Gastrointestinal Tract Flashcards
Mucosa of esophagus
Stratified squamous non-keratinized epithelium –> muscularis mucosa (smooth muscle) –> esophageal glands in sub-mucosa –> circular smooth muscle –> longitudinal smooth muscle
Muscularis externa of esophagus
Circular skeletal muscle (distal) –> skeletal and smooth muscle (middle) –> longitudinal smooth muscle (distal)
Esophago-gastric junction
This is where the lining of the mucosa changes from stratified squamous to simple columnar epithelium. Contains some goblet cells
Cardiac stomach
Shallow gastric pits and cardiac glands. Lined by mucous columnar cells
Fundus and body stomach
Gastric pits and gastric glands. The glands are branched tubular.
Rugae
Large mucosa and submucosa folds in the stomach
Pyloric stomach
End of the stomach that contains deep gastric pits and short pyloric glands which are coiled tubular branched. Represents the transition from stomach to duodenum. Secretes mostly mucous
Surface mucous cells
Stomach. Secretes protective mucous
Mucous neck cells
Stomach. Secretes mucous
Parietal cells
Stomach. Light stained, eosinophilic, and secrete HCl and intrinsic factor
Chief cells
Stomach. Dark stained, basophilic, secrete pepsinogen
G cells
Secrete gastrin, hormonal function
Enteroendocrine cells (stomach)
Secrete serotonin
Active parietal cells
Contain microvilli that have filled up the intracellular canaliculi, and Golgi
Resting parietal cells
Contain tubulovesicles and empty intracellular canaliculi
Gastro-duodenal junction
Transition from the stomach to the intestine. There is a change in mucosa from gastric pits to intestinal villi. Smooth muscle of the pyloric sphincter can be seen
Enterocyte
Mature absorptive cell of the GI tract. Contains a terminal web
Goblet cells
Protective cell that secretes mucous for lubrication. Located in the upper gland of small intestine
Enteroendocrine cells (small intestine)
Located in the lower gland of crypts
Paneth cells
Located in base of glands in the small intestine. Innate immunity. Eosinophilic cells with dark granules.
Regions of the small intestine
Duodenum –> jejunem –> ileum
Duodenum
Villi on the surface, intestinal glands (short crypts of Lieberkuhn), and Brunner’s glands. Can contain the plicae circularis
Jejunem
Contains surface villi and crypts of Lieberkuhn. Also contains the plicae circularis
Ileum
Contains surface villi, crypts of Lieberkuhn and Peyer’s patches. Location where most bile salts are reabsorbed back into the portal circulation.
Micovillus of small intestine
Increases surface area and stores digestive enzymes
Peyer’s patches
Located in the ileum. Lymphatic nodules that increase the area where absorption can occur.
Structure of large intestine
Cecum -> ascending column -> transverse column -> descending column -> sigmoid column -> rectum
Appendix
Location for an accumulation of debris that is cleaned out by the lymphatic system, attached to the cecum. Contains dense lymphatic nodules
Teniae coli
3 longitudinal bands of smooth muscle in the muscularis externa of large intestine. Forms the distinct bumps of the colon
Recto-anal junction
Change from simple columnar in the rectum to stratified squamous in the anus. There are abundant goblet cells in the rectum.
Peristaltic movement
Downward movement of material. More prevalent in the intestines than the esophagus
Intestinal villi
Contain blood vessels, lacteal, lamina propria, enterocytes and actin. Absorption
Intestinal crypts
Contain paneth cells, enteroendocrine cells, goblet cells, smooth muscle, and lymphocytes. Secretion
Absorptive cell
Absorb and process digestion products of small intestine. Microvillus brush border and numerous cytoplasmic organelles.
Auerbach’s plexus
located in the muscularis externa in the small intestine. Also called the myenteric plexus
Myenteric plexus
Major nerve supply to the GI tract. Controls muscle contraction
Brunner’s glands
Branched tubular glands of the submucosa of duodenum
Plicae circularis
Extension of the submucosa that gives characteristic folds. Most prevalent in the jejunum but can be found in the duodenum too.
Colon
Responsible for water absorption of feces
