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The digestive system is composed of the gastrointestinal tract—commonly referred to as the GI tract or digestive tract—as well as the liver, pancreas, and gallbladder. The gastrointestinal system is made up of a succession of hollow organs connected by a long, twisting tube that runs from the mouth to the anus. The mouth, esophagus, stomach, small intestine, large intestine, and anus are the hollow organs that comprise the GI tract. The liver, pancreas, and gallbladder are the digestive system’s solid organs (NIDDK, 2019).
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esophagus
A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity. Stratified squamous epithelia usually have protective funtions: protection against easy invasion of underlying tissue by microorganisms and protection against water loss.
The slide shows an example of stratified squamous nonkeratinized epithelia from the esophagus. The surface cells of non-keratinized epithelia are living cells. Non-keratinized surfaces must be kept moist by bodily secretions to prevent them from drying out. They usually secrete mucus as an additional protective and lubricating layer which is why they are seen in the esophagus and in parts of the female reproductive system.