Endocrine pancreas: glucagon signalling: 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.

Try it

Physiology · Endocrine pancreas: glucagon signalling

Sample item

A 55-year-old woman with a pancreatic alpha cell tumour has hyperglycaemia and weight loss. Which second messenger pathway mediates the action of the excess hormone on hepatocytes?

AGq protein activation of phospholipase C, producing IP3 and DAGBNitric oxide activation of guanylyl cyclase and cGMPCGs protein activation of adenylyl cyclase, raising cAMP and activating protein kinase ADReceptor tyrosine kinase activation of PI3 kinase

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

The answer and the reasoning

C. Gs protein activation of adenylyl cyclase, raising cAMP and activating protein kinase A

Glucagon binds a Gs-coupled receptor on hepatocytes, increasing cAMP and protein kinase A, which activates phosphorylase kinase and glycogenolysis and induces gluconeogenic enzymes such as PEPCK. The result is raised hepatic glucose output. Insulin acts through a tyrosine kinase receptor and has opposing effects.

Option by option

A. Gq protein activation of phospholipase C, producing IP3 and DAG
The Gq-IP3 pathway is used by alpha-1 receptors, not the glucagon receptor.
B. Nitric oxide activation of guanylyl cyclase and cGMP
cGMP via nitric oxide mediates vasodilatation and does not mediate glucagon action.
C. Gs protein activation of adenylyl cyclase, raising cAMP and activating protein kinase A (correct)
Correct. The cAMP-PKA pathway drives glycogenolysis and gluconeogenesis.
D. Receptor tyrosine kinase activation of PI3 kinase
The PI3 kinase pathway is the insulin pathway.

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.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is C, Gs protein activation of adenylyl cyclase, raising cAMP and activating protein kinase A. Glucagon binds a Gs-coupled receptor on hepatocytes, increasing cAMP and protein kinase A, which activates phosphorylase kinase and glycogenolysis and induces gluconeogenic enzymes such as PEPCK.

Why is "Gq protein activation of phospholipase C, producing IP3 and DAG" not the answer?

The Gq-IP3 pathway is used by alpha-1 receptors, not the glucagon receptor.

Why is "Nitric oxide activation of guanylyl cyclase and cGMP" not the answer?

cGMP via nitric oxide mediates vasodilatation and does not mediate glucagon action.

Why is "Receptor tyrosine kinase activation of PI3 kinase" not the answer?

The PI3 kinase pathway is the insulin pathway.

What concept does this question test?

It tests Endocrine pancreas: glucagon signalling in Physiology. The result is raised hepatic glucose output. Insulin acts through a tyrosine kinase receptor and has opposing effects.

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 Endocrine pancreas: glucagon signalling?

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.