Final

• Two main groups of organs

  1. Alimentary canal (gastrointestinal or GI tract)
  2. Accessory digestive organs
• Alimentary canal (gastrointestinal or GI tract)

  • continuous coiled hollow tube
  • These organs ingest, digest, absorb, defecate
• Accessory digestive organs

  Includes teeth, tongue, and other large digestive organs
• •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 projection of the soft palate
• Vestibule — space between lips externally and teeth and gums internally
• Oral cavity proper — area contained by the teeth
• Tongue — attached at hyoid bone and styloid processes of the skull, and by the lingual frenulum to the floor of the mouth
• Palatine — located at posterior end of oral cavity
• Lingual — located at the base of the tongue
• Mastication - Process of chewing the food
• Mouth Physiology

  1. Mastication (chewing) of food
  2. Mixing masticated food with saliva
  3. Initiation of swallowing by the tongue
  4. Allows for the sense of taste
• Nasopharynx — not part of the digestive system
• Oropharynx — a part of the pharynx that is posterior to oral cavity
• Laryngopharynx — a part of the pharynx that is located below the oropharynx and connected to the esophagus
• Pharynx - Serves as a passageway for air and food
• In the Pharynx, food is propelled to the esophagus by two muscle layers

  1. Longitudinal inner layer
  2. Circular outer layer
• In the pharynx, food movement is by alternating contractions of the muscle layers (peristalsis)
• How many inches is esophagus?

  10 inches
• Esophagus - runs from pharynx to stomach through the diaphragm
• Esophagus Physiology

  1. Conducts food by peristalsis (slow rhythmic squeezing)
  2. Passageway for food only (respiratory system branches off after the pharynx)
• Four layers of tissue in the Alimentary Canal from deep to superficial

  1. Mucosa
  2. Submucosa
  3. Muscularis externa
  4. Serosa
• Mucosa - Innermost, moist membrane consisting of

  1. Surface epithelium
  2. Small amount of connective tissue (lamina propria)
  3. Small smooth muscle layer
• Mucosa lines the cavity (known as the lumen)
• Submucosa

  • Just beneath the mucosa
  • Soft connective tissue with blood vessels, nerve endings, mucosa-associated lymphoid tissue, and lymphatics
• Muscularis externa — smooth muscle

  Inner circular layer

  Outer longitudinal layer
• Serosa — outermost layer of the wall contains fluid-producing cells
• Visceral peritoneum — outermost layer that is continuous with the innermost layer
• Parietal peritoneum — innermost layer that lines the abdominopelvic cavity
• Regions of the stomach

  1. Cardiac region
  2. Fundus
  3. Body
  4. Pylorus
• Cardiac region — A region in the stomach that is near the heart
• Fundus — region of the stomach that is an expanded portion lateral to the cardiac region
• Body — midportion region of the stomach
• Pylorus— a region of the stomach that is funnel-shaped terminal end
• Rugae — internal folds of the mucosa in the stomach
• Stomach can stretch and hold 4 L (1 gallon) of food when full
• External regions

  1. Lesser curvature — concave medial surface
  2. Greater curvature — convex lateral surface