The submucosa is a layer of connective tissue located beneath the mucosa in various organs of the body, including the digestive tract. It provides structural support and contains blood vessels, nerves, and lymphatics, which help supply nutrients and facilitate communication within the organ. In the gastrointestinal tract, the submucosa plays a crucial role in maintaining the integrity of the mucosal layer and supporting its functions. It also contains the submucosal plexus, a network of nerves that regulates digestive processes, such as enzyme secretion and blood flow, ensuring efficient nutrient absorption.