Physiology: small intestine & exocrine pancreas Flashcards
what are the 3 parts of the small intestine
duodenum, ileum and jejunum
what does the small intestine receive
chyme from stomach, pancreatic juice from pancreas and bile from liver + gall bladder
what is the main function of the small intestine
major site for digestion and absorption, and secrets intestinal juice
what does motility of the small intestine cause
mixing of chyme with digestive juices, slow propulsion of chyme and removal of undigested residues to large intestine
in what ways is the small intestine well adapted for absorption
increased surface area due to circular folds, villi and microvilli(brush border)
in what state does segmentation occur
in the digestive state
describe the action of segmentation
‘chopping’ moves chyme back and fourth vigorously, by alternating contractions and relaxation of segments of smooth muscle
what is segmentation initiated by
small intestine pacemaker cells causing the basic electrical rhythm(BER), which is continuous, to reach threshold
describe effect of sympathetic and parasympathetic activity on segmentation
sympathetic = decreased strength parasympathetic = increased strength
at what speed does segmentation occur
movement is slow, takes 3-5hours, allows time for absorption
in what state does peristalsis occur
the interdigestive state, or fasting state
describe the Migrating Motor Complex(MMC) involved peristalsis
strong peristaltic contractions slowly passing through the intestine
what is the function of peristalsis
clears small intestine of debris, mucus and epithelial cells between meals(‘housekeeper’ function)
what is peristalsis inhibited and suppressed by
inhibited = feeding and vagal activity suppressed = gastrin and CCK
what is peristalsis triggered by
motilin
