11 Digestive System III-- Small and Large Intestines Flashcards
Where are plicae circulares most pronounced? what are they?
jejunum- permanent semicircular fold of mucosa and SUBMUCOSA
What are the functions of plicae circulares?
3 fold increase in surface area
slow chyme passage
What is the core of villi in small intestines?
lamina propria
What is the function of villi in the intestines?
10 fold increase in surface area
What is found within the lamina propria of a villus?
vein, artery and lacteal
What is the function microvilli?
20 fold increase of surface area
What is the epithelial classification in the small intestine?
simple columnar with microvilli
What is a single cell exocrine gland that protects walls from acidity of chyme and lubricates so contents can flow?
goblet cells—more numerous as you go
What are simple tubular infoldings of the epithelium that extend into the lamina propria?
crypts of lieberkuhn
What transports chylomicrons from the villi to the thoracic duct?
lacteal—>lymphatics—>thoracic duct—>left subclavian
What are the large glands in the submucosa of the duodenum?
brunners
Does the small intestine have a serosa? exception?
yes except for retroperitoneal portion of duodenum
T-F the crypts of lieberkuhn are deep at first and progressively get shorter?
false–opposite is true
What 5 cells can we find in crypts?
enterocytes goblet stem (4-6 just above base) paneth cells enteroendocrine
What do paneth cells secrete?
lysozyme (destroys bacterial peptidoglycan- gram+) and alpha-defensin (destroys bacterial lipid component - gram-)
What are the 3 different types of enteroendocrine cells found in the small intestine?
S-cell
I-cell
enterochromaffin cells
What cell is only in the crypts of the duodenum, release secretin in response to low pH? what effect does this have
S cell– [secretin targets parietal cells to secrete less acid, and centroacinar cells to increase alkaline secretion]
What cell is in the crypts of duodenum and jejunum and release cholecystokinin? what triggers release?
I cell—fat and protein rich chyme triggers
What does cholecystokinin do?
targets pancreatic acinar cells to increase secretion of trypsinogen, also smooth muscle of gallbladder to contract and push bile out
What cells are located in the crypts throughout the intestine and release serotonin in response to food? what does this promote?
enterochromaffin cells– peristalsis
What do brunners glands release?
alkaline solution 8.1-9.3
T-F–the jejunum has both brunners glands and peyers?
False—neither
What does the ileum have that distinguishes it from the rest of the intestines?
M cells and peyers patches
What is the function of an M cell?
entry of antigens and transportation to the peyers patch for immune responses
