GASTRO-ESOPHAGEAL (CARDIAC) SPHINCTER
Function: Prevents backflow of food into the esophagus.
Characteristics: Cardiac sphincter at junction changes from stratified squamous to simple columnar.
Characteristics: Divided into 4 layers: mucosa, submucosa, muscularis externa and serosa. The mucosa is the innermost layer of the gastrointestinal tract that is surrounding the lumen, or space within the tube. This layer comes in direct contact with food (or bolus), and is responsible for absorption and secretion. Mucosa is further divided into epithelium, lamina propia and muscularis mucosae.
Function: Submucosa consists of a dense irregular layer of CT with large blood vessels, lymphatic, and nerves. Muscularis externa consists of an inner circular layer and a longitudinal outer muscular layer. Adventitia consists of several layers of epithelia.
Location: Large Intestine.
the oral mucosa is the mucous membrane epithelium of the mouth. It can be divided into 3 categories:
- Masticatory mucosa: keratinized stratified squamous epithelium, found on the dorsum of the tongue, hard palate and attached gingiva.
- Lining mucosa: Non-keratinized stratified squamous epithelium, found almost everywhere else in the oral cavity.
- Specialized mucosa: Specifically in the regions of the taste buds on teh dorsum of the tongue.
Location: Oral Cavity.
CRYPTS OF LIEBERKUHN
Function: Production of digestive enzymes (e.g. sucrase, maltase, and endopeptidases).
Characteristics: Composed of simple columnar cells, goblet cells, DNES, and Paneth cells; tubular glands.
Location: Small and large intestines.