03.1 Oesophagus, swallowing and salivation and associated conditions

Oesophagus, Swallowing, and Salivation

• Saliva production: 0.5-1.5 liters daily, mostly water (99%) with proteins and electrolytes (1%)
• Saliva vital for digestion, lubrication, oral hygiene, and teeth remineralization
• Major salivary glands: parotid (serous), submandibular (mixed), and sublingual (mucous)
• Minor salivary glands: 800-1000 throughout the oral cavity, contributing ~10% of total saliva
• Swallowing process: Three phases (oral, pharyngeal, and oesophageal), involving ~30+ muscles and 5 cranial nerves to safely move food/liquid to the stomach

Learning Objectives

• Understand the anatomy and functions of salivary glands
• Describe the physiological stages of swallowing
• Identify and explain common oesophageal disorders (e.g., GERD, dysphagia)

Clinical Applications

• Case study: 70-year-old patient with dry mouth and difficulty swallowing (xerostomia)
• Diagnostic approaches: clinical evaluation, barium swallow, or endoscopy to distinguish obstructive and motor dysphagia
• Treatment options: Hydration, artificial saliva, cholinergic agonists for xerostomia; PPIs, lifestyle changes, or surgery (fundoplication) for GERD
• Complications/Management: Dysphagia can lead to aspiration pneumonia, managed with antibiotics and supportive care. Chronic GERD may cause Barrett's oesophagus (premalignant)

Pathophysiology

• Saliva secretion regulated by autonomic nervous system: parasympathetic increases watery secretion, sympathetic causes thicker, mucous-rich saliva (vasoconstriction).
• GERD mechanism: failure of lower oesophageal sphincter (LES) to prevent reflux of gastric acid into the esophagus causing inflammation (esophagitis), increasing long-term damage (Barrett's oesophagus)

Pharmacology

• Proton Pump Inhibitors (PPIs): Inhibit gastric acid production (often used for GERD), with potential side effects like nutrient malabsorption and increased infection risk
• Cholinergic agonists: Stimulate saliva production for xerostomia, contraindicated in COPD due to potential bronchoconstriction

Differential Diagnosis

• Differentiating GERD from cardiac chest pain (post-prandial GERD pain; cardiac pain often radiating to the left arm and more severe)
• Distinguishing oropharyngeal (difficulty initiating swallowing) vs oesophageal dysphagia (transport issues) - neurodegenerative diseases often present with oropharyngeal dysphagia

Investigations

• Barium Swallow: Evaluates swallowing mechanics and detects obstructions
• Endoscopy: Visualizes esophagitis, strictures, or Barrett's oesophagus in GERD patients

Summary and Key Takeaways

• Saliva critical for digestion, oral hygiene, and speech; regulated by both parasympathetic and sympathetic pathways
• Swallowing a complex process with multiple stages and risks of dysphagia (e.g., aspiration pneumonia)
• GERD arises from lower esophageal sphincter dysfunction, potentially leading to premalignant Barrett's oesophagus

Test your knowledge on the anatomy and functions of the oesophagus, salivary glands, and the swallowing process. This quiz covers the phases of swallowing, salivation, and common oesophageal disorders. Enhance your understanding of clinical applications related to dysphagia and xerostomia.