The Mouth: Gateway to Digestion – Anatomy & Function

The mouth (oral cavity) initiates digestion mechanically and chemically.

Structures

• Teeth: Incisors (cut), canines (tear), premolars/molars (grind).
• Tongue: Manipulates food, taste buds, forms bolus, initiates swallowing.
• Salivary glands: Parotid (serous), submandibular (mixed), sublingual (mucous) + minor glands.

Saliva Functions

• Amylase (ptyalin): Starch → maltose (initiates carb digestion).
• Lingual lipase: Triglyceride digestion (important in infants).
• Mucin: Lubricates, forms bolus.
• Antimicrobial: Lysozyme, IgA, peroxidase.
• Buffering: Bicarbonate, phosphate → pH 6–7.

Swallowing

Voluntary oral phase → involuntary pharyngeal/esophageal phases → stomach.

Clinical Relevance

• Xerostomia (dry mouth) → caries, dysphagia, infection risk.
• Oral hygiene prevents systemic bacteremia (endocarditis, pneumonia).