1. Anatomy & Physiology of Mechanical Digestion ANATOMY & PHYSIOLOGY 13-14

2. Avian Digestive Tract

3. Ruminates

4. Monogastric Digestive System

5. Digestive System Divisions Alimentary Canal (Gastrointestinal Tract) –These are all the structures that food passes through during digestion –One, long, tube open at both ends –Starting with the mouth, ending with the anus Accessory Organs –These are the structures that aid in digestion of food, but in which no food passes –Liver, gallbladder, pancreas, salivary glands

6. Alimentary canal Accessory Organs

7. CONNECTIONS

8. Anatomy of the Oral Cavity

9. Dentition Function: Mastication (chewing) Diphyodont = two sets (20 primary/32 permanent) Forms: –Incisors (8) Cutting and shearing –Canines (4) Gripping and tearing –Premolars (8) Crushing –Molars (12) Grinding

10. Palates Palatum Durum (hard palate): Upper, anterior roof of the mouth, covered with rugae (folds) to allow backwards movement of food Palatum Velum (i.e. “Soft Palate”): Upper, posterior roof of the mouth. Closes off access to nasopharynx during swallowing

11. Anatomy of Tongue Tongue: Muscle that mixes food with saliva, pushes food into the oropharynx, and contains gustatory papillae (taste receptors) Lingual frenulum: Fold of mucous membrane that attaches the tongue to the floor of the mouth

12. Tonsils Lymphoid tissue = first line of immune defense for aerodigestive tract Largest pre- puberty; atrophy after puberty

13. Deglutition and Pharyngeal-Esophageal Anatomy Deglutition = swallowing Food enters into the oropharynx, then passes into the laryngopharynx Closure of the epiglottis allows passage of food into the esophagus and prevents aspiration (particulates in lungs)

14. Peristalsis Alternating contractions between circular and longitudinal muscle of the pharynx and esophagus Physically separates food into small spheres (bolus) and moves it through the esophagus

15. Hiatal Hernia

16. STOMACH Initial site of protein hydrolysis/digestion Primary site of mechanical digestion via rumination Absorption of water and alcohol

17. Dr. William Beaumont and Alexis St. Martin (August 1825)

19. Cardiac Sphincter (antrum cardiacum) Food enters the stomach through this muscle via the esophagus Accidental opening of this structure may lead to Gastro-Esophageal Reflux Disorder (GERD)

20. Fundus Means “bottom” in Latin but is the left anterior curvature of the stomach Stores food for appx. 1 hour Digestive gases collect here

21. Anatomy of Stomach Body Greater and lesser curvature Gastric canal – can hold appx. 1 gallon of food Rugae (increase surface area)

22. Pyloric Antrum & Sphincter Muscular terminus of stomach Involved in rumination of food Food exits the gastric canal via passage through the pyloric sphincter

23. DUODENUM First section of small intestine Drastic rise in pH due to addition of bile salts Receives secretions of pancreas

24. Peptic Ulcers Most common site of ulcers is 5cm distal to pyloric spincter Only 4% of ulcers are stomach Caused by actions of Heliobacter pylori Exacerbated by stress & diet

26. SMALL INTESTINE Jejunum (8ft) Ileum (12ft) Site of absorption and chemical digestion

27. VILLI Small (1mm) projections of small intestine that drastically increase surface area of small intestine Cells lining villi die and are consumed! Contain capillaries for transport of material Contain lacteals to transport fats

28. Vermiform Appendix

29. COLON

30. Colonic Form and Function 1.5m divided into –Ascending –Transverse –Descending –Sigmoid Involved in conduction of solid waste Reabsorption of water via standing gradient osmosis

31. Anal Sphincter Muscular bands that control expulsion of feces Regulated via recto-anal inhibitory reflex (RAIR) Flatuaria is a loss of control over RAIR