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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.
Saliva consists of mucus and serous fluid; the serous fluid contains the enzyme amylase, which is important for the digestion of carbohydrates. Minor salivary glands of von Ebner present on the tongue secrete the lipase. The parotid gland produces purely serous saliva. The other major salivary glands produce mixed (serous and mucus) saliva.
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.
Further, because the secretory cells are of both serous and mucous types, the submandibular gland is a mixed gland, and though most of the cells are serous, the exudate is chiefly mucous. It has long striated ducts and short intercalated ducts. [7] The secretory acinar cells of the submandibular gland have distinct functions.
Secretion: Saliva is the primary secretion of the oral mucosa. It has many functions including lubrication, pH buffering and immunity. The lubricating and antimicrobial functions of saliva are maintained mainly by resting; saliva results in a flushing effect and the clearance of oral debris and noxious agents.
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.
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.