1. Chapter 17: The Digestive System
VERY Basic
Chapter 17: The Digestive System

2. But first… A video

3. Alimentary Canal Extends from the mouth to the anus Accessory organs
Pharynx
Esophagus
Stomach
Small and large intestine
Rectum
Anus
Accessory organs
Salivary glands
Liver
Gall bladder
Pancreas

4. Layers of the Wall Mucosa (mucous membrane) Submucosa Muscular layer
Epithelium, connective tissue and smooth muscle
Secretion and absorption
Submucosa
Loose connective tissue, blood vessels, lymphatic vessels, nerves
Nourishment, transport absorbed materials
Muscular layer
Smooth muscle in circular and longitudinal groups
Movement of the tube and its contents
Serosa
Epithelium, connective tissue
Protection

5. Movements of the Alimentary Canal
Mixing
Segmentation
Peristalsis

6. Mouth Site of both mechanical and chemical digestion
Teeth and chewing (mastication)

7. Mouth Tongue: root, body Uvula – extension of soft palate
Lingual frenulum
Uvula – extension of soft palate
Division between the pharynx and the nasal cavity
Tonsils (lymphatic tissue)
Palatine
Lingual
Pharyngeal

8. Teeth Incisor Canine Premolar Molar Adult has 32 teeth (permanent)
Children have 20 teeth (deciduous)

9. Pharynx and Esophagus
Neither are involved in digestion
Epiglottis

10. Pharynx
Connects the nasal and oral cavities with the larynx and esophagus
Skeletal muscles control swallowing
Under voluntary control

11. Swallowing 3 stages: Food is chewed and mixed with saliva
Formation of a bolus
Food is pushed to the pharynx to enter the esophagus
Triggers a swallowing reflex
Peristalsis transports food from esophagus to stomach

12. Esophagus Connects mouth to stomach Lined with mucous glands
Cardiac sphincter (Lower esophageal sphincter)

13. Recap Food enters the mouth…then what?
What types of digestion takes place?
What organs/structures are involved?
Is it voluntary or involuntary?

14. Stomach Receives food from the esophagus Digestion
Muscle fibers run in all directions
Circular
Longitudinal
Oblique
Very minimal absorption

15. Stomach Inner lining: rugae – thick folds Greater curvature
Lesser curvature
Regions of the stomach:
Cardia
Fundus
Body
Pylorus
Pyloric sphincter

16. Stomach
As the food is digested, it changes from a bolus (from the mouth and esophagus) to chyme
Chyme
Semifluid paste
Food mixed with digestive enzymes

18. Accessory Organs
Pancreas
Liver
Gall Bladder

19. Pancreas Secretion of pancreas juice Aids in digestion of
Carbohydrates
Fats
Protein
Nucleic acid

20. Liver
Multi lobed
Makes bile
Digestion of fats

21. Liver

22. Gall Bladder Connected to the liver
Storage and release of bile into small intestine

23. Small Intestine Fills most of the abdominal cavity 5.5 – 6 meters long
Receives secretions from pancreas, liver
Absorption

24. Small Intestine Duodenum Jejunum Ileum Vascular Thicker wall
High number of lymph nodes (Peyer’s patches)

25. Small Intestine Mesentary Greater omentum
Connective tissue around the small intestine
Greater omentum
Membrane drapes over lower digestive tract
If infection occurs, omentum will seal off portion of digestive system
Prevents spread of infection to abdominal cavity

26. Greater Omentum

27. Small Intestine
Villi
Projections to increase surface area

28. Large Intestine Joins small intestine at the ileum
Water and electrolyte absorption
Formation of feces

29. Large Intestine Cecum Colon: Rectum Anus
Appendix – projection from cecum
Colon:
Ascending
Transverse
Descending
Sigmoid
Rectum
Anus

32. Digestive Enzyme Table

33. Digestive System Dissection