GI Anatomy and Overview

• Oral cavity, pharynx, esophagus, stomach, liver, pancreas, small and large intestines
• Neural and hormonal control: Low pH in stomach aids digestion and prevents infection

Stomach Anatomy and Function

Stomach Zones

• Cardiac Zone
• Gastric Zone
  • Parietal cells produce HCl
    • Stimulated by caffeine, alcohol, stress, etc.
  • Chief cells secrete pepsinogen (becomes pepsin with acid)
  • Mucus cells provide protective coating
• Pyloric Zone

Stomach Secretions

• Acidic pH
• Hydrochloric acid
• Bicarbonate
• Pepsinogen
• Salivary amylase
• Intrinsic factor
• Mucus
• Prostaglandins

Parietal Cells

• Receptors: Acetylcholine, Histamine, Gastrin
• Proton pump utilizes ATP and calcium ions

GI Functions

• Digestion and absorption of carbohydrates, proteins, and lipids
• Fat and water-soluble vitamins, electrolytes, drugs, water

Common Digestive Disorders

Eating Disorders

• Anorexia and Bulimia
  • Severe electrolyte imbalances affecting systemic health
• Vomiting: Coordinated by medulla, can be triggered by various factors

Bowel Disorders

• Constipation: Caused by various factors including narcotics and aging
• Diarrhea: Can be acute or chronic, caused by infections, medications, and more

Laxatives and Antidiarrheals

Types of Laxatives

• Bulk forming, Emollient, Hyperosmotic, Saline, Stimulant

Antidiarrheals

• Adsorbents, Antimotility drugs (opiates and anticholinergics), Probiotics

Specific Conditions

IBS (Irritable Bowel Syndrome)

• Types: IBS-D, IBS-C, IBS-M
• Treatment focuses on symptom management

GERD (Gastroesophageal Reflux Disease)

• Symptoms include heartburn, acid regurgitation
• Treatment with antacids, H2 blockers, PPIs

PUD (Peptic Ulcer Disease)

• Caused by H. pylori, NSAIDs, stress
• Treatment involves PPIs, antibiotics, and lifestyle changes

Medications

Antacids

• Neutralize stomach acid, may contain salts of aluminum, magnesium, calcium

H2-Receptor Blockers

• Ex: Famotidine - Block histamine from H2 receptors to reduce acid

Proton Pump Inhibitors (PPIs)

• Block H+/K+ ATPase enzyme, reduce gastric acid
• Ex: Omeprazole, Pantoprazole

Antiemetics

• Anticholinergics: Ex: Scopolamine
• Serotonin blockers: Ex: Ondansetron (Zofran)
• Prokinetics: Ex: Metoclopramide (Reglan)
• Cannabinoids: Ex: Dronabinol for chemo-induced N/V
• Neurokinin blockers: Ex: Apreptinant

Pediatric GI Issues

• Esophageal Atresia: Congenital anomaly of the esophagus
• Pyloric Stenosis: Narrowing of the pylorus in infants
• Intussusception: Intestinal obstruction in children
• Celiac Disease: Gluten intolerance
• Failure to Thrive: Inadequate physical development
• Necrotizing Enterocolitis: Bowel necrosis in neonates

Diarrhea Management in Children

• Keep child home, monitor skin and I/O, encourage fluids and electrolytes