<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (November 2011) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (November 2011) (Learn how and when to remove this template message) </Td> </Tr> <P> Saliva is a watery substance formed in the mouths of animals, secreted by the salivary glands . Human saliva comprises 98% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be extracted), glycoproteins, enzymes (such as amylase and lipase), antimicrobial agents such as secretory IgA and lysozyme . The enzymes found 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 . Furthermore, saliva serves a lubricative function, wetting food and permitting the initiation of swallowing, and protecting the mucosal surfaces of the oral cavity from desiccation . </P> <P> Various animal species have special uses for saliva that go beyond predigestion . Some swifts use their gummy saliva to build nests . Aerodramus nests form the basis of bird's nest soup . Cobras, vipers, and certain other members of the venom clade hunt with venomous saliva injected by fangs . Some caterpillars, produce silk fiber from salivary glands . </P>

Where does saliva come from in the mouth