GIT 1 Flashcards
What components are included in the lac operon?
Regulatory gene
Promoter region
Operator region
3 structural genes (B-galactosidase, permease, B-galactoside)
How can GIT infections like giardia cause lactose intolerance?
Giardial infections damage GIT epithelial cells (brush border of SI), causing them to slough off. They’re replaced by immature cells w/ low lactase concentration. The malabsorbed lactose is fermented by bacteria in the LI – diarrhea, flatulence, bloating, cramps.
What 2 mechanisms regulate the lac operon?
1) Binding of repressor protein to operator region – repressor protein constitutively expressed, prevents RNAp binding to promoter; lactose induces shape change in repressor protein.
2) cAMP-CAP binding upstream from promotor – glucose dec. adenyl cyclase activity, dec. cAMP inhibits CAP binding.
What are the DDx for bilious emesis in neonates? (3)
Midgut volvulus, intestinal stenosis, intestinal atresia.
*Bilious emesis in neonates is due to intestinal obstruction below 2nd part of duodenum.
Atresias of the midgut are usually caused by occlusion of a major artery (SMA). How does it appear on imaging?
“Apple peel/Christmas tree”
Proximal segment ends in blind pouch, ff. by an area of absent bowel (necrosis), and distal segment has spiral configuration around around a vascular stalk (artery).
Pathogenesis of Umbilical hernias.
Normally, the umbilical ring closes to form the midline fibrous tissue of the linea alba. Incomplete closure allows protrusion of bowel to create umbilical hernia. Most are reducible and resolve spontaneously.
Appendicitis pain: from periumbilical area to RLQ (McBurney point)
Visceral pain (dull, non-localized) around periumbilicus due to afferent fibers entering SC at T10 – continued inflammation irritates parietal peritoneum – somatic (severe, localized) pain shifts to McBurney point.
