1. The Digestive System and Body Metabolism

2. Digestive System
Accessory organs
Alimentary Canal
Slide 14.2b

3. Organs of the Alimentary Canal
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Explain:
Why the inside of your digestive tract is considered to be “outside”
of you.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

4. 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 projection of the soft palate
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5. 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
Slide 14.7
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6. Pharynx Function Serves as a passageway for air and food
Food is propelled to the esophagus by two muscle layers
Longitudinal inner layer
Circular outer layer
Food movement is by alternating contractions of the muscle layers (peristalsis)
Slide 14.9
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7. 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)
Slide 14.10
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8. Layers of Alimentary Canal Organs
Mucosa
Small smooth muscle layer
2. Submucosa
Soft connective tissue with blood vessels, nerve endings
3. Muscularis externa – smooth muscle
4. Serosa
Outermost layer – visceral peritoneum
Slide 14.11a
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9. Layers of Alimentary Canal Organs
Figure 14.3
Slide 14.13
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10. Choose the answer that lists the four layers of the wall of the alimentary canal in the appropriate order from innermost to outermost.
Mucosa, submucosa, muscularis externa, and serosa
Submucosa, mucosa, serosa, muscularis externa
Serosa, mucosa, muscularis externa, submucosa
Muscularis externa, submucosa, serosa, mucosa
Answer: a. Mucosa, submucosa, muscularis externa, and serosa

11. Stomach Anatomy Cardiac region – near the heart Fundus Body Phylorus
Pyloric Sphincter
Omentum
Slide 14.15a
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12. Specialized Mucosa of the Stomach
Simple columnar epithelium
Mucous neck cells – produce a sticky alkaline mucus
Gastric glands – secrete gastric juice
Chief cells – produce protein-digesting enzymes (pepsinogens)
Parietal cells – produce hydrochloric acid
Endocrine cells – produce gastrin
Slide 14.19
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13. Structure of the Stomach Mucosa
Function of
Pits?
Glands?
Figure 14.4b, c
Slide 14.20b
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14. Stomach Ulcers
H. pylori bacteria
Gastric ulcer lesion

15. Small Intestine: major digestive organ
Pyloric sphincter to the ileocecal valve
“Dogs Just Itch”
Duodenum
Jejunum
Ileum
Slide 14.21

16. Liver Common hepatic duct Bile duct and sphincter
Accessory pancreatic duct
Gallbladder
Pancreas
Jejunum
Hepatopancreatic
ampulla and sphincter
Main pancreatic duct
and sphincter
Duodenum

17. Villi of the Small Intestine: more surface area increased absorption
Figure 14.7a
Slide 14.24
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18. Structures Involved in Absorption of Nutrients
Absorptive cells
Blood capillaries
Lacteals (specialized lymphatic capillaries)
Figure 14.7b
Slide 14.26
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19. Large Intestine: Larger in diameter, but shorter
Absorption of water
Eliminates indigestible food
Does not participate in digestion of food
Goblet cells produce mucus to act as a lubricant
Figure 14.8
Slide 14.28
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20. Functions of the Large Intestine
Absorption of water
Eliminates indigestible food from the body as feces
Does not participate in digestion of food
Goblet cells produce mucus to act as a lubricant
Slide 14.29
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21. Drains blood from the G.I tract to the liver to Vena Cava to Heart
Hepatic Portal System
Drains blood from the G.I tract to the liver to Vena Cava to Heart

22. Accessory Digestive Organs
Salivary glands: forms bolous, amylase
Teeth: masticate (chew), full set is 32 teeth
Pancreas: digestive enzymes secreted into the duodenum, Insulin, Glucagons, neutralize chyme
Liver: Largest gland, connected to the gall bladder , produce bile
Gall bladder: Stores bile- used in lipid digestion
Slide 14.32
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24. Processes of the Digestive System
Peristalsis – alternating waves of contraction
Segmentation – moving materials back and forth to aid in mixing
Figure 14.12
Slide 14.42b
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25. Processes of the Digestive System
Mechanical digestion
Chemical Digestion
Enzymes break down food molecules into their building blocks
Carbohydratesn to simple sugars
Proteins  to amino acids
Fats  to fatty acids and alcohols
Nucleic Acids  to nucleotide
Slide 14.44
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26. Processes of the Digestive System
Absorption
End products of digestion are absorbed in the blood or lymph
Food must enter mucosal cells and then into blood or lymph capillaries
Defecation
Elimination of indigestible substances as feces
Slide 14.45
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27. Control of Digestive Activity
Stimuli include:
Stretch of the organ
pH of the contents
Presence of breakdown products
Reflexes include:
Activation or inhibition of glandular secretions
Smooth muscle activity
Slide 14.47b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings