Chapter 14 – Part 1 The Digestive System - PowerPoint PPT Presentation

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Chapter 14 – Part 1 The Digestive System

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Chapter 14 – Part 1 The Digestive System

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  1. Chapter 14 – Part 1The Digestive System

  2. INTRODUCTION VIDEO

  3. The Digestive System and Body Metabolism • Digestion • Takes in food (ingests it) • Breaks it down physically and chemically into nutrient molecules (digests it) • Absorbs the nutrients into the bloodstream • Then, it rids the body of the indigestible remains (defecates)

  4. Organs of the Digestive System • 2 GROUPS OF DIGESTIVE SYSTEM ORGANS: • Alimentary canal– continuous coiled hollow tube • Performs the whole menu of digestive functions (ingests, digests, absorbs, and defecates) • Accessory digestive organs • Assists the process of digestive breakdown in various ways • Includes: teeth, tongue, and several large digestive glands

  5. Organs of the Digestive System

  6. The Alimentary Canal • The alimentary canal is also called the gastrointestinal (GI) tract. • Continuous, coiled, hollow, muscular tube that winds through the ventral body cavity • Is open at both ends • Is about 30 feet long in a cadaver

  7. Organs of the Alimentary Canal • Mouth • Pharynx • Esophagus • Stomach • Small intestine • Large intestine • Anus

  8. Mouth (Oral Cavity) Anatomy • Lips (labia) – protect the anterior opening • Cheeks – form the lateral walls • Hard palate – forms the anterior roof • Soft palate – forms the posterior roof • Uvula – fleshy fingerlike projection of the soft palate

  9. Mouth (Oral Cavity) Anatomy • Vestibule – space between lips and cheeks externally and the teeth and gums internally • Oral cavity proper – area contained by the teeth • Tongue – muscle that occupies the floor of the mouth

  10. Mouth (Oral Cavity) Anatomy • Tonsils • Palatine tonsils • Lingual tonsil

  11. Processes of the Mouth • Mastication (chewing) of food • Mixing masticated food with saliva • Initiation of swallowing by the tongue • Allowing for the sense of taste

  12. Pharynx Anatomy • Nasopharynx – not part of the digestive system • Oropharynx – posterior to oral cavity • Laryngopharynx – below the oropharynx and connected to the esophagus

  13. Pharynx Function • Passageway for air and food (oropharynx and laryngopharynx only) • Food is propelled to the esophagus by two muscle layers: • Longitudinal inner layer • Circular outer layer (constrictor muscles) • Food movement is by alternating contractions of the muscle layers • This propelling mechanism is called peristalsis

  14. Esophagus • Runs from pharynx to stomach through the diaphragm • Conducts food by peristalsis(slow rhythmic squeezing) • Passageway for food only (respiratory system branches off after the pharynx) • About 10 inches long

  15. Layers of Alimentary Canal Organs • Mucosa • Innermost layer • Moist membrane • Consists primarily of: • Surface epithelium • Plus a small amount of connective tissue (lamina propria) • Small smooth muscle layer

  16. Layers of Alimentary Canal Organs • Submucosa • Found just beneath the mucosa • Soft connective tissue layer containing blood vessels, nerve endings, lymph nodules, and lymphatic vessels

  17. Layers of Alimentary Canal Organs • Muscularisexterna – • Smooth muscle layer made up of: • Inner circular layer • Outer longitudinal layer • Serosa • Outermost layer – visceral peritoneum • Layer of serous fluid-producing cells

  18. Layers of Alimentary Canal Organs • Serosa • Outermost layer • Consists of a single layer of flat serous fluid-producing cells

  19. Layers of Alimentary Canal Organs