Module 5 Flashcards
What is the adventitia called when it’s exposed to the abdominal cavity?
Serosa or visceral peritoneum
What is the lymphoid tissue distributed throughout the GI tract?
GALT
What are the characteristics of the esophagus?
Thick, protective, stratified squamous epithelium
Lamina propria- lymphoid aggregations
Small mucous glands in submucosa
Skeletal muscle in top and middle
Deeply folded when relaxed
Adventitia is continuous with surrounding connective tissue
What type of mucosa does the esophageo-gastric junction transition to?
Highly glandular
What is the function of the stomach?
Mechanical and chemical reduction of food to form chyme
What are rugae?
Prominent longitudinal folds
What are the regions of the stomach?
Cardia
Fundus
Corpus
Pylorus
What are the characteristics of the mucosal zones?
Cardia- mucous secreting glands
Fundus and corpus- straight tubular glands in gastric pits/foveolae, secretion of gastric juice (HCl and pepsin) and some protective mucous
Pylorus- simple, branched, coiled tubular glands secreted mucous, endocrine glands secrete gastrin
What types of cells are present in gastric glands?
Mucous secreting- luminal surface, some in neck of glands
Parietal/oxyntic- HCl secretion along length of glands, intrinsic factor production (VitB12)
Peptic/chief- base of gland, cytoplasm contains pepsinogen (activated in lumen by gastric juices)
What is the name of the endocrine cells that secrete gastrin?
G-cells
What type of mucosa does the gastro-duodenal junction transition to?
Villous arrangement
What is the primary function of the small intestine?
Digestive product absorption
What are the parts of the small intestine?
Duodenum
Jejunum
Ileum
What types of digestion occurs in the small intestine?
Luminal- mixing chyme and pancreatic enzymes
Membrane- enzymes within luminal plasma membranes of cells lining the intestine
What increases the surface area of the small intestine?
Length (4-6m)
Plicae circulares
Villi- crypts of Lieberkuhn
Microvilli
Where are the Peyer’s patches found?
Lamina propria
What happens in the Peyer’s patches?
Sampled Ags are received and production of IgA is stimulated
What are the characteristics of the villi?
Simple, columnar epithelium
Enterocytes- membrane digestion and absorption
Goblet cells- mucous secreting
Paneth cells in clusters at the base of the crypts, major source of lysozyme
What are the secretory functions of the duodenum?
Chyme stimulates Brunner’s glands to secrete thin alkaline mucous- neutralizes chyme to protect mucosa, compound coiled branched tubular glands in submucosa
Chyme stimulates release of secretin and CCK from endocrine cells, stimulates pancreatic secretion and gall bladder secretion (CCK)
What type of mucosa does the ileo-caecal junction transition to?
Glandular form
What types of cells are found in the large intestine?
Absorptive- tall columnar cells, micro villi increases SA for water absorption
Goblet- basally located, mucous secreting
What does the commensal bacteria in the large intestine do?
Further degrades food residues
What is the rectum?
Longitudinal layer of muscularis that forms three bands (teniae coli)
What is the appendix and its function?
Blind ending extension of the caecum
Masses of lymphoid tissue in the mucosal and submucosal layers
Secrete IgA
What type of mucosa does the recto-anal junction transition to?
Stratified squamous epithelium
Skin with sebaceous and large apocrine sweat glands
What are the layers of the GI tract?
Mucosa- epithelial lining, lamina propria, muscularis mucosae
Submucosa
Muscularis/muscularis propria- inner circular layer and outer longitudinal layer
Adventitia
