Shier, Butler, and Lewis:
Hole’s Human Anatomy and Physiology, 10
Digestion is the breakdown of foods into forms that cell membranes can
Mechanical digestion breaks large pieces of food into smaller ones without
altering their chemical composition.
Chemical digestion breaks down food into simpler chemicals.
The organs of the digestive system carry out the processes of ingestion,
propulsion, absorptions, defecation, and digestion.
The alimentary canal is composed of the mouth, pharynx, esophagus, stomach,
small intestine, large intestine, and anal canal.
The accessory organs of the digestive system are salivary glands, liver,
gallbladder, and pancreas.
General Characteristics of the Alimentary Canal
The alimentary canal is a muscular tube that passes through the body’s
The structure of its wall, how it moves food, and its innervation are
similar throughout its length.
Structure of the Wall
The four layers of the alimentary wall are the mucosa, submucosa,
muscular layer, and serosa.
The mucosa is located as the inner lining and is composed of epithelial
tissue, a small amount of connective tissue, and some smooth muscle.
The functions of the mucosa are to secrete mucus and enzymes, and to
The submucosa is located deep to the mucosa and is composed of loose
connective tissue, glands, blood vessels, lymphatic vessels, and nerves.