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Chapter 24, part 2

Chapter 24, part 2. The Digestive System. SECTION 24-2 The Oral Cavity. 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.

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Chapter 24, part 2

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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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