Insulin is secreted by?

Appeared in: AIIMS Delhi NO - 2018

Explanation

Insulin is a hormone synthesized and secreted by the beta (β) cells of the pancreas.
These beta cells are located in the islets of Langerhans, which are clusters of endocrine cells scattered throughout the pancreas.
The primary stimulus for insulin secretion is an increase in blood glucose levels.
Insulin's main function is to lower blood glucose by promoting its uptake and utilization by cells, particularly muscle, liver, and fat cells.

Option B: Alpha-cells of the pancreas secrete glucagon, not insulin. Glucagon has the opposite effect of insulin; it raises blood glucose levels.
Option C: The liver is a major target organ for insulin and is central to glucose metabolism (glycogenesis, glycogenolysis, gluconeogenesis), but it does not produce or secrete insulin.
Option D: The gallbladder is part of the digestive system, responsible for storing and concentrating bile. It has no endocrine function related to glucose homeostasis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Endocrine function of the pancreas and insulin secretion as background academic context rather than a clinical decision trigger.
Understanding that B-cells produce insulin is fundamental to comprehending the pathophysiology of diabetes mellitus. In Type 1 diabetes, these cells are destroyed, leading to an absolute insulin deficiency.
In Type 2 diabetes, B-cells may fail to produce enough insulin to overcome peripheral insulin resistance.
This knowledge is crucial for nurses when educating patients about their condition, explaining the need for insulin therapy, and managing blood glucose levels.

How to Approach the Question

This is a factual recall question testing basic physiology.
First, identify the core subject of the question: the origin of the hormone 'Insulin'.
Recall the major endocrine glands and their functions. The pancreas is the key organ for blood sugar regulation.
Differentiate between the specific cell types within the pancreas. Remember that the islets of Langerhans have different cells with opposing functions.
Associate Beta (B) cells with Insulin (lowers blood sugar) and Alpha (A) cells with Glucagon (raises blood sugar).
Eliminate the other options (Liver, Gallbladder) by recalling their primary functions, which are not related to insulin secretion.

Concept Tested & Keywords

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E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 1099-1101

E6 Physiology Guyton 4SAE Part 3 p. 1

Practise the full AIIMS Delhi NO - 2018

Attempt every question from this paper in a timed mock, then review the full solution for each one.