The salivary glands in 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. Salivary glands can be classified as serous, mucous or seromucous (mixed).

In serous secretions, the main type of protein secreted is alpha-amylase, an enzyme that breaks down starch into maltose and glucose, whereas in mucous secretions the main protein secreted is mucin, which acts as a lubricant.

In humans, between 0.5 and 1.5 litres of saliva are produced every day. The secretion of saliva (salivation) is mediated by parasympathetic stimulation; acetylcholine is the active neurotransmitter and binds to muscarinic receptors in the glands, leading to increased salivation.

The fourth pair of salivary glands, the tubarial glands discovered in 2020 are named for their location, being positioned in front and over the torus tubarius. However, this finding from one study has to be confirmed.

 

Note:   The above text is excerpted from the Wikipedia article Salivary gland, which has been released under the GNU Free Documentation License.