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Saliva on a baby's lips. Saliva (commonly referred to as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth.In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be extracted), enzymes (such as lipase and amylase), and antimicrobial agents (such as secretory IgA, and lysozymes).
Each acinus consists of a single layer of cuboidal epithelial cells surrounding a lumen, a central opening where the saliva is deposited after being produced by the secretory cells. The three forms of acini are classified in terms of the type of epithelial cell present and the secretory product being produced - serous, mucoserous, and mucous.
The secretory acinar cells of the submandibular gland have distinct functions. The mucous cells are the most active and therefore the major product of the submandibular glands is saliva which is mucoid in nature. Mucous cells secrete mucin which aids in the lubrication of the food bolus as it travels through the esophagus.
The striated ducts are also numerous and consist of simple columnar epithelium, having striations that represent the infolded basal cell membranes and mitochondria. [ 8 ] : 273 Though the parotid gland is the largest, it provides only 25% of the total salivary volume.
It consists of loose connective tissue within the connective tissue papillae, along with blood vessels and nerve tissue. The tissue has an equal amount of fibers, cells, and intercellular substance. The dense layer is the deeper layer of the lamina propria. It consists of dense connective tissue with a large amount of fibers.
The chief and parietal cells produce and secrete mucus (F) to protect the lining of the stomach (C) against the harsh pH of stomach acid. The mucus is basic, while the stomach acid (A) is acidic. In the human digestive system , mucus is used as a lubricant for materials that must pass over membranes, e.g., food passing down the esophagus .
In human anatomy, the mouth is the first portion of the alimentary canal that receives food and produces saliva. [2] The oral mucosa is the mucous membrane epithelium lining the inside of the mouth. In addition to its primary role as the beginning of the digestive system, the mouth also plays a significant role in communication.
Saliva also contains a glycoprotein called haptocorrin which is a binding protein to vitamin B 12. [17] It binds with the vitamin in order to carry it safely through the acidic content of the stomach. When it reaches the duodenum, pancreatic enzymes break down the glycoprotein and free the vitamin which then binds with intrinsic factor.