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Chapter 14 – Part 1 The Digestive System

Chapter 14 – Part 1 The Digestive System. INTRODUCTION VIDEO. 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

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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

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