Consists of the alimentary canal and its principal associated organs, including the tongue, teeth, salivary glands, pancreas, liver, and gallbladder
Major functions include transport of ingested water and food, secretion of fluids and digestive enzymes, digestion and absorption of digested products, and excretion of indigestible remains
Alimentary canal
The lumen is physically and functionally external to the body
Digestion
1. Food is broken down physically and chemically so that the degraded products can be absorbed into the body
2. The various segments of the alimentary canal are morphologically specialized for specific aspects of digestion and absorption
Approximately 2 L of water and food are ingested into the body each day
Ingestion and preliminary processing
1. Food is macerated, moistened, and formed into a bolus by the oral cavity and salivary glands
2. Food passes rapidly through the pharynx to the esophagus
Digestion and absorption
1. Food passes more slowly through the gastrointestinal tract, aided by digestive juices
2. Most fluids and nutrients are absorbed chiefly through the wall of the small intestine, with a small portion absorbed in the large intestine
Excretion
Undigested food and other substances within the alimentary canal, such as mucus, bacteria, desquamated cells, and bile pigments are excreted as solids (feces)
Alimentarymucosa
Performs functions including secretion, absorption, barrier, and immunologicprotection
Oral cavity
Consists of the mouth and its structures, including the tongue, teeth and supporting structures, major and minor salivary glands, and tonsils
Vestibule
The space between the lips, cheeks, and teeth
Oralcavityproper
The space behind the teeth, bounded by the hard and softpalates, tongue, floor of the mouth, and entrance to the oropharynx
Major salivary glands
Parotid
Submandibular
Sublingual
Parotid gland
Largest of the three major salivary glands, located in the infratemporal region
Excretory duct (Stensen'sduct) opens at the parotidpapilla on the cheek
Submandibulargland
Located in the submandibulartriangle of the neck
Excretory duct (Wharton's duct) opens at the sublingualcaruncle on the floor of the oral cavity
Sublingual gland
Located inferior to the tongue within the sublingual folds
Has multiple small excretory ducts that enter the submandibular duct or the oral cavity directly
Digestive system
Consists of the alimentary canal and its principal associated organs, including the tongue, teeth, salivary glands, pancreas, liver, and gallbladder
Major functions include transport of ingested water and food, secretion of fluids and digestive enzymes, digestion and absorption of digested products, and excretion of indigestible remains
Alimentary canal
The lumen is physically and functionally external to the body
Digestion
1. Food is broken down physically and chemically so that the degraded products can be absorbed into the body
2. The various segments of the alimentary canal are morphologically specialized for specific aspects of digestion and absorption
Approximately 2 L of water and food are ingested into the body each day
Ingestion and preliminary processing
1. Food is macerated, moistened, and formed into a bolus by the oral cavity and salivary glands
2. Food passes rapidly through the pharynx to the esophagus
Digestion and absorption
1. Food passes more slowly through the gastrointestinal tract, aided by digestive juices
2. Most fluids and nutrients are absorbed chiefly through the wall of the small intestine, with a small portion absorbed in the large intestine
Excretion
Undigested food and other substances within the alimentary canal, such as mucus, bacteria, desquamated cells, and bile pigments are excreted as solids (feces)
Alimentary mucosa
Performs functions including secretion, absorption, barrier, and immunologic protection
Oral cavity
Consists of the mouth and its structures, including the tongue, teeth and supporting structures, major and minor salivary glands, and tonsils
Vestibule
The space between the lips, cheeks, and teeth
Oral cavity proper
The space behind the teeth, bounded by the hard and soft palates, tongue, floor of the mouth, and entrance to the oropharynx
Major salivary glands
Parotid
Submandibular
Sublingual
Parotid gland
Largest of the three major salivary glands, located in the infratemporal region
Excretory duct (Stensen's duct) opens at the parotid papilla on the cheek
Submandibular gland
Located in the submandibular triangle of the neck
Excretory duct (Wharton's duct) opens at the sublingual caruncle on the floor of the oral cavity
Sublingual gland
Located inferior to the tongue within the sublingual folds
Has multiple small excretory ducts that enter the submandibular duct or the oral cavity directly
Minor salivary glands
Buccal
Labial
Lingual
Palatine
Tonsils
Aggregations of lymphatic nodules clustered around the posterior opening of the oral and nasal cavities
Tonsillar (Waldeyer's) ring
Palatine tonsils
Tubal tonsils
Pharyngeal tonsil (adenoid)
Lingual tonsil
Oral mucosa
Consists of masticatory mucosa, lining mucosa, and specialized mucosa
Masticatory mucosa
Found on the gingiva and hard palate
Has a keratinized or parakeratinized stratified squamous epithelium
Lamina propria is thick with papillae and blends with the periosteum, lacking a submucosa
Lining mucosa
Found on the lips, cheeks, alveolar surface, floor of mouth, inferior tongue, and soft palate
Epithelium is generally non-keratinized, with fewer and shorter papillae to allow for movement
Distinct submucosa underlies the lining mucosa, containing blood vessels, nerves, and minor salivary glands
Fordyce spots are sebaceous glands found in the submucosa just lateral to the corner of the mouth and opposite the molar teeth
Filiform papillae
Mechanical papillae distributed over the entire anterior dorsal surface of the tongue, with tips pointing backward
Fungiform papillae
Mushroom-shaped projections scattered among the filiform papillae, more numerous near the tongue tip
Contain taste buds
Circumvallate papillae
Large, dome-shaped structures located just anterior to the sulcus terminalis, surrounded by a moat-like invagination containing numerous taste buds
Ducts of lingual salivary (von Ebner's) glands empty into the moat