Step 1 - GI 1

denniskwinn's version from 2015-04-25 16:01


Question Answer
Retroperitoneal structuresIVC, Pancreas(except tail), Ascending colon, Rectum, Kidney and ureters, Aorta, Duodenum(2,3,4th parts), Adrenals, Descending colon - I ADD PARKA
Falciform ligamentconnects liver to anterior abdominal wall (contains ligametum teres) - derivative of fetal umbilical vein
Hepatoduodenal ligamentconnects liver to duodenum (contains portal triad: hepatic artery, portal vein, common bile duct) - may be compresses b/w thumb and index finger placed on omental foramen (epiploic foramen of Winslow)- to control bleeding - connects greater and lesser sacs
Gastrohepatic ligamentconnects liver to lesser curvature of stomach (contains gastric arteries) -separates right greater and lesser sacs - may be cut during surgery to access lesser sac
Gastrocolic ligamentconnects greater curvature a nd transverse colon (contains gastroepiploic arteries) - a part of the greater omentum
Gastrosplenic ligamentconnects greater curvature and spleen (contains short gastrics) - separates left greater and lesser sacs
Splennorenal ligamentconnects spleen to posterior abdominal wall (contains splenic artery and vein)
Layers of gut wall (inside to outside)1. Mucosa (epithelium, lamina propria (support), muscularis mucosae (motility) 2. Submucosa (includes meissner’s plexus) 3. Muscularis externa (includes auerbach’s plexus) 4. Serosa/adventitia
Frequency of stomach rhythm3 waves/min
Frequency of duodenum rhythm12 waves/min
Frequency of Ileum rhythm8-9 waves/min
Esophagus histologyNonkeratinized stratified squamous epithelium.
Stomach histology Gastric gland.
Duodenum histologyVilli and microvilli ↑ absorptive surface. Duodenum > jejunum >ileum . - Brunner's glands (submucosa) and crypts of Lieber kuhn .
Jejunum histology has largest number of goblet cell in the small intestine. -Plicae circulares and Crypts of Lieberkuhn .
Ileum histologyPeyer's patches (lamina propria. submucosa), plicae circulares - (proximal ileum), and Crypts or Lieberktihn .
Colon histology has crypts but no villi
Myenteric plexus (auerbach’s)Coordinates Motility along entire gut wall, Contains cell bodies of some parasympathetic terminal effector neurons. . Located between Inner (circular) and outer (longitudinal) layers of smooth muscle in GI tract wall
Submucosal plexus (Meissner’s) Regulates local Secretion, blood flow, and absorption . Contains cell bodies or some parasympathetic terminal effector neurons. - Located between mucosa and inner layer of smooth muscle in GI tract wall.
Esophagus muscleupper 1/3 striated, middle 1/3 striated and smooth, lower 1/3 smooth
Foregut artery/parasympathetic nerve/level/supplyCeliac artery, Vagus nerve, T12/L1 level, Stomach to proximal duodenum, liver, gallbladder, pancreas, spleen (mesoderm)
Midgut artery/parasympathetic nerve/level/supplySMA, Vagus, L1 level , Distal duodenum to proximal 2/3 of transverse colon
Hindgut artery/parasympathetic nerve/level/supplyIMA, Pelvic nerve, L3 level, Distal 1/3 of transverse colon to upper portion of rectum; splenic flexure is a watershed region
Collateral circulationI. Internal thoracic/mammary (subclavian) and superior epigastric (internal thoracic) and inferior epigastric (external iliac) 2. Superior pancreaticoduodenal (celiac trunk) and inferior pancreaticoduodenal (SMA) 3. Middle colic (SMA) and left colic (IMA) 4. Superior rectal (IMA) and middle rectal (internal iliac)
Portal systemic anastamoses1. Left gastric and esophageal (varices) 2. Paraumbilical and superficial and inferior epigastric (caput medusae) 3. Superior rectal and middle and inferior rectal (Internal hemorrhoids)
How to relieve portal hypertensionInserting a portocaval shunt between the splenic and left renal vein or connecting the portal vein to the IVC relives portal hypertension by shunting blood to the systemic circulation
Pectinate lineline where hindgut meets ectoderm at anus
Above pectinate lineInternal hemorrhoids(not painful), adenocarcinoma. Arterial supply from superior rectal artery (branch of IMA). Venous drainage is to superior rectal vein ~ Inferior mesenteric vein → portal system
Below pectinate lineexternal hemorrhoids, squamous cell carcinoma. Arterial supply from inferior rectal artery (branch of internal pudendal artery) Venous drainage to inferior rectal vein → internal pudendal vein → Internal iliac vein → IVC
Femoral region organizationLateral to medial NAVEL
Contents of femoral trianglefemoral vein, artery, nerve
Femoral sheathFascial tube 3-4 cm below inguinal ligament. Contains femoral vein, artery, and canal (deep inguinall lymph nodes) but not femoral nerve.
Diaphragmatic herniaAbdominal structure enter the thorax; may occur in infants a a result of defective development of pleuroperitoneal membrane. Most commonly a hiatal hernia, In which stomach herniates upward through the esophageal hiatus of the diaphragm. - Sliding hiatal hernia most common
Paraesophageal herniaGE junction normal, Cardia moves into thorax
Indirect inguinal herniaGoes through the INternal (deep) inguinal ring, external (superficial) inguinal ring, and into the scrotum. Enters internal inguinal ring lateral to inferior epigastric artery. Occurs in INfants owing to failure of processus vaginalis to close. Much more common in males - follows path of testes descent
Direct inguinal herniaProtrudes through the inguinal (Hesselbach's) triangle. Bulges directly through abdominal wall medial to inferior epigastric artery. Goes through the external (superficial) Inguinal ring only. Covered by external spermatic fascia. Usually in older men.
Femoral herniaProtrudes below inguinal ligament through femoral canal below and lateral to pubic tubercle More Common in women - leading cause of bowel incarceration
MD don’t LIeMedial direct, Lateral indirect (hernias)
Salivary secretion sourcesParotid (most serous), Submandibular and sublingual (most mucinous) glands
Salivary secretion is stimulated byboth Sympathetlc (TI-T3 superior cervical ganglion) and parasympathetic (facial, glossopharyngeal nerve) activity [stimulates]
Saliva tonicityLow flow rate = hypotonic (more time to reabsorb Na+ and Cl-). High rate = closer to isotonic (less time to reabsorb Na+ and Cl-)
Parotid gland surgeryCI VII runs through and can be damaged during surgery
Saliva functions (5)1. Alpha amylase (Ptyalin) begins starch digestions, inactivated by low pH 2. Bicarbonate neutralizes oral bacterial acids - maintains dental health 3. Mucins (glycoproteins) lubricate food 4. Antibacterial secretory products 5. Growth factors that promote epithelial renewal [functions of what?]
Brunner’s glandsSecrete alkaline mucus to neutralize acid contents entering the duodenum from the stomach. located in duodenal submucosa (the only GI submucosal glands) - Hypertrophy of Brunner's glands is seen in peptic ulcer disease
Salivary amylasestarts digestion, hydrolyzes alpha 1,4 linkages to yield disaccharides
Pancreatic amylasehighest concentration in duodenal lumen, hydrolyzes starch to oligosaccharides and disaccharides
Oligosaccharide hydrolasesat brush border of intestine, the rate limiting step in carbohydrate digestion, produce monosaccharides from oligo and di
Carbohydrate absorptionOnly monosaccharides (glucose, ga lactose, fructose) are absorbed by enterocytes. Glucosc and galactose are taken up by SGLT1 (Na+ dependent). Fructose is taken up by facilitated diffusion by GLUT-5. All are transported to blood by GLUT-2
Iron Absorbed as Fe2+ in duodenum.
Folate Absorbed injejunum. [what's absorbed in]
B12 Absorbed in ileum along with bile acids
Peyer’s patchesUnencapsulated lymphoid tissue found in lamina propria and submucosa of small intestine. Contain specialized M cells that take up antigen. B cells stimulated in germinal centers of Peyer's patches differentiate into IgA-secreting plasma cells, which ultimately reside in lamina propria. IgA receives protective secretory component and is then Transported across epithelium to gut to deal with intraluminal antigen.
BileComposed of bile salts (bile acds conjugated to glycine or taurine, making them water soluble), phospholipids, cholesterol, bilirubin, water, and ions. The only significant mechanism for cholesterol excretion. Needed for digestion of triglycerides and micelle formation in small intestine
Bilirubinproduct of heme metabolism, removed from blood by liver, conjugated with glucoronate and excreted in bile.
Direct bilirubinconjugated with glucoronic acid, water soluble
Indirect bilirubinunconjugated; water insoluble
Salivary gland tumorsGenerally benign and occur in parotid gland. Types: pleomorphic adenoma, (most common tumor; painless, movable mass; benign with high rate of recurrence), Warthin 's tumor (benign; heterotopic salivary gland tissue trapped in a lymph node, surrounded by lymphatic tissue), and mucoepidermoid carcinoma (most common malignant tumor).
Achalasiadue to loss of AUERBACH’s plexus - high LES opening pressure, uncoordinated peristalsis→progressive dysphagia . Barium swallos shows bird beak - ↑ risk of esophageal carcinoma . . Secondary achalasia in Chaga’s
CREST associated with esophagealdysmotility
GERDCommonly presents as heartburn and regurgitation upon lying down - may present With nocturnal cough and dyspnea.
Esophageal varicesSign of portal hypertension; Painless bleeding of submucosal veins In lower 1/3 of esophagus
Mallory -weiss syndromePainful mucosal lacerations at the gastroesophageal junction due to severe vomiting - leads to hematemesis. Usually found in alcoholic and bulimics.
Boerhaave syndromeTransmural esophageal rupture due to violent retching. "BeenHeeving syndrome”
Esophageal strictures Associated With lye ingestion and acid reflux
Esophagitis associated withreflux, infection (HSV1, CMV, Candida) or chemical ingestion
Plummer vinson syndromeTriad of: 1. DysphagIa (due to esophageal webs) 2.Glossitis 3. Iron deficiency anemia
Barrett’s esophagusGlandular metaplasia - replacement of nonkeratinized (stratified) squamous epithelium with intestinal (columnar) epithelium in the distal esophagus to chronic reflux
Esophageal cancer risk factors1. Alcohol/Achalasia, 2.Barett’s esophagus, 3.Cigarettes, 4.Diverticuli, 5.Esophageal web,6. Esophagitis
Squamous cell Ca risks:1,3,5; Adrenoca: 2,4,6
Malabsorption syndromes can causediarrhea, steatorrhea, weight loss
Celiac sprue (1. pathophys; 2. area it affects; 3. people it affects; 4. dx; 5. histo; 6. a/w?)1.AutoantibodIes to gluten (gliadin ) in wheat and other grains. 2.Proximal small bowel primarily. 3. Associated with people of northern european descent - 4.finding of antibodies to gliadin and tissue transglutaminase, 5. blunting of villi, lymphocytes in lamina propria - primarily jejunum, 6. Associated with dermatitis herpetiformis
Tropical sprueProbably infectious; responds to antibiotics. Similar to celiac sprue, but can affect entire small bowel.
Whipple’s diseaseInfection with Trophyerma whippelii (gram+), PAS+ MACROPHAGES in intestinal lamina propria (in comparison to celiac dx which has lymphocytes), mesenteric nodes. Arthralgia, cardiac and neurologic symptoms are common. Most often occurs in older men.
Disaccharidase deficiencyMost common is lactase deficiency→ milk intolerance. Normal-appearing villi, Osmotic diarrhea . Since lactase is located at tips of intestinal villi, seif-limited lactase deliciency can occur following injury (e .g., viral diarrhea)
Pancreatic insufficiencyDue to cystic fibrosis, obstructing cancer, and chronic pancreatitis. Causes malabsorption of fat and fat-soluble Vitamins
Abeta-lipoproteinemia↓synthesis of apo B → inability to generate chylomicrons→ ↓ secretion of cholesterol, VLDL into bloodstream → fat accumulation In enterocytes. Presents in early childhood with malabsorption and neurologic manIfestations (MR, DD)
Acute gastritis (erosive )Disruption of mucosal barrier → inflammation. Especially common in alcoholics and those taking daily NSAIDS (RA) . . Can be caused by stress, NSAIDs (↓ PGE2 → ↓ gastric mucosa protection), alcohol, uremia, burns (Curling's ulcer = ↓ plasma volume→ sloughing of gastric mucosa) and brain injury (Cushing’s ulcer - increased vagal stimulation )
.Type A chronic gastritisAutoimmune disorder: Autoantibodies to parietal cells, pernicious anemia, Achlorhydria, associate with other autoimmune disorders - in fundus and body
Type B chronic gastritisMost common type caused by H. Pylori infection - ↑ risk of MALT lymphoma -
Menetrier’s diseaseGastric hypertrophy with protein loss, parietal cell atrophy, and ↑ mucous cells. Precancerous. Rugae of stomach are so hypertrophied that they look like brain gyri
Stomach cancerAlmost always adenocarcinoma. Early aggressive local spread and node/livcr mets. ASSOCiated with dietary nitrosamines (smoked foods), achlorhydria, chronic gasritis, Type A blood. Signet ring cells, acanthosis nigricans(dark, thick, velvety skin in body folds and creases.) are common features. *metastasizes to supraclavicular node (Virchow's tumor); ovary (Krukenburg tumor); and Umbilicus (Sister Mary Joseph tumor)
Linitis plasticastomach cancer when diffusely infiltrative (thickened rigid appearance
Virchow’s nodeinvolvement of left supraclavicular node by mets from stomach
Krukenberg’s tumorbilateral stomach cancer mets to ovaries, abundant mucus, signet ring cells
Sister mary joseph nodulesubcutaneous periumbilical metastasis of stomach cancer
Gastric ulcerPain can be Greater with meals-weight loss. Often occurs in older patients. H.pylori Infection in 70%; chronic NSAID use also implicated. - Due to ↓ mucosal protection against gastric acid .
Duodenal ulcerPain Decreases with meals-weight gain. Almo s 100% have H. pylori. - Due to ↑ gastric acid secretion (e.g., Zollinger-Ell icon syndrome-caused by gastrinomas) or ↓ mucosal protection. Hypertrophy of Brunner's glands.
Peptic ulcersTend to have clean, "punched-out" margins unlike the raised/irregular margins of carcinoma. Potential complications include bleeding, penetration into pancreas, perforation, and obstruction (not intrinsically precancerous).
IBSRecurrent abdominal pain associated with 2+ of the following: 1.Pain Improves with defecation 2. Change in stool frequency 3. Change in appearance of stool. . . No structural abnormalities. may present with diarrhea, constipation, or alternating. Pathophysiology is multifaceted. . . Treat symptoms.



Question Answer
Celiac trunk levelT12 [level of]
SMA levelL1 [level of]
Left renal artery levelL1 [level of]
Testicular or ovarian arteries levelL2 [level of]
IMA levelL3 [level of]
Bifurcation of abdm aorta levelL4 [level of]