What is the term for the inner layer of the gastrointestinal tract that is composed of mucous membrane?

The term for the inner layer of the gastrointestinal tract that is composed of a mucous membrane is indeed the mucosa. This layer plays a critical role in digestion and absorption as it contains epithelial cells that secrete mucus and enzymes, aiding in the breakdown of food and facilitating the movement of substances through the gastrointestinal tract. The mucosa also contains specialized cells that produce hormones and offer a protective barrier against pathogens.

In contrast, the submucosa is the layer that lies outside the mucosa, containing connective tissue, blood vessels, and nerves but is not itself composed of mucous membrane. The serosa is the outermost layer of the gastrointestinal tract and is primarily made up of connective tissue. The muscularis is the layer responsible for the contractions that move food through the digestive system but does not have mucous membrane characteristics. Thus, understanding the distinct roles and compositions of these layers highlights why the mucosa is correctly identified as the inner layer that contains the mucous membrane.