Unit 10 – Introduction to Digestive System Tissues
Introduction to Digestive System Tissues
The digestive system consists of all digestive tract organs involved with ingesting food, digesting food, absorbing the chemically digested products of food, and removing undigested/unabsorbed waste from the body. This includes the mouth (oral cavity) including the teeth and tongue, pharynx (throat), esophagus, stomach, small intestine, and large intestine. Also included in the digestive system are a variety of accessory organs and glands that secrete digestive enzymes, buffers, and/or other substances into the lumen of the digestive tract to facilitate digestion and absorption of nutrients. Accessory organs and glands of the digestive system include the salivary glands, liver, gall bladder, and pancreas.
The tutorials in this unit will focus on the structure and function of the esophagus, stomach, small intestine, and large intestine of the digestive tract proper and several accessory organs of the digestive system including the salivary glands, pancreas, and liver. The chapters that focus on the esophagus, stomach, small intestine, and large intestine will emphasize the structure and function of each organ as well as the histological structure of the four major layers of the digestive tract wall which all segments of the digestive tract have in common.
The four major layers of the digestive tract wall are the mucosa, submucosa, muscularis externa (muscular layer), and either a serosa or adventitia. These four layers demonstrate similar histological and functional characteristics along the entire length of the digestive tract. The image slider below describes the histological characteristics of these four layers and shows numerous examples of the appearance of these layers within different organs of the digestive tract.
