Gastroenterology Essentials: GI Diseases, Medications, and Anatomy

Gastroenterology

Abdominal Quadrants

Key organs located within the four main abdominal quadrants:

• Upper Right (URQ): Liver, Gallbladder
• Upper Left (ULQ): Stomach, Spleen, Pancreas
• Lower Right (LRQ): Appendix, Ascending Colon
• Lower Left (LLQ): Descending and Sigmoid Colon

Gastrointestinal Infections

• Bacterial Infections (e.g., E. coli, Salmonella): Typically characterized by a quicker onset and shorter duration.
• Viral Infections: Generally have a slower onset and longer duration.

Upper GI Disorders

Dyspepsia (Indigestion)

Irritation of the upper GI tract, often presenting as heartburn or a retrosternal burning sensation.

Contributing Factors: Medications, alcohol, caffeine, spicy food, obesity.

Treatment (Rx): Dietary changes, medications.

Gastroesophageal Reflux Disease (GERD)

The backflow of stomach contents into the esophagus. (Note: COX-1 enzyme is typically found in the stomach.)

Contributing Factors: Diet, medications, caffeine, alcohol, stress.

Symptoms: Severe dyspepsia.

Treatment (Rx): Lifestyle modifications, stress management, medications.

Hiatal Hernia

A condition where a portion of the stomach protrudes through a weak spot in the diaphragm. Often associated with Helicobacter pylori.

Symptoms (S&S): Similar to GERD.

Treatment (Rx): Medications, surgery.

Peptic Ulcer Disease

Damage to the submucosal layers in the stomach or duodenal walls.

Etiology: Excessive acids or H. pylori infection.

Symptoms (S&S): Night pain, changes in eating habits.

Treatment (Rx): Medications, avoidance of triggers.

Gastric Acid Production

Gastric acid is produced by parietal cells in the stomach, stimulated by a combination of acetylcholine, histamine, and gastrin.

Upper GI Medications

Antacids

Increase gastric pH (making it less acidic). They are quick-acting and short-lasting, neutralizing existing HCl.

• Aluminum (Alu): Mylanta
• Magnesium (Mg): Phillips' Milk of Magnesia
• Calcium (Ca): Maalox
• Sodium (Na): Alka-Seltzer

Proton Pump Inhibitors (PPIs)

Inhibit the H+ pump (e.g., Nexium, Prilosec), significantly lowering acid production. Long-term use can potentially affect stomach health.

H2 Receptor Antagonists

Limit acid release by inhibiting H2 production (e.g., Tagamet/Cimetidine, Pepcid, Zantac). Indicated for peptic ulcers and dyspepsia.

Lower GI Disorders

Appendicitis

Inflammation of the appendix.

Symptoms (S&S): Epigastric pain migrating to the Lower Right Quadrant (LRQ), nausea, anorexia, fever. Pain localized at McBurney's point.

Treatment (Rx): Surgical removal (appendectomy).

Hemorrhoids

Dilated anal veins caused by straining, constipation, diarrhea, or infection.

Symptoms (S&S): Bleeding, itching.

Treatment (Rx): Pharmaceuticals, diet modification, exercise.

Lower GI Medications

Antidiarrheals

Work by decreasing intestinal transit time or increasing water absorption (the large intestine absorbs water).

• Opioids: Lomotil, Imodium (decrease motility).
• Bismuth Subsalicylate: Pepto-Bismol.
• Note: Absorbents should often be the first option.

Laxatives

Medications used to promote defecation.

• Bulk Formers: Non-digestible plant material (e.g., Psyllium, Methylcellulose).
• Stool Softeners: Allow oil and water to mix into the stool.
• Stimulants: Increase intestinal motility.
• Osmotics: Draw water into the intestines.

Hepatitis and Accessory Organ Conditions

Hepatitis (Viral Liver Inflammation)

• Type A: Transmitted via food or water contamination.
• Types B, C, D: Transmitted via body fluids.

Prevention: Vaccination, hygiene.

Treatment (Rx): Type A often resolves spontaneously. Treatment for Types B, C, and D varies.

Gallstones (Cholelithiasis)

Comprised of cholesterol and bilirubin, causing intermittent pain in the Right Upper Quadrant (RUQ).

Cholecystitis (Gallbladder Disease)

Inflammation of the gallbladder, often due to a buildup of gallstones. Pain may radiate to the right shoulder.

Treatment (Rx): Laparoscopic surgery.

Pancreatitis

Inflammation caused by pancreatic enzymes becoming active within the pancreas itself, resulting in pain in the Left Upper Quadrant (LUQ). This condition can potentially lead to septicemia (bacteria in the bloodstream).