found near the anal canal?
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The external hemprroidal plexus.
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What do the anal columns do?
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The anal columns of margandy provide the strength and flexibility to create and hold a column of feces.
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