Study Notes on Digestive System Disorders

Chapter 17 - Digestive System Disorders

Date: October 20, 2025

Learning Objectives

  • Describe the pathophysiology, signs, and possible complications of acute pancreatitis.

  • Explain how gluten toxicity may affect individuals with celiac disease.

  • Describe the signs of malabsorption.

  • Compare Crohn disease with ulcerative colitis.

  • Describe the stages in the development of acute appendicitis and the signs associated with each stage.

  • Explain how diverticulosis and diverticulitis develop.

  • Describe the common causes of intestinal obstruction.

  • Explain the progressive effects of intestinal obstruction and the related signs.

  • Differentiate chemical peritonitis from bacterial peritonitis, including causes for each.

  • Describe the pathophysiology of peritonitis and possible complications.

Overview of the Digestive System

  • Most digestion occurs in the small intestine.

  • The digestive system includes various organs:

    • Mouth: Chews food to mix with saliva.

    • Esophagus: Transports swallowed food to the stomach.

    • Stomach: Mixes and dilutes chyme; secretes gastric juice.

    • Small Intestine: Major site for nutrient absorption; receives bile and pancreatic secretions.

    • Large Intestine: Absorbs water and electrolytes; prepares for fecal elimination.

    • Rectum: Stores feces until defecation.

  • Anatomy includes:

    • Hard palate, parotid salivary gland, sublingual salivary gland, liver, gallbladder, pancreas, and different segments of the intestine (duodenum, jejunum, ileum, and colon).

Disorders and Manifestations

Common Digestive System Disorders

Anorexia & Nausea

  • Anorexia: Lack of appetite associated with multiple disorders.

  • Nausea: Stimulated by the following factors:

    • Distention, irritation, and inflammation of the digestive tract.

    • Smells, visual images, pain, and chemical toxins or drugs.

Vomiting

  • Mechanism: Reflex mechanism controlled by the medulla.

  • Can lead to metabolic acidosis if prolonged due to dehydration.

  • Effects:

    • Dehydration, alkalosis/acidosis, and malnutrition.

  • Characteristics of Vomitus:

    • Hematemeis: Blood in vomit, indicative of hemorrhage; can present as coffee grounds if digested.

    • Color variations indicate bleed source:

    • Yellow/green (bile), dark brown (lower intestine).

Diarrhea

  • Definition: Excessive frequency of stools, often loose or watery.

  • Types:

    • Large volume (secretory or osmotic) – related to infections.

    • Small volume – indicative of inflammatory bowel disease (IBD), often contains blood.

    • Steatorrhea: Fatty diarrhea seen in malabsorption syndromes such as cystic fibrosis and celiac disease.

Blood in Stool

  • Frank blood: Fresh blood, associated with rectal or anal lesions (e.g., hemorrhoids).

  • Occult blood: Hidden blood found through laboratory tests, indicating possible upper GI bleeds (e.g., ulcers).

  • Melena: Dark, tarry stool resulting from significant upper GI bleeding.

Pain Types

  • Somatic Pain: Originates from skin, muscles, and soft tissues, well-localized.

  • Visceral Pain: Arises from internal organs, poorly localized and diffuse.

  • Referred Pain: Pain felt in a location other than the site of injury due to interconnected sensory nerves.

Dysphagia

  • Definition: Difficulty swallowing.

  • Causes:

    • Neurological disorders (e.g., stroke), muscular disorders (e.g., muscular dystrophy), and mechanical obstructions (e.g., tumors).

  • Manifestations: Pain when swallowing, inability to swallow solid materials progressing to liquids.

Malnutrition

  • Definition: Insufficient intake of nutrients resulting from poor digestion and absorption.

  • Types:

    • Limited malnutrition involves one or two nutrient deficiencies (e.g., vitamin B₁₂ leading to pernicious anemia).

    • General malnutrition affects multiple nutrients and can arise from eating disorders, chronic vomiting, diarrhea, or small intestine disorders.

Basic Diagnostic Tests

  • Radiography: Use of contrast mediums may highlight abnormalities.

  • Ultrasound: Detects unusual masses.

  • CT and MRI scans: For detailed imaging of digestive organs.

  • Fiberoptic Endoscopy: Used for biopsy and examination of GI tract.

  • Laboratory Analysis: Stool tests for infection/bleeding, blood tests for liver and pancreatic function.

Upper Gastrointestinal Tract Disorders

Hiatal Hernia

  • Definition: Part of the stomach protrudes into the thoracic cavity through the diaphragm.

  • Types:

    • Sliding Hernia: More common, involves movement of the stomach junction above the diaphragm.

    • Paraesophageal Hernia: Part of the fundus moves through, potential for trapped food and inflammation.

  • Symptoms: Heartburn, substernal pain, frequent belching, discomfort when lying down.

  • Management: Smaller, frequent meals help reduce discomfort.

Pyloric Stenosis

  • Definition: Narrowing and obstruction of the pyloric sphincter.

  • Congenital: Presents in infants with projectile vomiting after feeding.

  • Acquired Forms: Occur in adults, linked to delicate fibrotic tissue or tumors.

Gastroesophageal Reflux Disease (GERD)

  • Cause: Reflux of gastric contents causing esophageal erosion and inflammation.

  • Predisposing Factors: Weakened lower esophageal sphincter (LES), frequently associated with hiatal hernia.

Gastritis

  • Acute Gastritis: Inflammation of the gastric mucosa, usually self-limiting.

  • Chronic Gastritis: Long-term inflammation leading to atrophy and potential cancer.

    • Caused by factors like H. pylori infection, spicy food, alcohol, and NSAID use.

  • Symptoms: Anorexia, nausea, vomiting, hematemesis, epigastric discomfort.

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Gastroenteritis

  • Definition: Inflammation of stomach and intestines, often due to infections.

  • Symptoms: Diarrhea, nausea, vomiting.

  • Recovery: Most infections are self-limiting, with similar manifestations to other GI disorders.