GI Nutrition, Absorption, and Motility

Question 1

Fat-soluble vitamins (A, D, E, K) are primarily absorbed via which mechanism in the small intestine?

Accepted Answer

Incorporation into micelles and passive diffusion into enterocytes

Answer

Active transport via SGLT1

Answer

Facilitated diffusion via GLUT5

Answer

Pinocytosis via intestinal macrophages

Question 2

Vitamin B12 absorption requires intrinsic factor and is completed in which GI segment?

Accepted Answer

Terminal ileum

Answer

Duodenum

Answer

Proximal jejunum

Answer

Cecum

Question 3

Which electrolyte is primarily absorbed in the colon via aldosterone-regulated sodium channels (ENaC)?

Accepted Answer

Sodium

Answer

Potassium

Answer

Calcium

Answer

Magnesium

Question 4

Short bowel syndrome most commonly causes diarrhea and malabsorption when the remaining small bowel is less than how many centimeters?

Accepted Answer

100 cm

Answer

300 cm

Answer

200 cm

Answer

50 cm

Question 5

Chylomicrons transport dietary lipids from the enterocyte to systemic circulation via which route?

Accepted Answer

Intestinal lacteals → mesenteric lymphatics → thoracic duct → systemic circulation

Answer

Portal vein directly to the liver

Answer

Direct absorption into capillaries and portal vein

Answer

Bile acid recycling via enterohepatic circulation

Question 6

Iron absorption is primarily regulated at which level and is enhanced by which concurrent intake?

Accepted Answer

Intestinal enterocyte uptake; vitamin C (ascorbic acid)

Answer

Renal reabsorption; calcium

Answer

Hepatic storage; vitamin B12

Answer

Bone marrow utilization; vitamin D