Page 928 - Fundamentals of anatomy physiology

Checkpoint Chapter 24 The Digestive System 915

1. Identify the organs of the digestive system. with mucus and saliva; and (4) limited digestion of carbohy-
2. List and define the six primary functions of the drates and lipids.

digestive system. The oral cavity is lined by the oral mucosa, which has
3. What is the importance of the mesenteries? a stratified squamous epithelium. A layer of keratinized cells
4. Name the layers of the gastrointestinal tract beginning covers regions exposed to severe abrasion, such as the superior
surface of the tongue and the opposing surface of the hard pal-
at the surface of the lumen. ate (part of the roof of the mouth). The epithelial lining of the
5. Which is more efficient in propelling intestinal cheeks, lips, and inferior surface of the tongue is relatively thin
and nonkeratinized. Nutrients are not absorbed in the oral cav-
contents from one place to another: peristalsis ity, but the mucosa inferior to the tongue is thin enough and
or segmentation? vascular enough to permit the rapid absorption of lipid-soluble
6. What effect would a drug that blocks parasympathetic drugs. Nitroglycerin may be administered by this route to treat
stimulation of the digestive tract have on peristalsis? acute angina pectoris. p. 725

See the blue Answers tab at the back of the book. The mucosae of the cheeks, or lateral walls of the oral cav-
ity, are supported by pads of fat and the buccinator muscles.
24-2 The oral cavity contains Anteriorly, the mucosa of each cheek is continuous with that of
the lips, or labia (LA. -be. -uh; singular, labium). The vestibule is
the tongue, salivary glands, and teeth, the space between the cheeks (or lips) and the teeth. The gingi-
each with specific functions vae (JIN-ji-ve. ), or gums, are ridges of oral mucosa that surround
the base of each tooth on the alveolar processes of the maxillary
Learning Outcome Discuss the anatomy of the oral cavity, and list the bones and mandible. In most regions, the gingivae are firmly
functions of its major structures and regions. bound to the periostea of the underlying bones. The frenulum
of lower lip is a fold of mucosa that extends from the gingiva to
Let’s continue our exploration of the digestive tract by fol- the lower lip, attaching the lip to the gum.
lowing the path of ingested food. We begin at the oral cavity
(mouth), or buccal (BUK-ul) cavity (Figure 24–6). The func- The hard and soft palates form the roof of the oral cavity.
tions of the oral cavity include (1) sensory analysis of food before The tongue dominates its floor (Figure 24–6b). The floor of
swallowing; (2) mechanical processing through the actions of the the mouth inferior to the tongue gets extra support from the
teeth, tongue, and palatal surfaces; (3) lubrication by mixing

Figure 24–6 The Oral Cavity. ATLAS: Plates 11a; 19

Hard palate Soft palate
Nasal cavity
Hard palate

Palatoglossal Pharyngeal tonsil Soft palate
arch
Entrance to Fauces Uvula 24
Opening of
parotid duct auditory tube Palatoglossal Tongue

Upper lip Nasopharynx arch Openings of
Cheek Uvula Palatopharyngeal submandibular ducts

Dorsum of arch
tongue
Palatine tonsil Palatine
Lower lip
Gingiva Fauces tonsil

Vestibule Palatopharyngeal Lingual
arch frenulum
Body of Oropharynx
tongue Gingiva
Lingual tonsil
Root of Epiglottis Vestibule
tongue
Hyoid bone Frenulum
Laryngopharynx of lower lip

a A sagittal section of the oral cavity

b An anterior view of the oral cavity