A rise in blood sugar (glucose) level is detected by the endocrine cells of which organ, which then secrete insulin?

Introduction / Context:
Regulation of blood sugar is a key concept in human physiology and is closely connected to understanding diabetes and endocrine control. When blood glucose levels rise after a meal, the body must detect this change and respond by releasing hormones that lower the sugar level. This question asks you to identify which organ contains the endocrine cells that sense higher blood sugar and secrete insulin as a regulatory response. Recognising the correct organ is essential for basic biology and health science questions.

Given Data / Assumptions:
– The situation described is a rise in blood sugar levels in the body.
– The organ sought is the one whose cells detect this change and release insulin.
– Options are Liver, Gall bladder, Kidney, and Pancreas.
– We assume standard physiological knowledge where insulin is the main hormone that lowers blood glucose.

Concept / Approach:
The hormone insulin is produced by beta cells in the islets of Langerhans, which are clusters of endocrine cells in the pancreas. When blood glucose rises after eating, these beta cells detect the increase and secrete insulin into the bloodstream. Insulin then promotes uptake of glucose by tissues and stimulates the liver and muscles to store glucose as glycogen, thereby lowering the blood sugar level. The liver plays a major role in storing and releasing glucose but does not secrete insulin. The gall bladder stores bile for fat digestion, and the kidneys filter blood to form urine; neither of these organs produces insulin. Therefore, the pancreas is the organ that directly detects higher blood sugar through its endocrine cells and responds by releasing insulin.

Step-by-Step Solution:
Step 1: Recall that insulin is the hormone that lowers blood glucose levels after a meal. Step 2: Remember that insulin is produced by beta cells located in the islets of Langerhans within the pancreas. Step 3: Understand that these beta cells act as sensors for blood glucose and respond to rising levels by increasing insulin secretion. Step 4: Recognise that liver, gall bladder, and kidney have important functions but are not the primary source of insulin. Step 5: Conclude that the pancreas is the organ whose cells detect a rise in blood sugar and secrete insulin.

Verification / Alternative check:
Physiology textbooks and medical references clearly state that insulin is secreted by beta cells of the islets of Langerhans in the pancreas. Diagrams of the endocrine pancreas show different cell types: alpha cells that secrete glucagon, beta cells that secrete insulin, and delta cells that produce somatostatin. Discussions about diabetes mellitus emphasise pancreatic dysfunction, particularly damage to or failure of beta cells. This strong and consistent association between insulin and the pancreas confirms that it is the correct organ in this question.

Why Other Options Are Wrong:
Liver: The liver stores glucose as glycogen and releases it when needed, but it does not produce insulin; it responds to insulin rather than secreting it.
Gall bladder: This organ stores and concentrates bile produced by the liver and releases it into the intestine for fat digestion; it has no role in insulin secretion or direct detection of blood sugar levels.
Kidney: Kidneys filter blood to remove wastes and regulate fluid and electrolyte balance; although they handle glucose reabsorption, they are not the primary endocrine organ for insulin production.

Common Pitfalls:
Students sometimes confuse the liver and pancreas because both are located in the abdominal region and are involved in digestion and metabolism. They may incorrectly think that the liver produces insulin because it plays such a big role in glucose storage. To avoid this confusion, remember that the pancreas has dual roles: exocrine (digestive enzymes) and endocrine (hormones like insulin and glucagon). The liver cooperates with these hormones but does not produce them. Keeping this division of labour in mind helps answer related questions accurately.

Final Answer:
A rise in blood sugar is detected by endocrine cells in the Pancreas, which then secrete insulin to help lower the glucose level.