There are two types of glands.Two salivary glands and pancreas.
its found in the epidermal layer of the skin
You are probably referring to the accessory organs of digestion, and there are several. The liver, gallbladder, pancreas, and salivary glands.
Mucous-secreting glands are primarily found in epithelial tissues. These glands are commonly located in the respiratory tract, digestive tract, and certain parts of the reproductive system. For example, goblet cells in the respiratory and intestinal epithelium secrete mucus to protect and lubricate surfaces. Additionally, mucous glands can be found in salivary glands and the gastric mucosa of the stomach.
There are far too many to mention, but would include the brain, lungs, kidneys, liver, etc. If you are asking about organs that are related to the digestive process, then you are probably referring to the accessory organs of digestion, and there are several. The liver, gallbladder, pancreas, and salivary glands are probably the major ones, though this list could also be endless if you consider the special senses.
Technically, most named digestive enzymes and secretions are made by glands located outside of the "tube" of the gastrointestinal tract. For instance, the salivary glands are located between the muscles of the jaw and face, and secrete saliva into the mouth through salivary ducts. Bile is created by the liver, stored in the gallbladder and then secreted into the small intestine; pancreatic enzymes (there are a bunch of them) are made in the pancreas then secreted into the small intestine as well.
Anus
Annelids
Stomach
There are a number of organs involved in excretion: the lower digestive tract including the colon, the kidneys, the lungs, and the sweat glands. The lower digestive tract removes or excretes indigestible items from the digestive tract. The kidneys remove urea which is a product of the breakdown of proteins. The lungs remove carbon dioxide which is also a waste product. And the sweat glands remove excess water.
The digestive tract is considered to be outside the body in terms of its function. It is a continuous tube that runs from the mouth to the anus, and while it is enclosed within the body, it is technically an external environment because it is open to the outside at both ends. The substances that enter the digestive tract are not part of the body's internal environment until they are absorbed into the bloodstream.
Cellulose is digested by cellulase.It is not found in human.
The mouth contains the buccal mucosa-- which contains the openings of the salivary glands, the tongue, and the teeth.