Mucosa
Inner lining of the GIT, is a mucous membrane. It is composed of (1) a layer pf epithelium in direct contact with the contents of the GIT, (2) a layer of connective tissue called the lamina propria, and (3) a thin layer pf smooth muscle (muscularis mucosae)

Function: The functions of mucosa is absorption and secretion. It contains specialized goblet cells that secrete sticky mucus throughout the GIT.

Submucosa
Consist of areolar connective tissue that binds the mucosa to the muscularis. It contains many blood and lymphatic vessels that receive absorbed food molecules. Also located in the submucosa is an extensive network of neurons known as the submucosal plexus. The submucosa may also contain glands and lymphatic tissue.

Function:
In the gastrointestinal tract, the submucosa is the layer of dense, irregular connective tissue or loose connective tissue that supports the mucosa, as well as joins the mucosa to he bull of underlying smooth muscle (fibers that run circularly within s layer of longitudinal muscle.

Muscularis
Of the mouth, pharynx, and superior and middle parts of the esophagus contains skeletals muscle that produces vontary swallowing. Skeletal muscle also forms the external anal sphincter, which permits voluntary control of desfecston. Throughout the rest of the tract, the muscularis consists of smooth muscle that is generally found in two sheets : an inner sheet of circular fibers and outer sheet of longitudinal fibers.

Function:
The muscularis is responsible for the segmental contractions and peristaltic movementss in the gastrointal tract.

Serosa
The portion of the GIT that are suspended in the abdomino pelvic cavity have a susperficial layer, as its mame implieas, the serosa is a serous menebrane composed of Areolar, the tissue and simple aquamouss epithelium (mesothelium)

Function:
Serous membranes lines and enclose several body cavities, known as serous cavities, where they secretes a lubricating fluid to reduce friction from muscle movements.