For the four layers of the GI, explain how these layers are modified in the esophagus.
Mucosa - Stratified squamous epithelium. Also have in the lamina propria, mucosal glands which are called cardiac glands.
Submucosa - contains esophageal glands.
Muscularis - Upper third of the esophagus is skeletal muscle. The middle third is a mix of skeletal and smooth muscle. The lower third is smooth muscle. The skeletal muscles are associated with the voluntary act of swallowing.
Adventitia/Serosa - above the diaphragm it is adventitia, and below the diaphragm it is serosa.
Note: the mucous glands in the mucosa and submucosa both lubricate the surface of the esophagus.