The Digestive System
I. Functional Anatomy of the Digestive System
The digestive system is generally divided into the Alimentary Canal: Mouth,
Pharynx, Esophagus, Stomach, Small and Large Intestines, (the tubes and
cavities in which food passes) and Accessory Structures: Salivary Glands,
Teeth, Liver, Pancreas, and Gallbladder.
Digestive Processes:
1. Ingestion-food intake
2. Propulsion-peristalsis ( movement of food)
3. Mechanical digestion-chewing, churning, segmentation
4. Chemical digestion-Chemical catabolism of food
5. Absorption: absorption of food and drink
6. Defecation: elimination of unwanted material
Histology of the Alimentary Canal. Four regions.( innermost to outermost)
1. Mucosa: Epithelial layer, Lamina propria, Muscularis mucosae
2. Submucosa Dense irregular connective and glands
3. Muscularis externa: Inner circular smooth muscle, Outer longitudinal
smooth muscle
4. Serosa: Connective tissue, outer epithelial layer. Continuous with the
mesentery
, The Mouth
1. Also called the Oral cavity or Buccal cavity
2. Boundaries are: a) Anterior –The Lips, b) Posterior- the
Oropharynx, c) Superiorly- the Hard and Soft Palate, and d)
Inferiorly- the Tongue
3. Stratified epithelium of the Gums, the Hard Palate and the Dorsum
of the Tongue are slightly keratinized.
The Tongue
1. Intrinsic muscles-confined to the tongue, not attached to bone.
2. Extrinsic muscles- extend to the tongue from their point of origin on
bone
3. Lingual frenelum-attaches the tongue to the floor of the mouth.
4. Papillae-peglike projections
a. Filiform papillae- smallest and most numerous type. Has a
whitish hue due to keratin.
b. Fungiform papillae- “taste buds” scattered throughout the
tongue. Mushroom shaped elevations containing five taste buds
each
c. Circumvallate papillae- tongue has 10 to 12 of these in a V
shaped row. Contains 100 to 300 taste buds.
, d. Sulcus terminale-a groove delinating the anterior from the
posterior portions of the tongue
5. The lingual tonsil consists of nodular “bumps” posterior to the
sulcus terminale
6. The tongue posses approximately 10,000 taste buds. Each taste
bud is an oval shaped body consisting of 50 to 100 epithelial cells.
7. Five basic qualities to taste. Sweet, Sour, Salty, Bitter, and Umami.
Salivary Glands (Accessory Structures): secrete saliva into the oral cavity
1. The Parotid Gland-anterior to the Ear.
2. Submandibular Gland
3. Sublingual
Teeth ( Accessory)
1. Deciduous
2. Permanent-up to 32 teeth. Eight incisors, Four Canines, Eight
Bicuspids, and Twelve Molars.
3. Structure.
I. Functional Anatomy of the Digestive System
The digestive system is generally divided into the Alimentary Canal: Mouth,
Pharynx, Esophagus, Stomach, Small and Large Intestines, (the tubes and
cavities in which food passes) and Accessory Structures: Salivary Glands,
Teeth, Liver, Pancreas, and Gallbladder.
Digestive Processes:
1. Ingestion-food intake
2. Propulsion-peristalsis ( movement of food)
3. Mechanical digestion-chewing, churning, segmentation
4. Chemical digestion-Chemical catabolism of food
5. Absorption: absorption of food and drink
6. Defecation: elimination of unwanted material
Histology of the Alimentary Canal. Four regions.( innermost to outermost)
1. Mucosa: Epithelial layer, Lamina propria, Muscularis mucosae
2. Submucosa Dense irregular connective and glands
3. Muscularis externa: Inner circular smooth muscle, Outer longitudinal
smooth muscle
4. Serosa: Connective tissue, outer epithelial layer. Continuous with the
mesentery
, The Mouth
1. Also called the Oral cavity or Buccal cavity
2. Boundaries are: a) Anterior –The Lips, b) Posterior- the
Oropharynx, c) Superiorly- the Hard and Soft Palate, and d)
Inferiorly- the Tongue
3. Stratified epithelium of the Gums, the Hard Palate and the Dorsum
of the Tongue are slightly keratinized.
The Tongue
1. Intrinsic muscles-confined to the tongue, not attached to bone.
2. Extrinsic muscles- extend to the tongue from their point of origin on
bone
3. Lingual frenelum-attaches the tongue to the floor of the mouth.
4. Papillae-peglike projections
a. Filiform papillae- smallest and most numerous type. Has a
whitish hue due to keratin.
b. Fungiform papillae- “taste buds” scattered throughout the
tongue. Mushroom shaped elevations containing five taste buds
each
c. Circumvallate papillae- tongue has 10 to 12 of these in a V
shaped row. Contains 100 to 300 taste buds.
, d. Sulcus terminale-a groove delinating the anterior from the
posterior portions of the tongue
5. The lingual tonsil consists of nodular “bumps” posterior to the
sulcus terminale
6. The tongue posses approximately 10,000 taste buds. Each taste
bud is an oval shaped body consisting of 50 to 100 epithelial cells.
7. Five basic qualities to taste. Sweet, Sour, Salty, Bitter, and Umami.
Salivary Glands (Accessory Structures): secrete saliva into the oral cavity
1. The Parotid Gland-anterior to the Ear.
2. Submandibular Gland
3. Sublingual
Teeth ( Accessory)
1. Deciduous
2. Permanent-up to 32 teeth. Eight incisors, Four Canines, Eight
Bicuspids, and Twelve Molars.
3. Structure.
