- The salivary glands are a group of exocrine glands in the human body that produce and secrete saliva, a vital fluid that plays a key role in digestion, oral health, and lubrication of the mouth and throat.
- These glands are located in and around the oral cavity and are essential for maintaining the health of the teeth, mucous membranes, and upper gastrointestinal tract. Saliva contains a mixture of water, electrolytes, mucus, enzymes, antibacterial compounds, and immunoglobulins, particularly IgA.
- There are three pairs of major salivary glands: the parotid, submandibular, and sublingual glands, each with distinct anatomical locations and secretory characteristics. The parotid glands are the largest and are located just in front of and below the ears. They produce a serous (watery) type of saliva rich in amylase, an enzyme that begins the breakdown of starches in the mouth. The submandibular glands are situated beneath the lower jaw and secrete a mixed saliva containing both serous and mucous components, making it thicker and more lubricating. The sublingual glands, found under the tongue, primarily produce mucous saliva, which helps in moistening and protecting the oral mucosa.
- In addition to these major glands, there are hundreds of minor salivary glands dispersed throughout the lining of the lips, cheeks, palate, and tongue. These smaller glands contribute continuously to baseline saliva production, keeping the mouth moist and comfortable even in the absence of food stimuli.
- Salivary secretion is controlled by the autonomic nervous system. The parasympathetic nervous system stimulates the glands to produce copious, watery saliva, especially in response to taste, smell, or the thought of food. In contrast, sympathetic stimulation results in the secretion of a thicker, more viscous saliva. Salivation can also be triggered reflexively by mechanical stimuli, such as chewing, or inhibited by stress and dehydration.
- Saliva has multiple important functions. In digestion, it not only begins the chemical breakdown of carbohydrates through salivary amylase but also helps form the bolus, the softened mass of food that is easier to swallow. Lingual lipase, another enzyme secreted by minor glands, begins the digestion of fats in the stomach. Saliva also provides buffering capacity (through bicarbonate), antibacterial protection (via lysozyme, lactoferrin, and immunoglobulins), and contributes to taste perception by dissolving food molecules.
- Disorders of the salivary glands can impair oral function and overall health. Sialadenitis is inflammation of the salivary glands, often caused by bacterial infections or obstruction by salivary stones (sialolithiasis). Sjögren’s syndrome, an autoimmune disease, leads to dry mouth (xerostomia) by attacking salivary glands. Tumors, both benign (like pleomorphic adenomas) and malignant (such as mucoepidermoid carcinoma), can also affect these glands, most commonly the parotid. Chronic dry mouth increases the risk of dental caries, periodontal disease, oral infections, and difficulty in speaking or swallowing.
- In summary, the salivary glands are vital exocrine organs that support digestion, oral hygiene, and mucosal health. Their complex neural regulation and diverse secretory profiles ensure the mouth remains functional and protected in a variety of physiological conditions. Dysfunction of these glands can significantly impact a person’s quality of life, underscoring their importance in both oral and systemic health.
