Saliva

Saliva is a clear liquid that's produced in the mouths of animals, including humans. It's secreted by the salivary glands and has several important functions. Saliva helps to moisten the mouth, initiate digestion, and help with swallowing. It also plays a significant role in maintaining oral health.

Composition

Saliva is composed of 99.5% water, while the remaining 0.5% consists of various substances including electrolytes, mucus, glycoproteins, enzymes, and antibacterial compounds. The enzymes present in saliva are essential in beginning the process of digestion of dietary starches and fats. These enzymes also play a role in breaking down food particles entrapped within dental crevices, thus protecting teeth from bacterial decay.

Functions

Saliva serves several functions in the body. It aids in digestion by moistening food and creating a food bolus, so it can be swallowed easily. Saliva contains the enzymes amylase and lipase. Amylase starts to break down starches into maltose and dextrin, while lipase starts to break down fats. Saliva also serves as a solvent in which solid particles can dissolve in and enter the taste buds located on the tongue. It also has a cleaning action on the teeth, and its alkaline nature can neutralize the acids produced by bacteria that can lead to tooth decay.

Production

Saliva is produced in and secreted from the salivary glands. The basic secretory units of salivary glands are clusters of cells called acini. These cells secrete a fluid that contains water, electrolytes, mucus, and enzymes, all of which flow out of the acinus into collecting ducts.

Clinical significance

Changes in the composition and production of saliva can be a significant factor in disease. Reduced saliva production can lead to dry mouth and increase the risk of gingivitis and tooth decay. Excessive saliva production can be a symptom of various diseases including Parkinson's disease, Bell's palsy, and rabies.

See also

• Dry mouth
• Sialorrhea
• Xerostomia

Saliva Resources
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