220.A 39-year-old woman presents with dyspnea, fatigue, pallor, tachy-
cardia, anosmia, and diarrhea. Laboratory results are: hematocrit 32%
(normal 36.1–44.3%), MCV 102 femtoliters (fL) [(normal 78–98 fL)], 0.3 %
reticulocytes (normal 0.5–2.0%), 95 pg/mL vitamin B12 (normal 200–900
pg/mL), and an abnormal stage I of the Schilling test. Autoantibodies are
detected to a cell type that is found in a region shown in the accompanying
diagram. In which region would those cells be found?
Gastrointestinal Tract and Glands 327a. A
b. B
c. C
d. D
e. E
f. F
g. G
221.A 43-year-old man who recently returned from a trip to rural Peru
presents with severe watery diarrhea, vomiting, and dehydration. He also
has marked leg cramps and has lost 8 lb since his return from the trip. Fecal
culture is positive for V. cholerae. How does this bacterium exert its effect?
a. Activation of enterokinase on the brush border of epithelial cells
b. Activation of cholecystokinin effects on pancreatic secretion
c. Closure of chloride channels in the enterocyte cell membrane
d. Inhibition of cyclic AMP in the enterocytes
e. ADP-ribosylation of GSof the GTP-binding protein in enterocytes