10.6 The Gastrointestinal Tract Part 2 Flashcards
What is the purpose of the lower esophageal sphincter?
prevents reflux of chyme back into the esophagus
What is the purpose of the pyloric sphincter?
prevents the passage of food from the stomach into the duodenum
What is the opening of the pyloric sphincter inhibited?
when the small intestine already has a large load of chyme
What mediates the opening and closing of the pyloric sphincter?
nerves that connect the duodenum and stomach and hormones
What is cholecystokinin?
main hormone secreted by epithelial cells in the duodenum responsible for mediating the opening and closing of the pyloric sphincter
What secretes gastrin?
G cells
What is the function of gastrin?
stimulates acid and pepsin secretion and gastric motility
What stimulates the secretion of gastrin?
food in the stomach and the parasympathetic nervous system
What is histamine and what is its function in the GI tract?
small molecule that binds to parietal cells to stimulate acid release
What are the three segments of the small intestine?
duodenum
jejunum
ileum
What are the three factors that allow for large surface area of the small intestine?
length
villi
microvilli
What are villi?
macroscopic projections into the wall of the small intestine
What are microvilli?
microscopic foldings of the cell membranes of individual epithelial cells
What is the brush border of small intestine?
the lumenal surface of the small intestine
What are intestinal villi?
finger-like projections of the wall into the gut of the lumen
