HSC 4551 Lecture Notes - Lecture 7: Paracetamol, Colostomy, Metaplasia
Document Summary
Long muscular tube that propels food down to the stomach. Lined by stratified squamous epithelium to withstand wear and tear. Either end there is a muscular sphincter. Circular band of smooth muscle that serves to close an opening. May not open adequately or close properly. Can be restricted by food or carcinoma. Closes to keep food in the stomach to mix with digestive enzymes before entering the duodenum. Produces hydrochloric acid, pepsin (protein-digesting enzyme), and mucus (protects the lining from the hydrochloric acid and other enzymes) Discomfort that gets worse after eating, lying down, or bending over. Cardiac sphincter does not close properly and there is regurgitation of gastric juices up into the esophagus. Causes esophageal stratified squamous epithelium to undergo metaplstic changes. Metaplasia is when epithelium changes from one type of epithelium to another. Changes to mucous producing columnar epithelium to protect the esophageal tissues. Patients with this have a greater risk of developing esophageal adenocarcinoma.
