Biology · Chemical Coordination and Integration · NEET
The pancreas is a composite gland, meaning it works as both an exocrine gland (releases digestive enzymes) and an endocrine gland. Its endocrine part is the Islets of Langerhans: about 1 to 2 million islets that form only 1-2% of the whole pancreas. Memory hook: "A comes before B" — Alpha-cells make gluc-Agon, Beta-cells make insulin (B for Beta = B for "blood sugar down").
The pancreas is a composite gland: mostly exocrine acini, with Islets of Langerhans (1-2%) as the endocrine part. Beta-cells make insulin (lowers glucose); alpha-cells make glucagon (raises glucose). The two hormones are antagonistic.
Your doubts, answered
Is the pancreas an endocrine or an exocrine gland?
It is both. NCERT calls the pancreas a composite gland because it acts as an exocrine gland (its acini release pancreatic juice with digestive enzymes into the gut) AND as an endocrine gland (the Islets of Langerhans release hormones into the blood). This 'both' point is the most common one-mark trap.
Which cell makes insulin and which makes glucagon?
Beta-cells (β-cells) secrete insulin. Alpha-cells (α-cells) secrete glucagon. Use the hook: Beta = B = brings Blood sugar down (insulin); Alpha = A = gluc-A-gon raises blood sugar. Do not swap them — this exact swap is a repeated NEET trap.
What part of the pancreas is actually endocrine?
Only the Islets of Langerhans are endocrine. There are about 1 to 2 million islets in a normal human pancreas, but they make up only 1 to 2 per cent of the total pancreatic tissue. The other ~98% is exocrine tissue (acini) that helps digestion.
Are insulin and glucagon opposite to each other?
Yes, they are antagonistic. Insulin lowers blood glucose (hypoglycemic hormone) and glucagon raises blood glucose (hyperglycemic hormone). Both are peptide hormones made in the same islets but by different cells, so together they keep blood glucose steady (homeostasis).
What are the other minor cell types in the islets?
For NEET, the two main cells you must know are alpha (glucagon) and beta (insulin). Delta-cells (secreting somatostatin) exist but NCERT names only alpha and beta as the 'two main types,' so answer alpha and beta unless the question specifically asks beyond NCERT.
⚠️ The NEET trap ✗ Alpha-cells secrete insulin and beta-cells secrete glucagon. ✓ Alpha-cells secrete glucagon; beta-cells secrete insulin. The pancreas is a composite gland and the islets are only 1-2% of its tissue. 🧠 NTA loves the alpha/beta swap. Lock it: Beta = insulin (both have the sound 'in'... Beta-cell → insulin). Alpha → glucagon.
Real NEET questions
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, alpha-cells secrete glucagon and beta-cells secrete insulin. So the statement 'alpha-cells secrete insulin' is incorrect. The other three are correct: alpha make glucagon, glucagon triggers glycogenolysis (glycogen to glucose, raising blood sugar), and beta make insulin.
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: Insulin and glucagon ARE antagonistic (insulin lowers, glucagon raises blood glucose) — so that pair is not the answer. Parathormone-Calcitonin and Aldosterone-ANF are also antagonistic. Relaxin and Inhibin act on different reproductive processes and are not opposite, so they are the non-antagonistic pair.
Solved Chemical Coordination and Integration NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Why is the pancreas called a composite or heterocrine gland?
Because one organ does two jobs: the exocrine part (acini) makes digestive enzymes sent to the intestine through a duct, and the endocrine part (Islets of Langerhans) makes hormones released straight into the blood.
How many Islets of Langerhans are in the human pancreas?
About 1 to 2 million islets, but they form only 1 to 2 per cent of the total pancreatic tissue (NCERT).
Are insulin and glucagon steroid or peptide hormones?
Both are peptide (protein) hormones. This is why insulin cannot be given as a pill — it would be digested in the gut. This point is directly tested by NEET.
What is the difference between alpha and beta cells?
Alpha-cells secrete glucagon (raises blood glucose); beta-cells secrete insulin (lowers blood glucose). They sit together in the same islet but do opposite jobs.
Which is the most important line to remember for NEET?
Pancreas is a composite gland; endocrine part = Islets of Langerhans (1-2% of tissue); alpha-cells = glucagon, beta-cells = insulin; the two hormones are antagonistic.
