Flashcards in GI Deck (187)
What is derived from the foregut?
Foregut - Pharynx to duodenum, liver, gallbladder, pancreas
Midgut - Duodenum to transverse colon
Hindgut - Distal transverse colon to rectum
What is gastroschisis?
Congenital malformation of the anterior abdominal wall causing extrusion of abdominal contents.
Not covered by peritoneum
What is an omphalocele?
Failure of intestines to return to body cavity after herniation into the umbilical cord. Covered by peritoneum
What causes intestinal atresia?
Duodenal atresia - failure to recanalize
Jejunal, ileal, colonic atresia - vascular accident in-utero
Vascular accident can cause apple peel syndrome where distal atrophic gut is wrapped around an artery.
When does midgut rotation occur?
6th week --> midgut herniates through umbilical ring
10th week --> abdominal cavity is large enough & midgut returns to it & rotates around SMA
Failure can cause malrotation of midgut or omphalocele
What are the possible types of tracheoesophageal abnormalities?
Which is most common?
Most common is EA with distal TEF
Pure TEF (H-type; fistula present but esophagus still patent)
What is seen with EA+TEF?
Choking with first feeding
Cyanosis (laryngospasm to prevent reflux aspiration)
Air in the stomach on CXR
Failure to pass NG tube into stomach
What can result from malformation of the pancreas?
Annular pancreas - ventral pancreatic bud encircles 2nd part of duodenum & may cause narrowing. Due to failure of migration.
Pancreas divisum - Common; dorsal & ventral buds fail to fuse so that most pancreatic acini drain to minor sphincter. Predisposes to chronic pancreatitis.
From where does the spleen arise?
Arises from mesoderm but is supplied by foregut (celiac artery)
The other gut structures are all endodermal.
What are the retroperitoneal structures?
Aorta & IVC
Duodenum (2nd & 3rd parts)
Pancreas (except tail)
Colon (ascending & descending)
Esophagus (lower 2/3)
Rectum (lower 2/3)
What is the falciform ligament?
Connects the liver to the anterior abdominal wall
Contains ligamentum teres (derivative of fetal umbilical vein)
What ligament contains the portal triad?
Portal triad = hepatic artery, portal vein, common bile duct
What is the difference between an erosion and an ulcer?
Erosion = mucosa only
Ulcer = submucosa or deeper
What is the frequency of electrical rhythm along the GI tract?
Stomach = 3 waves/min
Duodenum = 12 waves/min
Ileum = 8 waves/min
What are the layers of the gut wall?
1) Mucosa (epithelium, lamina propria, muscularis mucosa)
2) Submucosa (includes Submucosal/Meissner's plexus)
3) Muscularis externa (includes Myenteric/Auerbach's plexus)
4) Serosa (intraperitoneal) or Adventitia (retroperitoneal)
What is the duodenum composed of histologically?
Villi & microvilli
Brunner's glands (unique to duodenum; HCO3-)
Crypts of Lieberkuhn (throughout small & large intestine)
What is the histology of the ileum?
Peyer's patches (unique to ileum)
Largest # of goblet cells in SI
Plicae circularis (along with jejunum)
Crypts of Lieberkuhn
What can result from failure of the vitelline (omphalomesenteric) duct to obliterate?
When should it obliterate?
Persistent vitelline duct
Should obliterate during the 7th week
What does an acid fast stain bind to?
Mycolic acid (TB, Nocardia)
What can cause papillary necrosis?
Sickle cell disease or trait
When is a child at risk for hemolytic disease of the newborn?
Anti-A or Anti-B Ig's are formed early in life. If a mother is A or B, she will form IgM (cannot cross placenta). If she is O, she will form IgG (can cross placenta). Thus, even her first child is at risk.
Mothers must be inoculated (with the first birth) against Rh. Subsequent births are at risk.
What is the difference in mechanism between unfractionated heparin and LMW heparin?
Unfractionated heparin binds Xa & IIa equally
LMW heparin preferentially binds Xa
*Antithrombin is needed in both cases to form the ternary inactive complex (heparin, AT, Xa/IIa)
What is the function of human Placental Lactogen (hPL)?
Insulin resistance --> fetus gets more of the glucose
^Lipolysis, proteolysis --> energy for both mom & fetus
hPL levels rise throughout gestation to support a growing fetus
What can be seen as a side effect of massive amounts of blood transfusions?
If a patient gets an entire body content of blood (5L) in under 24h, citrate from the blood products (additive) can accumulate and chelate the blood calcium causing hypocalcemia.
Where do the nitrogen atoms in urea come from?
Free NH3 (alanine cycle)
Aspartate (added into the urea cycle)
How id carbamoyl phosphate synthetase I regulated?
Rate-limiting enzyme in the urea cycle
It is activated by N-acetylglutamate
What physical exam findings are more specific for iron deficiency anemia?
Spoon nails (koilonychia)
What growth factors are responsible for angiogenesis?
This is true both in granulation tissue & in tumorgenesis
What is the receptor for rabies virus in the body?
Nicotinic ACh receptor