Gastrointestinal Flashcards
What arises from the foregut?
pharynx –> duodenum
What arises from the midgut?
duodenum –> proximal 2/3 of transverse colon
What arises from the hindgut?
disal 1/3 of transverse colon –> anal canal above pectinate line
Duodenal atresia is due to what?
Failure to recanalize (trisomy 21)
Jejunal, ileal, colonic atresia is due to what?
Due to vascular accident (apple peel atresia)
What is gastroischisis?
Extrusion of abdominal contents through abdominal folds; not covered by peritoneum
What is omphalocele?
Persistence of herniation of abdominal contents into umbilical cord, sealed by peritoneum
What is an annular pancreas?
Ventral pancreatic bud abnormally encircles 2nd part of duodenum; forms a ring of pancreatic tissue that may cause duodenal narrowing
What is a pancreas divisum?
Ventral and dorsal parts fail to fuse at 8 weeks
What are the retroperitoneal structures?
“SAD PUCKER:” Suprarenal (adrenal) glands, Aorta and IVC, Duodenum (2nd-4th parts), Pancrease (except tail), Ureters, Colon (descending and ascending), Kidneys, Esophagus, Rectum
What kind of cells line the lumen of the esophagus?
Nonkeratinized stratified squamous epithelium
What kind of cells line the lumen of the stomach?
Gastric glands
What kind of cells line the lumen of the duodenum?
Villi and microvilli, Brunner glands (submucosa), and crypts of Lieberkuhn
What kind of cells line the lumen of the jejunum?
Plicae circulares and crypts of Lieberkuhn
What kind of cells line the lumen of the ileum?
Peyer patches, plicae circulares, and crypts of Lieberkuhn; largest number of goblet cells in small intestine
What kind of cells line the lumen of the colon?
Crypts of Lieberkuhn but no villi; numerous goblet cells
Which zone of the liver contains the portal vein and hepatic artery branches?
Zone I
Which zone of the liver contains the central vein?
Zone III
Which zone of the liver is first affected by viral hepatitis?
Zone I
Which zone of the liver is first affected by alcoholic hepatitis?
Zone III
Which zone of the liver contains cytochrome P450 system?
Zone III
Which zone of the liver is most affected by metabolic toxins?
Zone III
Which zone of the liver is most affected by ingested toxins?
Zone I
Which zone of the liver is first affected ischemia?
Zone III
What does the femoral triangle contain?
Femoral nerve artery and vein
What does the femoral sheath contain?
Femoral vein artery and canal (deep inguinal nodes)
Hesselbach triangle is bordered by what?
Lateral border of rectus abdominus, inguinal ligament, and inferior epigastric vessels
What is the source, action, and regulation of cholecystokinin?
Source: I cells (duodenum and jejunum)
Action: Increase pancreatic secretion and gallbladder contraction, decrease gastric emptying, and increase sphincter of Oddi relaxation
Regulation: Increased by fatty acids and amino acids
What is the source, action, and regulation of gastrin?
Source: G cells (antrum of stomach)
Action: Increases gastric H+ secretion, growth of gastric mucosa, and gastric motility
Regulation: Increased by stomach distention/alkalinization, amino acids, peptides, vagal stimulation. Decreased by stomach pH
What is the source, action, and regulation of glucose-dependent insulinotropic peptide?
Source: K cells (duodenum and jejunum)
Action: Decreases H+ secretion and increases insulin release
Regulation: Increased by fatty acids, amino acids, and oral glucose
What is the source, action, and regulation of motilin?
Source: Small intestine
Action: Produces migrating motor complexes
Regulation: Increased in a fasting state
*erythromycin is a motilin R agonist
What is the source, action, and regulation of secretin?
Source: S cells (duodenmum)
Action: Increased pacreatic bicarb secretion and bile secretion, decreased gastric acid secretion
Regulation: Increased by acid, fatty acids in lumen of duodenum
What is the source, action, and regulation of somatostatin?
Source: D cells (pancreatic islets, GI mucosa)
Action: Decreases gastric acid and pepsinogen secretion, decreases pancreatic and small intestine fluid secretion, gallbladder contraction, and insulin and glucagon release
Regulation: Increased by acid, decreased by vagal stimulation
What is the action of nitric oxide?
Action: Increases smooth muscle relaxation, including lower esophageal sphincter
What is the source, action, and regulation of vasoactive intestinal polypeptide (VIP)?
Source: Parasympathetic ganglia in sphincters, gallbladder, and small intestine
Action: Increase intestinal water and electrolyte secretion, increase relaxation of intestinal smooth muscle and sphincters
Regulation: Increased by distention and vagal stimulation, decreased by adrenergic input
What is the source and action of intrinsic factor?
Source: Parietal cells of stomach
Action: VitaminB12-binding protein - required for absorption of B12 in terminal ileum
What is the source, action, and regulation of gastric acid?
Source: Parietal cells of stomach
Action: Acidify stomach
Regulation: Increased by histamine, ACh, gastrin. Decreased by somatostatin, GIP, PG, and secretin
What is the source, action, and regulation of pepsin?
Source: Chief cells of stomach
Action: Protein digstion
Regulation: Increased by vagal stimulation and local acid
What is the source, action, and regulation of bicarb?
Source: Mucosal cells of stomach, duodenum, salivary glands, and pancreas, and Brunner glands of duodenum
Action: Neutralizes acid
Regulation: Increased by pancreatic and biliary secretion with secretin
Vagal stimulation of the gastric parietal cells works through which receptor?
ACh binds to M3 receptor - Gq
Gastrin stimulation of the gastric parietal cells works through which receptor?
CCKb receptor - Gq
Histamine stimulation of the gastric parietal cells works through which receptor?
H2 receptor - Gs
Prostaglandin stimulation of the gastric parietal cells works through which receptor?
Gi
Somatostatin stimulation of the gastric parietal cells works through which receptor?
Gi
What are Brunner glands?
Located in duodenal submucosa. Secrete alkaline mucus. Hypertrophy seen in peptic ulcer disease.
How is trypsinogen activated to trypsin?
By enterokinase/enteropeptidase, a brush-border enzyme of the duodenal and jejunal mucosa
What is the D-xylose absorption test?
Distinguishes GI mucosal damage from other causes of malabsorption
Bilirubin is conjugated in the liver with what?
Glucuronate
What is sialadenitis?
Inflammation of the salivary gland, due to an obstructing stone usually unilateral s aureus
What is a pleomorphic adenoma?
Benign mixed tumor of the parotid gland
What is a Warthin tumor?
Aka papillary cystadenoma lymphomatosum - benign cystic tumor with germinal centers of parotid gland
What is a mucoepidermoid carcinoma?
Mucin and squamous malignant tumor of parotid gland - can cause facial nerve palsy
What is achalasia?
Failure of relaxation of LES due to loss of myenteric (Auerbach) plexus. High LES opening pressure and uncoordinated peristalsis –> progressive dysphagia to solids and liquids. Increased risk of squamous cell carcinoma.
