Stomach tissue, also called gastric tissue, forms the stomach organ. The stomach is composed of many layers of tissue and glands, and it is an essential part of digestion, which provides fuel for proper functioning of the rest of the body.
The first layer of tissue in the stomach, from inside to outside, is classified as epithelial tissue. The cells in epithelial tissue are tightly packed and form layered sheets. This layer of tissue helps to keep all of the organs separate and in place. Epithelial tissue also protects the organs. This tissue is not only in the stomach, but it can also be found surrounding the body's organs, in the outer layer of the skin, and on the inside of the mouth.
The glands of the stomach are formed in deep pits of the epithelial layer of stomach tissue. The different glands are named after the part of the stomach they belong to. The cardiac glands are located at the cardia, between the esophagus and the body of the stomach. The pyloric glands are in the pylorus section of the stomach, beneath the body of the stomach. The fundic glands are in the fundus, which is at the top of the stomach.
Just outside the epithelial tissue is the lamina propria. This is a thin layer of loose connective tissue that contains a moist lining of mucous membranes. Together with the epithelial tissue, it makes up the mucosa, which secretes gastric acid to aid in digestion. It also absorbs nutrients from the stomach.
The next layer is called the submucosa. It is located outside of the mucosa and is made of fibrous connective tissue, including collagenous and elastic fibers. Fibrous connective tissue is mostly made of proteins and water, and ligaments and tendons are also made of it. In the stomach, its primary purpose is to separate the mucosa from the smooth muscle layer of the stomach wall.
After the layers of muscle tissue called the muscular externa comes the serosa. This is the last layer of the stomach wall, and it is composed of connective tissue. It connects to the serous membrane and is the lining that protects most of the organs within the abdomen.