A patient takes a medication that nearly eliminates stomach acid production. Which downstream consequence is most directly expected?
AReduced glucose absorption in the duodenum, because acid activates pancreatic amylase
BImpaired protein digestion and increased susceptibility to ingested pathogens
CAccelerated fat emulsification, because bile salts work better at neutral pH
DDecreased bicarbonate secretion by the pancreas, because the stimulus is removed
Stomach acid serves two main roles: it denatures dietary proteins, making them accessible to pepsin, and it kills the majority of ingested microorganisms. Reduced acid therefore impairs early protein processing and removes a major barrier to bacterial/fungal colonization of the small intestine. Pancreatic secretion is actually triggered partly by acid entering the duodenum, so acid suppression can reduce pancreatic stimulation — but that is option D and describes a secondary effect, not the most direct consequence.
Question 2 True / False
The majority of nutrient absorption takes place in the large intestine, which is why it is the longest segment of the GI tract.
TTrue
FFalse
Answer: False
Almost all nutrient absorption — glucose, amino acids, fatty acids, vitamins — occurs in the small intestine, not the large intestine. The large intestine is primarily responsible for reabsorbing water and electrolytes, and it is the site of microbial fermentation of indigestible fiber. The small intestine is in fact the longer segment (~6 m vs ~1.5 m for the large intestine in humans).
Question 3 Short Answer
Explain why fat digestion requires more steps and specialized structures than the digestion of starch or protein.
Think about your answer, then reveal below.
Model answer: Fats are hydrophobic and cannot disperse in the aqueous luminal environment. Bile salts must first emulsify fat globules into smaller droplets (increasing surface area for lipase) before pancreatic lipase can cleave triglycerides into monoglycerides and fatty acids. These products are then packaged into micelles — bile-salt clusters — to be ferried to the brush-border membrane for absorption. Starch and proteins are already polar macromolecules that can interact directly with their enzymes in aqueous solution without prior emulsification.
The extra steps for fat digestion reflect the fundamental incompatibility of nonpolar lipids with a water-based digestive lumen. Each specialized step (bile salt emulsification, lipase hydrolysis, micelle formation) solves a specific aspect of this incompatibility.