Concept understanding — Pancreas Insulin And Glucagon
The pancreas is a long, pale organ tucked behind your stomach. Most people know it for making digestive juices, but scattered through it like tiny islands are clusters of cells called the Islets of Langerhans. These islands are the body's blood-sugar control room.
Think of your blood glucose as the fuel level in a car. Too low, and the engine sputters (you feel dizzy, weak). Too high, and you're wasting fuel and damaging the engine over time. The body needs to keep that fuel gauge right in the middle. The Islets of Langerhans do this with two hormones that work like a gas pedal and a brake.
Insulin is the brake. When you eat a meal, blood glucose rises. The beta cells of the islets sense this rise and release insulin. Insulin tells every cell in your body: "Open up, take glucose out of the blood, use it for energy or store it as glycogen in the liver and muscles." The result? Blood glucose falls back to normal.
Glucagon is the gas pedal. When you haven't eaten for a while, blood glucose starts to drop. The alpha cells of the islets sense this and release glucagon. Glucagon tells the liver: "Break down your stored glycogen and release glucose into the blood." The result? Blood glucose rises back to normal.
These two hormones are antagonists — they pull in opposite directions. Insulin lowers blood glucose; glucagon raises it. Together, they form a perfect feedback loop that keeps your blood sugar stable whether you just ate a feast or skipped breakfast.
High blood glucosestimulatesβ-cells→Insulin→Glucose uptake→Blood glucose ↓
Insulin, secreted by the beta cells of the islets of Langerhans, is a hypoglycaemic hormone. It lowers blood glucose by promoting the cellular uptake of glucose and its conversion into glycogen in the liver and muscles — a process called glycogenesis. It also promotes conversion of glucose to fat. Glycogenolysis (glycogen → glucose) and gluconeogenesis (glucose from non-c …
Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.
CBSE 2026Set ANNUAL1 markMCQ
Q.Assertion (A): Insulin lowers blood glucose level after meal.
Reason (R): Insulin stimulates the conversion of glucose into glycogen in liver and muscles.
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not correct explanation of Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.
›Reveal solutionSolution
Insulin, secreted by the beta cells of the pancreatic islets of Langerhans in response to rising blood glucose after a meal, lowers blood glucose precisely by stimulating liver and muscle cells to convert glucose into glycogen (glycogenesis) for storage — so A is true and R is its correct mechanistic explanation.
After a meal, blood glucose rises as carbohydrates are digested and absorbed. This rise directly stimulates the pancreas to secrete insulin. Insulin then acts on target cells (mainly liver and muscle) in several coordinated ways: it increases glucose uptake into cells (via GLUT4 transporters, especially in muscle and adipose tissue), and — most relevant here — it activates the enzyme glycogen synthase, driving the conversion of free glucose into glycogen, the storage polysaccharide, in liver and muscle cells. By pulling glucose out of the bloodstre …
Glucagon, the hyperglycaemic hormone, is secreted by the alpha cells of the pancreatic islets of Langerhans.
The pancreas is a heterocrine gland: its exocrine part secretes digestive enzymes, while its endocrine part consists of clusters of cells called the islets of Langerhans. These islets contain:
Alpha (α) cells — secrete glucagon, which raises blood glucose level by stimulating glycogenolysis (breakdown of liver glycogen to glucose) and gluconeogenesis.
Beta (β) cells — secrete insulin, which lowers blood glucose by promoting glucose uptake and glycogen synthesis.
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β cells of the pancreatic islets secrete insulin; α cells secrete glucagon.
The pancreas has an endocrine portion made up of clusters of cells called the islets of Langerhans, which contain two major cell types:
α (alpha) cells, which secrete glucagon, a hormone that raises blood glucose levels (by promoting glycogen breakdown and glucose release from the liver). …