Biology · Chemical Coordination and Integration · NEET
Insulin and glucagon are antagonistic hormones from the pancreas. Insulin (from β-cells) LOWERS blood glucose, while glucagon (from α-cells) RAISES it. Together they keep blood sugar steady, like a thermostat with a cooler and a heater. Memory hook: "B for β and Below" (insulin from β-cells brings glucose below/down); glucagon "guns up" the glucose.
Insulin (β-cells) pulls blood glucose down by uptake and glycogenesis; glucagon (α-cells) pushes it up by glycogenolysis and gluconeogenesis. Their opposite pull keeps blood sugar steady.
Your doubts, answered
Why are insulin and glucagon called antagonistic hormones?
They act on the same thing (blood glucose) but push it in opposite directions. Insulin lowers blood glucose, glucagon raises it. Because their effects oppose each other, they are called antagonistic. NCERT lists Insulin-Glucagon as a classic antagonistic pair, just like PTH-Calcitonin.
Which cells make insulin and which make glucagon?
Both come from the Islets of Langerhans in the pancreas. The β-cells (beta) secrete INSULIN. The α-cells (alpha) secrete GLUCAGON. A very common NEET trap is to swap these. Remember: β for insulin, α for glucagon.
How does insulin actually lower blood glucose?
Insulin acts mainly on hepatocytes (liver cells) and adipocytes (fat cells). It increases glucose uptake into cells and promotes glycogenesis (glucose stored as glycogen). Less glucose stays in the blood, so blood sugar falls. So insulin is a hypoglycemic hormone.
How does glucagon raise blood glucose?
Glucagon acts mainly on liver cells. It stimulates glycogenolysis (glycogen broken down into glucose) and gluconeogenesis (new glucose made from non-carbohydrates). Glucose is released into the blood, so blood sugar rises. So glucagon is a hyperglycemic hormone.
What is the difference between glycogenolysis and glycogenesis?
Glycogenesis = making glycogen FROM glucose (storing sugar; done under insulin). Glycogenolysis = breaking glycogen INTO glucose (releasing sugar; done under glucagon). One letter difference, opposite meaning. NEET loves testing this pair.
Are insulin and glucagon steroid or peptide hormones?
Both are PEPTIDE (protein) hormones, not steroids. This is why insulin cannot be given as a tablet (it would be digested) and must be injected. NEET 2024 asked which is NOT a steroid, and glucagon was the answer.
⚠️ The NEET trap ✗ α-cells secrete insulin and β-cells secrete glucagon. ✓ β-cells secrete INSULIN; α-cells secrete GLUCAGON. 🧠 NEET repeatedly gives the reversed pairing as a wrong option. Lock it: Beta = insulin (Below/lowers glucose), Alpha = glucagon (Adds glucose).
Real NEET questions
2016
Which of the following pairs of hormones are not antagonistic (having opposite effects) to each other?
A · Parathormone - Calcitonin
B · Insulin - Glucagon
C · Aldosterone - Atrial Natriuretic Factor
D · Relaxin - Inhibin ✓
Solution: Antagonistic pairs push a variable in opposite directions: Parathormone raises blood Ca²⁺ while Calcitonin lowers it; Insulin lowers blood glucose while Glucagon raises it; Aldosterone raises blood pressure while ANF lowers it. Relaxin (relaxes pelvic ligaments at birth) and Inhibin (inhibits FSH) act on unrelated targets, so they are NOT antagonistic. This confirms Insulin-Glucagon IS a true antagonistic pair.
2018
Which one of the following statements is incorrect?
A · α-cells of pancreas secrete glucagon
B · α-cells of pancreas secrete insulin ✓
C · Glucagon stimulates glycogenolysis
D · β-cells of pancreas secrete insulin
Solution: In the Islets of Langerhans, α-cells secrete glucagon and β-cells secrete insulin. Glucagon stimulates glycogenolysis, raising blood glucose. The incorrect statement is that α-cells secrete insulin; they secrete glucagon. (Repeated in ReNEET 2026.)
NEET
Select the correct statement.
A · Insulin acts on pancreatic cells and adipocytes
B · Insulin is associated with hyperglycemia
C · Glucocorticoids stimulate gluconeogenesis ✓
D · Glucagon is associated with hypoglycemia
Solution: Glucocorticoids (cortisol) stimulate gluconeogenesis, so (C) is correct. Insulin acts on hepatocytes and adipocytes (not pancreatic cells) and is hypoglycemic, so (A) and (B) are wrong. Glucagon is hyperglycemic (raises glucose), so (D) is wrong. This tests that insulin lowers and glucagon raises blood glucose.
Solved Chemical Coordination and Integration NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
