GI physiology: pancreatic enzymes: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · GI physiology: pancreatic enzymes

Sample item

A 3-month-old infant has diarrhoea, failure to thrive and oedema with low serum albumin. Duodenal fluid has normal trypsinogen but no trypsin activity. Which missing enzyme explains this?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Enteropeptidase of the duodenal brush border

Enteropeptidase (enterokinase) converts trypsinogen to trypsin at the duodenal brush border, and trypsin in turn activates the other pancreatic zymogens including chymotrypsinogen and procarboxypeptidase. In its absence, protein digestion fails and protein-losing malabsorption causes hypoalbuminaemia and oedema. Treatment is with pancreatic enzyme supplements.

Option by option

  • A. Enteropeptidase of the duodenal brush border (correct)

    Absent enteropeptidase leaves trypsinogen inactive and prevents activation of the other zymogens.

  • B. Pancreatic lipase

    Lipase deficiency would cause fat malabsorption, with a normal trypsin level.

  • C. Pepsin from gastric chief cells

    Pepsin is not essential for normal protein digestion, since pancreatic proteases are sufficient.

  • D. Salivary amylase

    Salivary amylase has a minor role, and pancreatic amylase compensates for its absence.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, Enteropeptidase of the duodenal brush border. Enteropeptidase (enterokinase) converts trypsinogen to trypsin at the duodenal brush border, and trypsin in turn activates the other pancreatic zymogens including chymotrypsinogen and procarboxypeptidase.

Why is "Pancreatic lipase" not the answer?

Lipase deficiency would cause fat malabsorption, with a normal trypsin level.

Why is "Pepsin from gastric chief cells" not the answer?

Pepsin is not essential for normal protein digestion, since pancreatic proteases are sufficient.

Why is "Salivary amylase" not the answer?

Salivary amylase has a minor role, and pancreatic amylase compensates for its absence.

What concept does this question test?

It tests GI physiology: pancreatic enzymes in Physiology. In its absence, protein digestion fails and protein-losing malabsorption causes hypoalbuminaemia and oedema. Treatment is with pancreatic enzyme supplements.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study GI physiology: pancreatic enzymes?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.