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Overview of the Digestive System Components

Explore the functions and anatomy of the oral cavity, teeth, salivary glands, pharynx, esophagus, and stomach within the digestive system. Learn about mastication, swallowing process, and stomach functions.

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Overview of the Digestive System Components

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  1. Chapter 24, part 2 The Digestive System

  2. SECTION 24-2The Oral Cavity

  3. The mouth opens into the oral or buccal cavity • Its functions include: • Analysis of material before swallowing • Mechanical processing by the teeth, tongue, and palatal surfaces • Lubrication • Limited digestion

  4. Oral cavity • Lined by oral mucosa • Roof of cavity = hard and soft palates • Floor of cavity = tongue • Uvula guards opening to pharynx

  5. Figure 24.6 The Oral Cavity Figure 24.6a, b

  6. The tongue • primary functions include: • Mechanical processing • Assistance in chewing and swallowing • Sensory analysis by touch, temperature, and taste receptors

  7. Tongue movements involve • Extrinsic and intrinsic tongue muscles • Innervated by the hypoglossal nerve

  8. Salivary glands (three pairs) • Parotid, sublingual, and submandibular • Saliva • watery solution • electrolytes, buffers, glycoproteins, antibodies, enzymes • Functions include: • Lubrication, moistening, and dissolving • Initiation of digestion of complex carbohydrates PLAY Animation: Mastication Flythrough

  9. Figure 24.7 The Salivary Glands Figure 24.7a, b

  10. Teeth • Function in mastication of bolus • Contact of occlusal surfaces • Contain three layers • Enamel covering crown • Dentin forms basic structure • Root coated with cementum • Periodontal ligaments hold teeth in alveoli

  11. Eruption of teeth • 20 primary teeth AKA deciduous teeth • 32 teeth of secondary dentition

  12. Figure 24.8 Teeth Figure 24.8a, b

  13. Figure 24.9 Primary and Secondary Teeth Figure 24.9a, b

  14. SECTION 24-3The Pharynx

  15. The pharynx • Common passageway for food, liquids, and air • Lined with stratified squamous epithelium • Pharyngeal muscles assist in swallowing • Pharyngeal constrictor muscles • Palatal muscles

  16. SECTION 24-4The Esophagus

  17. The esophagus • Carries solids and liquids from the pharynx to the stomach • Passes through esophageal hiatus in diaphragm • The wall of the esophagus contains mucosal, submucosal, and muscularis layers

  18. Histology of the esophagus • Distinctive features of the esophageal wall include • Nonkeratinized, stratified squamous epithelium • Folded mucosa and submucosa • Mucous secretions by esophageal glands • A muscularis with both smooth and skeletal muscle portions • Lacks serosa • Anchored by an adventitia

  19. Figure 24.10 The Esophagus Figure 24.10a-c

  20. Swallowing (deglutition) • Buccal phase • Pharyngeal phase • Esophageal phase

  21. Figure 24.11 The Swallowing Process Figure 24.11a-h

  22. SECTION 24-5The Stomach

  23. Functions of the stomach • Bulk storage of undigested food • Mechanical breakdown of food • Disruption of chemical bonds via acids and enzymes • Production of intrinsic factor

  24. Anatomy of the stomach • Cardia – superior, medial portion • Fundus – portion superior to stomach-esophageal junction • Body – area between the fundus and the curve of the J • Pylorus – antrum and pyloric canal adjacent to the duodenum

  25. Stomach anatomy • Phloric Sphincter • Guards exit from stomach • Rugae • Ridges and folds in relaxed stomach

  26. Figure 24.12 The Stomach Figure 24.12b

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