Digestion Process: The Mouth

Introduction to the Mouth

• First location for food digestion
• Known as:
  • Mouth (common name)
  • Oral cavity
  • Buccal cavity

Function of the Mouth

• Converts food into a bolus (sphere of food)
• Steps involved:
  1. Mastication (Chewing)
     • Scientific term: Mastication
     • Involves teeth and tongue
  2. Hydrolysis
     • Enzymatic breakdown of macromolecules

Chewing Mechanism

• Teeth: Detailed analysis in another session
• Tongue (Lingula):
  • Composed of extrinsic and intrinsic muscles
  • Extrinsic muscles:
    • Elevate, depress, protrude, and retract the tongue
  • Intrinsic muscles:
    • Change tongue size by shortening, widening, lengthening, and narrowing

Breakdown by Hydrolysis

• Enzymes break down food particles
• Enzymes sourced from glands in the oral cavity

Salivary Glands

1. Parotid Glands
   • Location: Side of the mouth, above the jawbone
   • Contribution: 25% of saliva
   • Main release: Serous content (rich in enzymes)
2. Submandibular Glands
   • Location: Below the mandible (jaw)
   • Contribution: 70% of saliva
   • Main release: Mainly serous, some mucinous
3. Sublingual Glands
   • Location: Below the tongue (lingula)
   • Contribution: 5% of saliva
   • Main release: Mucin (some enzymes)
4. Von Ebner's Gland
   • Location: Tip of the tongue
   • Contribution: <5% of saliva
   • Unique enzyme: Lingual lipase (breaks down triglycerides)

Enzymes in Saliva

• Lingual Lipase
  • Breaks down lipids into free fatty acids and diglycerides/monoglycerides
• Alpha-Amylase
  • Breaks down carbohydrates, like starch, into smaller carbohydrates

Purpose of Digestion in the Mouth

• Not sufficient for nutrient absorption
• Enhances taste perception (e.g., fats in burgers, sugar in sodas)

Impact of Sugar on Oral pH

• Mouth's normal pH: 7.0
• Excess sugar lowers pH < 5.5
• Acidic conditions can demineralize teeth
• Important consideration: Limit sugar intake to prevent tooth damage