Chapter 15. Digestive Tract

This chapter should help the student to:

• Name the parts of the digestive tract and the primary function of each.
• Describe the structure of the tongue, teeth, and gingiva.
• Describe the development of the teeth.
• Compare the digestive tract organs in terms of the four layers comprising their walls and relate any structural variations to differences in organ function.
• Know the distinguishing regional structure of each digestive tract component.
• Name the secretory product(s), the distinguishing structural features, and (where appropriate) the staining properties of each secretory cell type in digestive tract mucosa.
• List the features of the small intestine that promote nutrient absorption and trace the steps in this process.
• Identify the organ, region, cell types present, and type of section (i.e., transverse or longitudinal) in a micrograph of any part of the digestive tract.

1. List the digestive tract organs in the order food passes them (I.A). What happens to the food in each (I.C.1–3)?

2. Sketch a cross-section of a generalized tubular organ of the digestive tract that shows the layered structure of its walls (Fig. 15–1; I.B.1–4) and indicate the location of the following:

1. Lumen

2. Mucosa

3. Submucosa

4. Muscularis externa

5. Serosa

6. Epithelium

7. Lamina propria

8. Muscularis mucosae

9. Submucosal (Meissner's) plexus

10. Myenteric (Auerbach's) plexus

11. Mesothelium

12. Attachment of the mesentery

3. Describe the oral cavity in terms of its epithelial lining, the muscle type in its walls, and the structural difference between the hard and soft palates (II.A).

4. Describe the tongue in terms of its predominant tissue and the epithelium that covers it (II.C).

5. Name the four types of lingual papillae and compare them in terms of their characteristic shape, taste bud distribution, and relative abundance (II.C.1–4).

6. List the four types of teeth (by shape) found in humans (III.A).

7. Compare the “dental formula” for permanent and deciduous teeth (III.B).

8. Sketch a tooth and its surrounding structures in sagittal (midline longitudinal) section (Fig. 15–2) and label the following:

1. Gingiva

2. Alveolar bone

3. Crown

4. Neck

5. Root

6. Apical foramen

7. Enamel

8. Cementum

9. Dentin

10. Pulp

11. Periodontal ligament

12. Epithelial attachment (of Gottlieb; III.D.3)

9. Compare dentin, enamel, and cementum (III.C.5–7) in terms of:

1. Hardness

2. Porosity

3. Collagen content

4. Cell responsible for synthesis

5. Capacity for replacement

10. Describe tooth pulp in terms of its predominant tissue, major cell types, blood supply, and innervation (III.C.4 and 5.b; Fig. 15–2).

11. Describe the periodontal ligament in terms of its composition, location, functions, attachments, and the effects of dietary vitamin C and protein deficiency (III.D.1; Fig. 15–2).

12. Compare ameloblasts, odontoblasts, and cementoblasts in terms of their embryonic origin (III.E), the layer of tooth structure formed by each (III.E), and their survival into adulthood (III.C.5.c, 6.c, and 7).

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