The digestive system is one of the organ systems of the body, and it is mainly involved in the digestion and absorption of the nutrients consumed. The various parts of the digestive system include:

Esophagus: It is a long, tube-like structure that connects the pharynx with the stomach. It acts as a pathway for the food to travel into the stomach.
Gallbladder: It stores bile juice and secretes it when stimulated in the duodenum.
Lesser omentum: It is the mesentery between the superior part of the liver and the shorter, concave part of the stomach.
Liver: It secretes a liquid called bile juice that aids in the breakdown of fats in the food.
Cecum: It is marked as the beginning of the large intestine.
Vermiform appendix: It is a thin, tube-like structure that remains connected to the cecum and does not have any function.
Rectum: As the absorption of food occurs within the small intestine, the waste moves into the rectum where it is stored temporarily. Subsequently, the wastes [as feces] are expelled from the body through the anus.

The abdomen region includes digestive organs such as stomach, liver, pancreas, gallbladder, large intestine, and small intestine. The following are some of the parts of the abdomen:

Greater omentum: The abdomen is the region between the thorax and the pelvis. The greater omentum is the largest fold of the peritoneum [the serous membrane lining the abdominal cavity], which is composed of connective tissues.
Transverse colon: This colon is a long, tube-like organ that expels water from the food and forms stool. The colon has four parts: ascending colon, transverse colon, descending colon, and sigmoid colon. The transverse colon is the longest region of the colon in the abdomen. The ingested food particles travel into the transverse colon through the ascending colon.
Mesentery: It is a fan-shaped dual fold of peritoneal tissue that aids in the storage of fats.
Sigmoid colon: It is the part of the colon [large intestine] that is close to the anus and rectum. It is an S-shaped region that plays an important role in the expulsion of gaseous and solid wastes.

Salivary glands are one of the exocrine glands of the body that produce a liquid called saliva. There are three major paired salivary glands in the human body:

Parotid gland: The two parotid glands in the human body aid in swallowing and chewing. The parotid duct brings the parotid gland's secretions into the oral cavity.
Submandibular gland: This gland is located below the lower jaws. The submandibular ducts bring saliva released from the submandibular gland under the tongue.
Sublingual glands: These glands are present under the tongue. Two such glands are found in the human mouth. The sublingual ducts bring saliva released from the sublingual glands under the tongue.