Oral Glands

1. Oral Glands • Oral glands are a diverse set of glands that secrete water or mucous into the food. • Reptilian oral glands (loosely termed salivary glands) include the premaxillary, palatine, nasal, lacrimal, Duvernoy's, Harderian, sublingual, lingual, infralabial, and mandibular glands. • Oral glands are lost or very reduced in aquatic species. The notable exceptions are the sea snakes and crocodilians. • The infra-labial, supra-labial, lingual, sublingual, premaxillary-, nasal-, and palatine glands produce mucus which lubricates the mouth and aids in food transport.

2. The lacrimal and Harderian glands lubricate the eyes and vomero-nasal organs via ducts that connect the eyes to the mouth. • In many snakes , there are several salivary glands throughout the mouth that not only moisten food but that may keep the mucous membranes of the mouth healthy, neutralize prey toxins, and that may have some digestive function.  • Duvernoyâs gland found in many snakes along the posterior upper lip and secretes through a duct adjacent to the posterior maxillary teeth and gives rise to the venom gland.  The venom gland secretes a cocktail of many different chemicals with many different functions.  Some of the chemicals are digestive enzymes, proteolytic ones, while others include the various types of toxins found in snakes.  The venom is a way to start the insides of the prey digesting.  • Fishes and aquatic tetrapods tend to have few or no oral glands because they do not need to moisten their food, because its already wet. 

4. Oral gland secretions : • Saliva : • Lubrication and binding: the mucus in saliva is extremely effective in binding masticated food into a slippery bolus that (usually) slides easily through the esophagus without inflicting damage to the mucosa. Solubilizes dry food: in order to be tasted (by taste buds), the molecules in food must be solubilized. • Oral hygiene: The oral cavity is almost constantly flushed with saliva, which floats away food debris and keeps the mouth relatively clean. Saliva also contains lysozyme, that lyses many bacteria and prevents overgrowth of oral microbial populations. • Initiates starch digestion: in most species, amylase is present in saliva and begins to digest dietary starch into maltose. Amylase does not occur in the saliva of carnivores. • Provides alkaline buffering and fluid: this is of great importance in ruminants, which have non-secretory forestomachs. • Evaporative cooling: clearly of importance in dogs, which have very poorly developed sweat glands - look at a dog panting after a long run and this function will be clear.

5. poison : lizards and snakes. • anticoagulant : Vampire bats.

6. SALIVARY GLANDS: There are types of salivary glands: • (i) PAROTID: The two parotid glands are located at each side of the mouth cavity and empty their secretions into the mouth through short ducts. • (ii) SUBLINGUAL : located in the floor of the mouth. • (iii) SUBMAXILLARY: Below and behind the sublingual salivary gland. -These glands produce and secrete saliva continuously. - moistens, lubricates and softens food for swallowing - in all cases, the glands open up into the mouth cavity by means of ducts. - they produce about 1.0 - 1.5 L of saliva/day - saliva has a pH of about 6.0 - 7.4. -saliva is 99% water, 0.2% ions and 0.8% enzymes - it contains an antimicrobial agent (thiocyanate ion) together with other special enzymes that prevent infection by pathogenic microorganisms .