Your digestive tract is long, continuous tube that chemically and mechanically digests food. Mechanical digestion describes a mashing or churning action; chemical digestion involves caustic substances that break food down into basic nutrients your body can digest. While the bulk of digestion happens in your stomach and intestines, food begins to digest while it is still in your mouth. The salivary glands are the first organs to digest your food chemically, according to the National Digestive Diseases Information Clearinghouse.
Parotid Gland
Your salivary glands produce saliva which contains an enzyme capable of breaking starches into smaller molecules. According to Colorado State University, most animals have three sets of salivary glands, categorized according to the type of secretion they produce. The two parotid glands are the largest of the salivary glands and produce a serous, or pale yellow and transparent, fluid. These glands are located in each cheek, over the jaw and in front of your ears, and produce about 25 percent of your saliva.
Submandibular and Sublingual Glands
The two other main mouth glands are located in the lower part of the mouth. The submaxillary, or submandibular, gland is located beneath the floor of your mouth. According to Cedars-Sinai Medical Center, this gland produces about 70 percent of your saliva. This gland drains a mixed serous and mucus secretion into your mouth from underneath your tongue through small tubes known as ducts. Your sublingual gland, meanwhile, makes only about 5 percent of saliva. This gland drains predominately mucus secretions into the floor of your mouth.
Ducts
There are about 500 minor glands in your lips, inner cheeks and in the lining of your mouth and throat. The basic units of digestive secretion are clusters of cells called acini, which move a fluid containing water, electrolytes, mucus and digestive enzymes into collection ducts. These ducts alter the composition of the secretions so they better prepare the body and the food for chemical digestion.
Saliva
The first step of chemical digestion, salivation, is controlled by your brain. When you see, smell, taste or even think of food, your salivary glands squirt into action, producing saliva, sometimes called drool. Serous saliva adds moisture to your food while mucus binds chewed foods together to change food into bolus, a slippery concoction that slides down your throat easily. Saliva also makes the molecules in dry food more soluble in water and tastier on the tongue. The acini cells that produce serous secretion also secrete alpha-amylase, which breaks down starches into maltose, a form of starch the body can digest.
