BiologyICSE Class 10 · Endocrine System

The Pancreas: Insulin, Glucagon and Blood Glucose Control (ICSE Class 10 Biology)

Updated 16 October 2026 · Fact-checked

The pancreas is a mixed gland lying in the loop of the duodenum. Its exocrine part makes pancreatic juice; its endocrine islets of Langerhans make insulin (beta cells), which lowers blood glucose by storing it as glycogen, and glucagon (alpha cells), which raises it. Lack of insulin causes diabetes mellitus.

Insulin and glucagon work in opposite directions, so blood glucose is pulled back to the normal level from either side.

Illustration drawn for QuestionBuddy.

Understand Pancreas: Insulin and Glucagon

Location and shape. The pancreas is an elongated, leaf-like gland lying behind the stomach, in the loop of the duodenum.

A mixed (heterocrine) gland.

Part	Type	Product	Route
Acini (most of the gland)	exocrine	pancreatic juice (digestive enzymes)	pancreatic duct → duodenum
Islets of Langerhans (scattered clusters)	endocrine	insulin, glucagon	directly into blood

Insulin (from beta cells) lowers blood glucose.

Helps body cells take up glucose from the blood.
Makes the liver and muscles convert glucose into glycogen for storage.
Secreted when blood glucose rises, for example after a meal.

Glucagon (from alpha cells) raises blood glucose.

Converts liver glycogen back into glucose.
Secreted when blood glucose falls, for example during fasting.

Working as a pair. Insulin and glucagon act in opposite directions, keeping blood glucose within a narrow normal range, much as two people on a see-saw keep it level.

Disorders.

Condition	Cause	Features
Diabetes mellitus	hyposecretion of insulin (or cells not responding to it)	high blood glucose; glucose in urine; frequent urination; great thirst; tiredness; slow healing
Hypoglycaemia	hypersecretion of insulin (or an insulin overdose)	very low blood glucose; weakness, sweating, fainting

Why sugar appears in urine. When blood glucose is very high, the kidney filters more glucose than the tubules can reabsorb, so some is left in the urine. The extra glucose carries water with it, causing frequent urination and thirst.

Diabetes mellitus versus diabetes insipidus.

Point	Mellitus	Insipidus
Gland	pancreas	pituitary
Hormone lacking	insulin	ADH
Urine	sugar present	large volume, dilute, no sugar

Treatment idea. Insulin is a protein, so it is digested if swallowed; diabetic patients take it by injection, along with controlled diet and exercise.

Flow chart: glucose balance. Meal → blood glucose rises → beta cells → insulin → glucose to glycogen, cells take up glucose → glucose falls to normal. Fasting → glucose falls → alpha cells → glucagon → glycogen to glucose → glucose rises to normal.

Draw-and-label checklist: position. Stomach, C-shaped duodenum, and the pancreas lying in the loop with its duct opening into the duodenum; an inset showing an islet of Langerhans among acini, labelled alpha cells and beta cells.

Pancreas: Insulin and Glucagon: key facts

Pancreas as a mixed gland: Exocrine: pancreatic juice through a duct to the duodenum | Endocrine: islets of Langerhans, hormones into blood; Called a heterocrine gland.
Insulin and glucagon: Insulin (beta cells): glucose to glycogen, lowers blood glucose | Glucagon (alpha cells): glycogen to glucose, raises blood glucose; Opposite actions keep glucose steady.
Disorders: Insulin low: diabetes mellitus, sugar in urine | Insulin high: hypoglycaemia; Mellitus = pancreas; insipidus = pituitary.

How to answer Pancreas: Insulin and Glucagon questions

ICSE asks you to explain why the pancreas is a mixed gland, name the hormone and cells for a glucose change, describe diabetes mellitus, and distinguish it from diabetes insipidus by gland.

1For 'mixed gland', give both parts with their products and routes.
2Glucose too high → insulin; too low → glucagon.
3Name the cells: beta for insulin, alpha for glucagon.
4For diabetes, give hormone, gland, and two symptoms.
5When asked for the gland, write the gland, not the hormone.

Pancreas: Insulin and Glucagon in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Sweets after dinner

Suppose after a wedding feast with several sweets, a healthy person's blood glucose rises sharply but is back to normal within about two hours.

Explain how the body brings it back.

Try it first, then show the solutionSolution

The rise in blood glucose is sensed by beta cells of the islets of Langerhans.
They secrete insulin into the blood.
Insulin helps cells take up glucose and makes the liver and muscles store it as glycogen.
Blood glucose falls back to normal and insulin secretion slows.

Answer: Insulin from beta cells moves glucose into cells and stores it as glycogen.

Memory hook: Insulin puts sugar IN storage.

Skipping breakfast

Suppose a student skips breakfast and has a long morning of classes but does not faint.

Which hormone keeps her blood glucose up, and how?

Try it first, then show the solutionSolution

As blood glucose falls, alpha cells of the islets secrete glucagon.
Glucagon makes the liver convert stored glycogen into glucose.
Glucose is released into the blood.
Blood glucose stays near normal until she eats.

Answer: Glucagon from alpha cells releases glucose from liver glycogen.

Memory hook: Glucagon = glucose gone? Get it back.

Tricks to remember Pancreas: Insulin and Glucagon

Short memory aids. Say each one aloud once, then use it on a question the same day.

Beta Brings it down
Beta cells make insulin, which Brings glucose down; Alpha cells Add glucose.
Use it when: Matching cells to hormones.
Mellitus = honey
Mellitus means honey-sweet: sugar in urine. Insipidus means tasteless: dilute urine.
Use it when: Two diabetes.
Islets in an ocean
Islets of Langerhans are tiny islands of endocrine cells in an ocean of exocrine acini.
Use it when: Mixed gland.

Pancreas: Insulin and Glucagon: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Hormone that lowers glucose · 1 mark · MCQBoard level

The hormone that lowers blood glucose by converting it to glycogen is:
(a) glucagon (b) insulin (c) adrenaline (d) thyroxine

Try it first, then show the solutionSolution

Insulin lowers blood glucose.

Answer: (b) insulin.

Example 2: Mixed gland · 2 marks · Short answerBoard level

Why is the pancreas called a mixed gland?

Try it first, then show the solutionSolution

Its exocrine part secretes pancreatic juice through a duct into the duodenum (1 mark).
Its endocrine part, the islets of Langerhans, secretes insulin and glucagon directly into the blood (1 mark).

Answer: It has an exocrine part (pancreatic juice by duct) and an endocrine part (hormones into blood).

Example 3: Insulin versus glucagon · 3 marks · Short answerHarder board level

Give three differences between insulin and glucagon.

Try it first, then show the solutionSolution

Cells: insulin from beta cells; glucagon from alpha cells (1 mark).
Action: insulin converts glucose to glycogen; glucagon converts glycogen to glucose (1 mark).
Effect: insulin lowers blood glucose; glucagon raises it (1 mark).

Answer: Beta versus alpha cells; glucose → glycogen versus glycogen → glucose; lowers versus raises glucose.

Example 4: Insulin present, glucose still high · 2 marks · Short answerHarder board level

A patient's blood glucose stays high for hours after meals, yet tests show that her pancreas releases normal amounts of insulin. (a) Suggest why her glucose stays high. (b) Name the disorder and one sign that would appear in her urine.

Try it first, then show the solutionSolution

(a) Her body cells do not respond properly to insulin, so glucose is not taken up from the blood or stored as glycogen (1 mark).
(b) Diabetes mellitus; glucose in the urine (1 mark).

Answer: (a) Cells do not respond to insulin. (b) Diabetes mellitus; glucose in urine.

Example 5: Glucose readings · 3 marks · Case-basedHOTS / competency

Suppose a healthy student's fasting blood glucose is 90 mg/dL and an hour after lunch it is 160 mg/dL. (a) By how much and by what percentage did it rise? (b) Which hormone brings it back down? (c) In a diabetic person, why would the reading stay high much longer?

Try it first, then show the solutionSolution

(a) 160 − 90 = 70 mg/dL; 70 ÷ 90 × 100 ≈ 77.8% (1 mark).
(b) Insulin (1 mark).
(c) Too little insulin (or cells not responding) means glucose is not taken up or stored, so it stays high (1 mark).

Answer: (a) 70 mg/dL, about 77.8%. (b) Insulin. (c) Insulin lacking or ineffective.

Example 6: Why injections? · 3 marks · Short answerHOTS / competency

Suppose a diabetic child asks why she cannot simply swallow insulin tablets. Explain, and state what may happen if she injects too much insulin and skips a meal.

Try it first, then show the solutionSolution

Insulin is a protein, so digestive enzymes in the stomach and intestine would break it down before it reaches the blood (1 mark).
Injection puts it directly into the blood (1 mark).
Too much insulin with no food can make blood glucose fall too low (hypoglycaemia), causing weakness, sweating or fainting (1 mark).

Answer: Swallowed insulin is digested; injection avoids this. Overdose with no meal causes hypoglycaemia.

Where students lose marks in Pancreas: Insulin and Glucagon

The slips examiners see most often, and what to write instead.

Mistake: Hormone named instead of gland
CISCE examiners' comments (2024): distinguishing diabetes mellitus and insipidus by the gland concerned, candidates wrote names of hormones instead of glands.
Do this: Mellitus: pancreas; insipidus: pituitary.
Usually costs: 1-2 marks.
Mistake: Glands and hormones not correlated
CISCE examiners' comments (2025): in a gland-function matching item, candidates could not correlate endocrine glands with the hormones they produce.
Do this: Pancreas → insulin and glucagon; learn each gland's hormones as a set.
Usually costs: 1 mark each.
Mistake: Insulin and glucagon swapped
The two names sound similar; reversing them inverts every answer on glucose control.
Do this: Insulin: in to storage, lowers; glucagon: glucose gone, raises.
Usually costs: 1 mark.

Exam tips

Pancreas: mixed gland, in the loop of the duodenum.
Beta cells: insulin, lowers glucose; alpha cells: glucagon, raises glucose.
Low insulin: diabetes mellitus, sugar in urine.
Give the gland when the gland is asked.

Practice questions on Pancreas: Insulin and Glucagon

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
Glucagon is secreted by the:
(a) beta cells (b) alpha cells (c) acini (d) adrenal medulla
Hint
Alpha adds.
Answer
(b) alpha cells.
Q2 · 1 mark · Very short answerBoard level
Name the endocrine tissue of the pancreas.
Hint
Islands.
Answer
Islets of Langerhans.
Q3 · 1 mark · Assertion-reasonHarder board level
Assertion (A): A person with untreated diabetes mellitus often feels very thirsty.
Reason (R): Glucose left in the kidney filtrate carries extra water with it into the urine.
(a) (A) is true and (R) is false.
(b) (A) is false and (R) is true.
(c) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(d) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
Hint
Where does the lost water come from?
Answer
(c).
Q4 · 2 marks · Short answerHarder board level
State the location and shape of the pancreas.
Hint
Behind the stomach.
Answer
An elongated, leaf-like gland behind the stomach, lying in the loop of the duodenum.
Q5 · 2 marks · Short answerHarder board level
Both diabetes mellitus and diabetes insipidus cause frequent urination. Explain the different reason for the large urine volume in each.
Hint
Glucose drags water; ADH saves water.
Answer
Mellitus: lack of insulin leaves so much glucose in the filtrate that it cannot all be reabsorbed, and it carries water with it into the urine. Insipidus: lack of ADH from the pituitary means less water is reabsorbed in the distal tubule and collecting duct, so much dilute urine is passed.
Q6 · 2 marks · Short answerHarder board level
What is hypoglycaemia? State one cause.
Hint
Too low.
Answer
An abnormally low blood glucose level; caused by excess insulin (hypersecretion or overdose).
Q7 · 2 marks · Short answerHarder board level
Name the storage form of glucose made under the action of insulin and two organs where it is stored.
Hint
Animal starch.
Answer
Glycogen; stored in the liver and muscles.
Q8 · 3 marks · Case-basedHOTS / competency
Read and answer.
Suppose in an experiment the pancreatic duct of an animal is tied, so pancreatic juice cannot reach the duodenum, but blood glucose stays normal.
(a) Which function of the pancreas is affected? (1)
(b) Why does blood glucose stay normal? (1)
(c) What does this show about the pancreas? (1)
Hint
Duct versus blood.
Answer
(a) Exocrine function (digestion by pancreatic juice). (b) Insulin and glucagon go directly into the blood, not through the duct. (c) It has separate exocrine and endocrine parts: a mixed gland.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Which cells secrete insulin?Show answer
Beta cells of the islets of Langerhans.
2.What does glucagon do?Show answer
Converts liver glycogen to glucose, raising blood glucose.
3.What is the main sign of diabetes mellitus in urine?Show answer
Presence of glucose.
4.Where does pancreatic juice go?Show answer
Into the duodenum through the pancreatic duct.
5.Why is insulin injected?Show answer
It is a protein and would be digested if swallowed.

Pancreas: Insulin and Glucagon: frequently asked questions

Do I need Type 1 and Type 2 diabetes?

Not by name. Know that diabetes mellitus is due to lack of insulin or its failure to act.

Is the pancreas the only mixed gland?

The gonads also have both functions, but ICSE uses the pancreas as the standard example.

Does adrenaline also affect blood glucose?

Yes. It raises blood glucose in emergencies, like glucagon.

What is glycogen?

The storage carbohydrate of animals, made from glucose in the liver and muscles.