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91 Cards in this Set
- Front
- Back
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Fx of Parietal cells
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secrete HCl and intrinsic factor
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Fx of intrinsic factor
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required for absorption of B12 in the ileum
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Location of Parietal cells
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neck of the glands
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Fx of chief cells
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produce pepsinogen and gastric lipase
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Location of Chief cells
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base of the glands
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Pyloric glands
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secrete mucous
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Location of pyloric glands
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near stomach-duodenum junction.
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Morphology of pyloric glands
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long pits, short glands
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Morphology of fundic glands
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straight long glands open into shallow pits
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Location of cardiac glands
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near esophageal/gastric junction
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Fx of cardiac glands
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secrete mucous
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Morphology of cardiac glands
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short gastric pits, short glands
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All gastric glands have
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Mucous neck cells, DNES, and stem cells
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Parts of GI track that are derived from visceral mesoderm
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the muscular walls o the digestive tract and CT (lamina propria, muscularis mucosae, submucosa, muscularis externa, adventitia and/or serosa)
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Parts of the GI tract derived from endoderm
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epithelium of the gut and parenchyma of glands associated with the digestive tract (liver and pancreas)
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Vasculature of foregut
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celiac artery
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Vasculature of midgut
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Superior mesenteric artery
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Vasculature of hindgut
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Inferior mesenteric artery
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Derivatives of primative foregut
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pharynx, respiratory system (lungs and alveoli..), esophagus, stomach, proximal half of duodenum, liver, biliary apparatus and pancreas
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Derivatives of primative midgut
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distal half of duodenum, jejunum, ileum, yolk stalk, cecum and vermiform appendix, ascending colon, proximal 2/3 of transverse colon
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Derivatives of hindgut
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distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, cranial (proximal) 2/3 of anal canal, epithelium or urinary bladder, most of the urethra
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What does the palatoglossal arch represent?
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Oropharyngeal membrane; The junction of the anterior 2/3 and posterior 1/3 of the oral cavity.
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Stomodeum
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yields anterior 2/3 of oral cavity
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Posterior 1/3 of oral cavity derived from
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forgut
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Describe the partitioning of the trachea and esophagus
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Respiratory diverticulum forms on gut tube, tracheoesophageal folds pinch in to form the tracheoesophageal septum. The tubes separate and form the trachea and esophagus
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Esophageal atresia
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results if tracheoesophageal septum is deviated posteriorly. Causes incomplete separation resulting in tracheoesophageal fistula
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Symptoms of esophageal atresia
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maternal polyhydramnios, absence of stomach gas on prenatal US, copious fine white frothy bubbles of mucus in mouth and nose
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Symptoms of tracheoesophageal fistula
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coughing and choking, abdominal distention may occur secondary to collection of air in the stomach
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Esophageal stenosis
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congenital narrowing of the esophageal lumen
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What is the most frequent site of esopheal stenosis
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The distal third of the esophagus
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What causes esophageal stenosis?
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incomplete esophageal recanalization during the 8th week of development
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Pyloric stenosis
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congenital defect in which the opening of the pylorus is too narrow & food is unable to pass into the duodenum. Char: projectile vomitting w/in first 2 wks
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What characteristic does the vomit of a pyloric stenosis pt have?
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No bile in the vomit
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Development of the stomach
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"right back to LA" dorsal swelling rotates 90 degrees clockwise to the right; cranial portion moves inferior, caudal superior
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Hepatic diverticulum
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forms in the ventral mesentary, gives rise to liver and hepatic duct
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Cystic diverticulum
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forms gallbladder and cystic duct
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This becomes the bile duct
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The stalk connecting the hepatic and cystic ducts to the duodenum
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Bare area of liver
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area of liver that articulates with septum transversum (diaphragm) and is not covered by mesentary
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Ventral pancreatic bud
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forms main pancreatic duct, uncinate process and inferior portion of head of the pancreas
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Dorsal pancreatic bud
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forms superior had of pancreas, body and tail of pancreas, accessory bile duct
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Causes duodenums C shape
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The clockwise rotation of the gut tube that brings the two pancreatic buds together
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Duodenum origins
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proximal to bile duct: foregut (celiac artery), distal to bile duct: midgut (superior mesenteric A)
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Duodenal stenosis
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incomplete recanalization of duodenum
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Atresia
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no recanalization
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Symptoms of duodenal stenosis
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recurrent vomitting, gastroesophageal reflux, peptic ulceration
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Symptoms of duodenal atresia
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maternal polyhydramnios, bile containing vomitus, distended stomach
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Physiologic hernia
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due to rapid growth of midgut tube, intestine herniates out into umbilical cord from 6-10wks
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Rotation of midgut
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6th wk: midgut herniates, rotates 90 CC. 10th wk: return to abdominal cavity, rotates 180 CC (total 270 degrees)
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How is the appendix formed?
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during the displacement of the cecum. Originally the cecum is below the right lobe of the liver but then descends into the right iliac fossa
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Nonrotation and malrotation of midgut
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associated with abnormal mesenteric attachment, volvulus and obstruction
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Omphalocoel
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failure of midgut to return to abdominal cavity. Herniated intestines are enclosed in umbilical cord and covered with amnion
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Gastroschisis
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due to abnormal closure of body wall. protrusion of viscera directly into amniotic cavity, occurs lateral to the umbilicus. Viscera not covered by amnion (vs. omphal..)
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Ileal (Meckel's) Diverticulum
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incompletely obliterated vitelline duct (yolk stalk.)
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Cloaca
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terminal end of hindgut
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Partitioning of cloaca
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urogenital sinus and rectum
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Cloacal membrane
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partitioned into urogenital memrane and anal membrane
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Pectinate line
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demarcates junction between upper 2/3 of anal canal (endoderm) and distal 1/3 anal canal (ectoderm)
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White line
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demarcates junction between columnar epithelium and stratified squamous epithelium
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Imperforate anus
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anal membrane fails to break down
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Urorectal fistula
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incomplete partitioning of hindugt
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Hirschsprungs disease
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absence of parasymp ganglia in gut wall due to failure of neural crest cells to migrate to walls of intestines. Peristalsis is absent in affected regions
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Dorsal mesentery
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Greater omentum, mesentery of small intestine, mesoappendix, transverse mesocolon, sigmoid mesocolon
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Ventral mesentery
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Lesser omentum (hepatogastric lig, hepatoduodenal lig) and falciform lig
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Physiologic fx of the fundus of the stomach
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gas trap
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Physiologic fx of the corpus of the stomach
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acid secreting
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Physiologic fx of the antrum of the stomach
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large contractions
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Where in the stomach is acid secreting (oxyntic) mucosa found?
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corpus has parietal cells which secrete acid
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T/F gastric ulcers are most often the result of over secretion of gastric acid
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F; gastric ulcers are most often due to destruction of cytoprotective mechanisms
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Mucus Neck Cell
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Neck of the gastric glands and between parietal cells; secrete mucus
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G-Cell
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Glands in the antrum; secrete gastrin
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Parietal/Oxyntic cell
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Cardia, fundus, and corpus (a lot in corpus!); secrete HCl and intrinsic factor
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Chief cells
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Cardia, fundus, and corpus; secrete pepsinogen (proton activated)
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Surface mucus cells
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Cover the free surface of the glandular stomach and line the upper 1/3 of the gastric pits; secrete mucus and HCO3-
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Stem cells
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gastric glands; replace types 3, 4, and 5
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What are the six components of gastric secretion?
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H+, pepsinogen, mucus, bicarb, intrinsic factor, water
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What is the role of H+ in gastric secretion?
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converts pepsinogen to pepsin, kills bacteria and denatures proteins
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What is the role of pepsinogen in gastric secretion?
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Once converted to pepsin it partly digests protein
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What is the role of mucus in gastric secretion?
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lubricates and protects mucosa
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What is the role of bicarb in gastric secretion
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protects the mucosal surface
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What is the role of intrinsic factor in gastric secretion
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necessary for the normal absorption of vitamin B12
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What is the role of water in gastric secretion
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dissolves and dilutes ingested material
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In a parietal cell, how are bicarb and Cl ion exchanged from the blood?
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Either through passive exchange or a bicarb/Cl exchanger
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In a parietal cell, how are potassium and proton exchanged with the lumen?
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H+/K+ ATPase pump
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In a parietal cell, histaminee works through what second messenger?
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cAMP
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In a parietal cell, acetylcholine and gastrin work through what second messenger?
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DAG and IP3
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The stomach receives sympathetic innervation through
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stellate, celiac, and superior mesenteric ganglia
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The role of histamine in gastric acid secretion
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By working through a different second messenger to land at the same response, histamine potentiates the effects of acetycholine and gastrin
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The effect of prostaglandins, secretin, and somatostatin on gastric acid secretion
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inhibitory
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Prostaglandins
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PGE2 and PGI2 act on EP3 receptors to inhibit the histamine pathway; also stim surface mucus cells to secrete mucus and bicarb
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Secretin
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released from S cells in the duodenal mucosa in response to gastric acid. Opposes gastrins effect on oxynti mucosa. Also promotes bicarb secretion
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Somatostatin
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paracrine agent released from D cells in gastric mucosa. Depresses gastrin release from G cells and opposes effect of gastrin on parietal cells
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