Gastroenterology – Digestive Tract Essentials

Vocabulary flashcards cover fundamental structures, functions, cells, hormones, disorders, and procedures discussed in the gastroenterology lecture to aid comprehensive exam review.

Gastroenterology

Medical specialty focused on diagnosing and treating disorders of the digestive tract, liver, gallbladder, and pancreas.

Gastroenterologist

Physician who cares for patients with acute and chronic digestive tract issues and performs procedures such as colonoscopies and endoscopies.

Gastrointestinal (GI) Tract

Continuous 30-foot tube from mouth to anus, including accessory organs (pancreas, gallbladder, liver) that functions in digestion, absorption, and waste excretion.

Mucosa

Innermost GI layer that lines the lumen, secretes mucus, and absorbs nutrients.

Submucosa

GI layer containing blood vessels, nerves, and lymphatics that support the mucosa.

Muscularis Propria (Muscularis Externa)

Two smooth-muscle layers in the GI tract responsible for peristalsis.

Serosa

Outer GI covering that anchors organs; absent in retroperitoneal structures where it is called adventitia.

Peristalsis

Wave-like contractions that propel food through the digestive tract.

Bolus

Mass of chewed food propelled from mouth to stomach during swallowing.

Esophagus

Muscular tube connecting pharynx to stomach and moving food via peristalsis.

Upper Esophageal Sphincter (UES)

Skeletal-muscle valve that opens during swallowing and prevents air entry into the stomach.

Lower Esophageal Sphincter (LES)

Smooth-muscle valve that prevents gastric reflux into the esophagus.

Stomach

Organ that performs mechanical digestion and acid breakdown of food into chyme.

Parietal Cell

Stomach cell that secretes hydrochloric acid and intrinsic factor for vitamin B₁₂ absorption.

Chief Cell

Stomach cell that secretes pepsinogen, the precursor to the protein-digesting enzyme pepsin.

G Cell

Stomach endocrine cell that secretes gastrin to stimulate acid production.

Chyme

Semi-liquid mixture of partially digested food produced in the stomach.

Rugae

Folds in stomach submucosa that allow expansion after eating.

Small Intestine

Duodenum, jejunum, and ileum; primary site for nutrient and water absorption.

Duodenum

First part of the small intestine that receives bile and pancreatic enzymes; contains Brunner’s glands to neutralize stomach acid.

Cholecystokinin (CCK)

Hormone from small intestine that stimulates gallbladder contraction, pancreatic enzyme release, and regulates satiety.

Jejunum

Middle section of small intestine where most nutrient absorption (carbs, proteins, vitamins, water) occurs.

Ileum

Distal small intestine segment that absorbs vitamin B₁₂, bile salts, and connects to colon via the ileocecal valve.

Villi

Finger-like projections of small-intestinal mucosa that increase surface area for absorption.

Microvilli (Brush Border)

Microscopic membrane extensions on intestinal epithelial cells that further amplify absorptive surface.

Large Intestine (Colon)

Segment that absorbs remaining water and electrolytes and forms feces.

Teniae Coli

Three longitudinal muscle bands in the colon that create haustra via contractions.

Haustra

Sac-like pouches of the colon formed by teniae coli contractions.

Appendix

Narrow pouch off the cecum with proposed immune function.

Water Absorption (GI)

Process by which 85-90% of water is absorbed in the small intestine and 10-15% in the large intestine via osmosis and active sodium transport.

Pancreas – Exocrine Function

Acinar cells secrete inactive digestive enzymes (zymogens) into ducts that empty into duodenum.

Pancreas – Endocrine Function

Islet cells secrete hormones: α-glucagon, β-insulin & amylin, δ-somatostatin, ε-ghrelin, PP-pancreatic polypeptide.

Gallbladder

Organ that stores and concentrates bile; stimulated by CCK to release bile for fat emulsification.

Liver

Organ with dual blood supply (portal vein & hepatic artery) responsible for metabolism, detoxification, and synthesis (e.g., clotting factors).

GERD (Gastroesophageal Reflux Disease)

Condition of recurrent acid reflux due to LES relaxation causing heartburn; complications include Barrett esophagus and cancer.

Peptic Ulcer Disease

Mucosal sores (mainly duodenum) often linked to H. pylori or NSAIDs; treated with proton pump inhibitors.

Zollinger-Ellison Syndrome

Excess gastric acid from gastrin-secreting tumor (gastrinoma) leading to hypertrophic parietal cells and refractory ulcers.

Inflammatory Bowel Disease (IBD)

Autoimmune disorders Crohn’s disease and ulcerative colitis characterized by chronic intestinal inflammation and cancer risk.

Crohn’s Disease

IBD with transmural inflammation, skip lesions, and granulomas that can affect any GI segment mouth to anus.

Ulcerative Colitis

IBD limited to colon and rectum with mucosal inflammation producing continuous ‘lead-pipe’ appearance.

Celiac Disease

Immune reaction to gluten (gliadin) causing villous atrophy; diagnosed with anti-tTG antibodies and biopsy.

Colon (Colorectal) Cancer

Second leading cause of cancer death; usually adenocarcinoma; screening begins at age 45.

Pancreatitis

Inflammation of pancreas commonly from gallstones or alcohol; diagnosed by lipase >3× ULN and treated with fluids and early feeding.

Pancreatic Cancer

Fourth leading cause of cancer death with poor 5-year survival; risk factors include chronic pancreatitis and smoking.

Gallstones (Cholelithiasis)

Cholesterol stones in gallbladder; risk factors: female sex, estrogen, obesity, age; can cause cholecystitis or pancreatitis.

Cholecystitis

Inflammation/ischemia of the gallbladder usually from obstructing gallstone.

Choledocholithiasis

Presence of gallstones in the common bile duct, potentially leading to cholangitis or pancreatitis.

Cholangitis

Infection of the bile ducts often due to obstruction by stones (choledocholithiasis).

Biliary Pancreatitis

Pancreatitis triggered by gallstones obstructing the pancreatic duct or ampulla.

Cirrhosis

Irreversible liver scarring from chronic injury (alcohol, hepatitis, obesity) leading to portal hypertension and organ failure.

MELD Score

Model for End-Stage Liver Disease; score >15 prompts consideration for liver transplantation.

Upper Endoscopy (EGD)

Flexible scope procedure to visualize and treat disorders of esophagus, stomach, and duodenum.

Colonoscopy

Endoscopic examination of the colon used for screening, polyp removal, and biopsy.

ERCP (Endoscopic Retrograde Cholangiopancreatography)

Endoscopic technique to diagnose and treat bile or pancreatic duct disorders.

Endoscopic Ultrasound (EUS)

Combines endoscopy and ultrasound to create detailed images of GI tract and nearby organs.

Feeding Tube (Enteral Nutrition)

Tube delivering nutrition to GI tract when oral intake is inadequate; routes include nasogastric or jejunal.

Proton Pump Inhibitor (PPI)

Drug class that blocks parietal cell H⁺/K⁺ ATPase, lowering stomach acid to treat GERD and ulcers.

Peristaltic Swallowing Phases

Voluntary oral phase, autonomic pharyngeal phase (soft palate & epiglottis closure), and involuntary esophageal phase.

Intrinsic Factor

Glycoprotein from parietal cells essential for vitamin B₁₂ absorption in the ileum.

Brunner’s Glands

Duodenal submucosal glands that secrete bicarbonate-rich mucus to neutralize gastric acid.

Teniae Coli

Three longitudinal muscle ribbons on colon surface that help form haustra.

Osmotic Diarrhea

Water retention in intestine due to unabsorbed solutes (e.g., lactose intolerance).

Secretory Diarrhea

Excessive intestinal secretion of water/electrolytes, often from bacterial toxins.

Transmural Inflammation

Inflammation involving all layers of the bowel wall, characteristic of Crohn’s disease.

Barrett Esophagus

Metaplasia where esophageal squamous epithelium is replaced by intestinal-type columnar cells due to chronic GERD.

Haustra

Bulging pouches of the colon formed by teniae coli contractions (repeat for clarity).

Nitrosamines

Dietary compounds linked to increased stomach cancer risk, especially prevalent in some East Asian diets.