Objective 78: The Alimentary Canal

Distinguish among the different parts (gross and histological) of the alimentary canal in terms of structure and function.................

This picture from the Anatomy and Physiology textbook* explains the basic layers of all portions of the alimentary canal.  One of the greatest hurdles to overcome with the alimentary canal is the understanding that while all layers have an internal epithelium for the mucosa, each of those layers will have a different type of epithelium that relates to the structures function.  For example the mouth and esophagus have an epithelium layer of stratified squamous to protect them from abrasion.  The stomach and the small intestine are both lined with simple columnar epithelium yet the stomach epithelium is designed for secretion of gastric juices while the small intestines epithelium is designed for absorption.

Nurse's Note: Damage to the stomach's epithelial lining can lead to gastric ulcers which can cause severe stomach pain.  Once thought to be caused by certain medications and ingesting spicey food, the H.Pylori bacteria is now thought to be the most common cause.