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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).
The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. [1] Salivary glands can be classified as serous, mucous, or seromucous (mixed).
The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body.
In the mouth, pharynx and esophagus, pH is typically about 6.8, very weakly acidic. Saliva controls pH in this region of the digestive tract. Salivary amylase is contained in saliva and starts the breakdown of carbohydrates into monosaccharides. Most digestive enzymes are sensitive to pH and will denature in a high or low pH environment.
Neoplastic lesions of the parotid salivary gland can either be benign or malignant. Within the parotid gland, nearly 80% of tumours are benign. [17] Benign lesions tend to be painless, asymptomatic and slow-growing. The most common salivary gland neoplasms in children are hemangiomas, lymphatic malformations, and pleomorphic adenomas. [13]
Exocrine function: The primary role of salivary glands is to produce and secrete saliva into the oral cavity through ducts. This secretion is vital for various digestive processes, including moistening food to aid in swallowing, breaking down complex carbohydrates through the enzyme amylase, and providing lubrication for speech and mastication ...
Saliva moistens the food and begins the digestive process. (Note that horses have no (or negligible amounts of) amylase in their saliva). After being swallowed, the food passes from the esophagus into the stomach, where stomach acid and enzymes help to break down the food.
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.