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RUSOM_GI Histo I

Esophagus to Anus

QuestionAnswer
What are the 4 layers of the digestive tract, from superficial to deep? 1. Mucosa 2. Submucosa 3. Muscularis externa 4. Serosa or adventitia
What type of epithelium is normally found in the mucosa layer? Non-keratinized stratified squamous epithelium
What is GALT? Gut-Associated Lymphatic Tissue: Immune system tissue found in digestrive tract
Which layers is GALT found in? Mucosa & Submucosa
What is the function of muscularis mucosae? Localized movement of the mucosa
Which part of the digestive tract does NOT have muscularis mucosae? Gallbladder
What is the function of muscularis externa? Peristalsis: constricts & shortens the GI tube to propel food towards the caudal end of the GI tract
Where is Meissner's plexus located? Submucosa
Where is Myenteric plexus located? Muscularis externa
What type of ganglia are found in Meissner's plexus? Parasympathetic
What type of ganglia are found in Myenteric plexus? Parasympathetic
Do intraperotineal organs have a serosa or an adventitia layer? Serosa
Do retroperotineal organs have a serosa or an adventitia layer? Adventitia
Is mesothelium found in serosa or in adventitia? Serosa
What is the embryological derivative of mesothelium? Mesoderm
Which condition presents with a cardiac gland in the lamina propria of the cardia region of the stomach? Chronic acid reflux
What shape lumen is found in the esophagus? Stellate-shaped lumen
Where is the physiological sphincter of the stomach? Cardia
Where is the anatomical sphincter of the stomach? Pylorus
What are the 2 layers of muscularis externa? Inner circular & outer longitudinal
What is found in the lamina propria of the mucosa layer? GALT
Which condition is related to a lack of protection for the esophageal mucosa from esophageal mucus? GERD (Gastro-Esophageal-Reflux-Disease)
Which condition is found in patients who allow GERD to persist for too long? Barrett's esophagus
Which types of epithelia are affected in Barrett's esophagus? Gastric & intestinal epithelia
What type of metaplasia occurs in patients with Barrett's esophagus? Stratified squamous epithelium is replaced by simple columnar epithelium
What does congenital metaplasia in the esophagus indicate? The metaplasia is not precancerous (ie, found in babies)
What does acquired metaplasia in the esophagus indicate? The metaplasia is precancerous
What could result from chronic heartburn? Barrett's esophagus --- then esophageal cancer
What pH is found in the stomach? 1-2
What types of digestion occur in the stomach? Chemical & physical digestion
What is the function of pepsin? Breaks down dietary proteins into peptides
What condition would occur if self-digestion of the stomach is not prevented? Gastric ulcers
Which region of the stomach has a dome shape? Fundus
What happens to the rugae when the stomach is full? The rugae 'disappear' or flatten out as the stomach fills.
What are gastric pits? Invaginations of mucosa that terminate as gastric glands
What type of epithelium is found in mucosal pits and glands? Simple columnar
What is the function of the mucosa in the stomach? To produce a thick mucus layer to protect the stomach from self-digestion
What does PAS stain + for? Sugar residues, such as mucin (a glycoprotein) in mucus
What color is a PAS+ cell? Magenta
What is the major type of gland in the cardia? EEC (Enteroendocrine cells)
Where are parietal cells found? (Be specific.) Fundus of stomach - neck of deep glands
What is the function of parietal cells? Produce HCl & Intrinsic factor
Where are chief cells found? (Be specific.) Fundus of stomach - base of deep glands
What is the function of chief cells? Produce pepsinogen & weak lipase
Where are stem cells found in the fundus? (Be specific.) Neck of deep glands
Are parietal cells acidophilic or basophilic? Why? Acidophilic - they have a lot of mitochondria for active transport
Are chief cells acidophilic or basophilic? Why? Basophilic - they have a lot of Rough ER
What is another name for parietal cells? Oxyntic cells
What is the function of intrinsic factor? It binds to Vitamin B12 so that it can be taken up in the ileum.
What condition results from gastric atrophy? Why? Pernicious anemia - A patient will not produce intrinsic factor, so they will not bind Vitamin B12, which leads to a Vitamin B12 deficiency.
What cell types are found in the cardia? Mucus-secreting cells & EEC
What cell types are found in the fundus/body? Mucus-neck cell, PARIETAL cells, CHIEF cells, EEC
What cell types are found in the pylorus? Mucus-secreting cell, EEC
What is another name for chief cells? Zymogenic cells or Peptic cells
What do G cells produce? Gastrin
What does gastrin stimulate? HCl production in parietal cells
What do D cells produce? Somatostatin
What does somatostatin stimulate? Decrease in gastrin production
What does HCl stimulate? Somatostatin production in D cells
What is the protective mechanism of the stomach? 1. Mucus 2. Bicarbonate 3. Prostaglandins
What is the function of prostaglandins in the stomach? They inhibit gastric HCl production by inhibiting parietal cells
How long does it take to regenerate surface cells in the stomach? 3-7 days
What can cause an acute insult to the stomach? Alcohol, aspirin, toxins, chemotherapy drugs, radiation treatments
What happens to the stomach as a result of an acute insult? Surface mucus cells are damaged, stem cells in pits & glands migrate up and cover the surface
What condition results from a failure of protective mechanisms in the stomach following an acute insult? Ulcers and bleeding
What is the pH range in normal pits & glands in the stomach? Surface layer = pH 1-2; bottom of pit/gland = pH 7
What is unique about the muscularis externa in the stomach? There are 3 layers: 1. Inner oblique 2. Middle circular 3. Outer longitudinal
Does the stomach have serosa or adventitia? Serosa (it's an intraperotineal organ)
What are the 3 regions of the small intestine, in order? Duodenum, Jejunum, Ileum (DJ Ileum)
What are the characteristic features of the small intestine? Villi, crypts in the mucosa Transverse folds (plicae circulares)
What 5 cell types are found in the epithelium of the small intestine? 1. Enterocytes/absorptive cells 2. Goblet cells 3. EEC (APUD cells) 4. Paneth's cells 5. Stem cells
What are the characteristics of the Enterocytes in the Small intestine? Brush border of microvilli, glycocalyx coating, decreased frequency towards large intestine
What is the function of Goblet cells? Secret mucus, increased frequency towards large intestine
What immune protections are found in the small intestine? sIgA tight junctions between enterocytes GALT
What cells can a stem cell in the small intestine produce? enterocytes EEC Goblet cells Paneth's cells
What is the function of EEC/ APUD cells in the small intestine? Hormone production (gastrin, secretin, CCK, somatostatin); hormones are released locally and modulate GI activities
Where are EEC/ APUD cells found? In crypts of the small intestine
What is the function of Paneth's cells in teh small intestine? Produce lysozyme (antimicrobial; kills bacteria by breaking down cell walls)
Where are Paneth's cells found? At the base of crypts in small intestine
What is the function of gastrin? Stimulates parietal cells (HCl) and chief cells (pepsin)
What is the function of somatostatin? Inhibits parietal cells (HCl) and chief cells (pepsin)
What is the function of serotonin? Stimulate smooth muscle contraction (EC cells in small intestine, fundus of stomach)
What it the function of CCK (cholecystokinin)? Stimulate bile production & pancreatic enzyme secretion
What is the function of secretin? Stimulate pancreatic & biliary bicarbonate and water secretion
How do Paneth cell granules look? Black protein core surrounded by clear/white halo
What are the characteristics of a closed-type EEC? Granules are everywhere in cell; hormones are released from the bottom into circulation
What is the function of a lactael? It is a lymph vessel that absorbs chylomicrons
Where are Brunner's glands located? Duodenum
Where are Peyer's patches located? Ileum
Which portion of the small intestine does not contain Brunner's glands or Peyer's patches? Jejunum
What is produced by Brunner's glands? Alkaline mucin pH 8.2-9.3
Where does alkaline mucin empty into? Neck of crypts in duodenum
What is the function of alkaline mucin? Protects against acid chyme; creates optimal pH for pancreatic enzymes
What is the function of Peyer's patches? Part of GALT system; covered by M (microfold cells)--- important for immune response
Are M cells APC (antigen-presenting cells)? No.
Does small intestine have serosa or adventitia? Both. Serosa where small intestine lies free in abdominal cavity; Adventitia where small intestine is attached to the body wall
What is the shape of Brunner's gland? Leaf-like villi
What is the shape of Peyer's patches? Finger-like villi
Which digestive enzymes are secreted by the pancreas into the small intestine? Amylase, lipase, peptidase, trypsin
What cleaves trypsinogen to trypsin? Enterokinase from enterocytes
What are the functions of trypsin? Cleaves pancreatic enzymes into active form; Breaks polypeptides
Where is bile reabsorbed? In the small intestine
What are the protective mechanisms of the small intestine? 1. Glycocalyx 2. Goblet cells 3. Brunner's glands 4. Bile 5. Pancreatic fluid
What type of secretions are released into the small intestine, and why? Alkaline; to neutralize stomach acid
Where are ulcers more common; in the stomach or in the duodenum? Duodenum (8%) > Stomach (2%)
What is usually found in patients with GI ulcers? + for H. pylori bacteria
What are the basic functions of the Large intestine? Reabsorption of water & salts from feces; propel feces out of body
Does digestion occur in the Large intestine? No.
What is the role of Flora & Fauna in the Large intestine? Extraction of vitamins
Which part(s) of the Large intestine have serosa? Trans-colon (Intraperotineal)
Which part(s) of the Large intestine have adventitia? Ascending colon, Descending colon (Retroperotineal)
What cell types are found in Large intestine epithelia? Columnar absorptive, Goblet cells (***), EEC, Stem cells
What is special about the muscularis externa of Large intestine? Outer longitudinal layer has 3 longitudinal stripes -- taeniae coli
What are the characteristics of the appendix? Same histology as Large intestine, filled entirely with diffuse lymphatic tissue and nodules, contains plasma cells
What could result from a burst appendix? Infection could spread into abdomen (peritoneal cavity)
What leads to infection of the appendix? Small lumen becomes obstructed, invaded by bacteria
How does the rectum differ from the colon? It lacks taeniae coli
What causes Congenital megacolon (Hirschsprung's disease)? Absence of parasympathetic ganglia in bowel wall
What is the embryological origin of parasympathetic ganglia in the bowel wall? NCC
What signs/symptoms are present in a patient with Congenital megacolon (Hirschsprung's disease)? Aganglionic sone permanently contracted (no relaxation from parasympathetic system), proximal bowel becomes dilated, bowel obstruction starts at anus and progresses upwards
What are the Columns of Morgagni (Anal columns)? Vertical folds produced by infolding of mucus membrane & muscular tissue in the upper hald of the lumen of the anal canal
What artery supplies the upper 1/2 of the anal columns? Superior rectal a. (branches of IMA)
What artery supplies the lower 1/2 of the anal columns? Inferior rectal a. (branches of internal Pudendal a.)
What separates the anal canal into upper and lower parts? Pectinate line
Why is the pectinate line an important landmark? Above the pectinate line -- sup. rectal a. & v., columnar epithelium, ENDODERM Below the pectinate line -- inf. rectal a. & v., stratified squamous epithelium, ECTODERM
Where are hemorrhoids found within the anal canal? Surrounding the pectinate line; plexus of large veins in lamina propria
What type of muscle is found in the internal anal sphincter? Thickened inner circular layer of muscularis externa
What type of muscle is found in the external anal sphincter? Skeletal muscle
Created by: 1683642184