🧬 Endocrine Glands – Full Breakdown
ICSE Class 10
Biology
June 2026
The endocrine system is the body's chemical messenger network. While the nervous system sends fast electrical signals, the endocrine system sends slower but longer-lasting chemical signals (hormones) through the blood. This chapter is all about which gland produces which hormone, what that hormone does, and what happens when it's too much or too little. ICSE loves table-based questions matching glands to hormones to disorders. Written by someone who scored 93.4% in ICSE 2026.
1) The Endocrine System — An Overview
Endocrine System: A system of ductless glands that secrete hormones directly into the bloodstream to regulate various body functions including growth, metabolism, reproduction, and homeostasis.
Endocrine vs Exocrine Glands
| Feature | Endocrine Glands | Exocrine Glands |
|---|---|---|
| Ducts | No ducts — secrete hormones directly into blood | Have ducts — secrete through tubes to a surface or cavity |
| Secretion | Hormones (chemical messengers) | Enzymes, sweat, mucus, saliva, sebum, milk |
| Target | Distant organs via bloodstream | Local — near the site of secretion |
| Speed | Slow but long-lasting effects | Fast, short-lived effects |
| Examples | Pituitary, thyroid, adrenal, pancreas (islets) | Salivary glands, sweat glands, liver (bile), pancreas (digestive enzymes) |
⚠️ The pancreas is BOTH an exocrine and endocrine gland:
Exocrine part: Acinar cells secrete digestive enzymes (amylase, lipase, trypsin) through ducts into the duodenum.
Endocrine part: Islets of Langerhans (alpha & beta cells) secrete insulin & glucagon directly into blood.
This dual nature is a very common board question — "Why is the pancreas called a mixed gland?"
Exocrine part: Acinar cells secrete digestive enzymes (amylase, lipase, trypsin) through ducts into the duodenum.
Endocrine part: Islets of Langerhans (alpha & beta cells) secrete insulin & glucagon directly into blood.
This dual nature is a very common board question — "Why is the pancreas called a mixed gland?"
Hormones — The Chemical Messengers
Hormones: Chemical substances produced by endocrine glands, secreted directly into blood, which travel to target organs and regulate specific physiological processes (growth, metabolism, reproduction, mood, etc.).
Properties of hormones:
- Produced in small amounts but have powerful effects
- Travel via bloodstream to distant target organs
- Act only on target cells that have specific receptors
- Are destroyed after use (by liver & kidneys) — they don't accumulate
- Work with the nervous system to maintain homeostasis
2) Major Endocrine Glands — Location & Quick Reference
| Gland | Location | Major Hormones | Category |
|---|---|---|---|
| Hypothalamus | Brain (above pituitary) | Releasing/inhibiting hormones (TRH, CRH, GnRH, etc.), ADH & oxytocin (synthesised here, stored in posterior pituitary) | Neuroendocrine |
| Pituitary | Base of brain (sella turcica of sphenoid bone) | GH, TSH, ACTH, FSH, LH, PRL, MSH (anterior); ADH, oxytocin (posterior) | "Master Gland" |
| Thyroid | Neck (below larynx, over trachea) | T₃ (triiodothyronine), T₄ (thyroxine), Calcitonin | Metabolic regulator |
| Parathyroid | Embedded in thyroid (4 small glands) | PTH (Parathormone) | Calcium regulator |
| Adrenal Cortex | On top of each kidney (outer part) | Aldosterone, Cortisol, Androgens (DHEA) | Stress & salt balance |
| Adrenal Medulla | Inside adrenal (inner part) | Adrenaline (epinephrine), Noradrenaline (norepinephrine) | "Fight or flight" |
| Pancreas (Islets) | Abdomen (behind stomach) | Insulin (β cells), Glucagon (α cells) | Blood glucose regulation |
| Testes (♂) | Scrotum | Testosterone | Male sex hormone |
| Ovaries (♀) | Pelvis | Oestrogen, Progesterone | Female sex hormones |
| Thymus | Upper chest (behind sternum) | Thymosin, Thymopoietin | Immune system (T-cell maturation) |
| Pineal | Brain (between cerebral hemispheres) | Melatonin | Circadian rhythm / sleep-wake cycle |
3) Hypothalamus — The Master Controller
The hypothalamus is a small region at the base of the brain that connects the nervous system to the endocrine system. It's the real master — it controls the pituitary gland.
- Produces releasing hormones: TRH (→ TSH), CRH (→ ACTH), GnRH (→ FSH, LH), GHRH (→ GH), somatostatin (inhibits GH)
- Synthesises ADH & Oxytocin — stored in posterior pituitary and released when needed
- Thermoregulation: Body temperature control (sweating, shivering)
- Osmoregulation: Detects blood concentration → triggers thirst & ADH release
- Appetite, sleep, emotional responses
💡 Think of it this way: The hypothalamus is the CEO who gives orders (releasing hormones). The pituitary is the manager who delegates to other glands (by secreting tropic hormones). The other glands are the workers who execute the job (secreting final hormones like T₄, cortisol, sex hormones).
4) Pituitary Gland — The Master Gland
Pea-sized gland (~0.5 g) at the base of the brain, housed in the sella turcica of the sphenoid bone. Connected to the hypothalamus by the pituitary stalk. Divided into anterior (adenohypophysis) and posterior (neurohypophysis) lobes.
Anterior Pituitary Hormones
| Hormone | Full Name | Target | Action |
|---|---|---|---|
| GH | Growth Hormone (Somatotropin) | All cells (bones, muscles, organs) | Stimulates growth — protein synthesis, cell division, bone elongation |
| TSH | Thyroid Stimulating Hormone | Thyroid gland | Stimulates thyroid to produce T₃ & T₄ |
| ACTH | Adrenocorticotropic Hormone | Adrenal cortex | Stimulates release of cortisol & aldosterone |
| FSH | Follicle Stimulating Hormone | Gonads | ♀: Egg follicle development. ♂: Sperm production (spermatogenesis) |
| LH | Luteinising Hormone | Gonads | ♀: Ovulation + progesterone production. ♂: Testosterone production (interstitial cells) |
| PRL | Prolactin | Mammary glands | Milk production (lactation) after childbirth |
| MSH | Melanocyte Stimulating Hormone | Melanocytes (skin) | Stimulates melanin synthesis → skin darkening |
Posterior Pituitary Hormones
(Actually synthesised by the hypothalamus, stored & released by posterior pituitary)
| Hormone | Target | Action |
|---|---|---|
| ADH (Vasopressin) | Kidney (DCT & collecting duct) | Increases water reabsorption → reduces urine volume (cover |
| Oxytocin | Uterus & Mammary glands | Stimulates uterine contractions (childbirth) & milk ejection (let-down reflex) |
Disorders of Pituitary Gland
Growth Hormone Disorders:
- Hyposecretion (childhood): Dwarfism — stunted growth, normal intelligence (proportionate short stature). GH treatment available.
- Hypersecretion (childhood): Gigantism — excessive growth (up to 8+ feet). Bones grow proportionally.
- Hypersecretion (adulthood): Acromegaly — bones of hands, feet, and face enlarge disproportionately (jaw protrudes, fingers thicken). Caused by pituitary tumour.
ADH Disorders:
- Hyposecretion: Diabetes Insipidus — inability to concentrate urine → excessive urination (polyuria up to 20 L/day) + excessive thirst (polydipsia). Not related to blood sugar!
- Hypersecretion: SIADH (Syndrome of Inappropriate ADH) — too much water retention → diluted blood (hyponatraemia).
⚠️ Dwarfism vs Cretinism — DO NOT CONFUSE:
Pituitary dwarfism: GH deficiency → proportionate short stature, normal intelligence.
Thyroid cretinism: T₄ deficiency in childhood → stunted growth + severe mental retardation.
This distinction is a guaranteed board question — they will ask "A child is short in stature with normal intelligence. Which hormone deficiency?" Answer: Growth Hormone (dwarfism). If mental retardation is added, it's thyroid hormone (cretinism).
Pituitary dwarfism: GH deficiency → proportionate short stature, normal intelligence.
Thyroid cretinism: T₄ deficiency in childhood → stunted growth + severe mental retardation.
This distinction is a guaranteed board question — they will ask "A child is short in stature with normal intelligence. Which hormone deficiency?" Answer: Growth Hormone (dwarfism). If mental retardation is added, it's thyroid hormone (cretinism).
5) Thyroid Gland
Butterfly-shaped gland in the neck, below the larynx. Consists of two lateral lobes connected by an isthmus over the trachea. Weighs ~25 g. Produces T₃ (triiodothyronine), T₄ (thyroxine), and calcitonin.
Hormones & Functions
| Hormone | Type | Function |
|---|---|---|
| T₄ (Thyroxine: 4 I atoms) T₃ (Triiodothyronine: 3 I atoms) | Amino acid derivative (from tyrosine + iodine) | Regulates basal metabolic rate (BMR) — controls how fast cells use energy. Also: growth, brain development (in children), heart rate, body temperature |
| Calcitonin | Peptide | Lowers blood Ca²⁺ — inhibits osteoclasts (bone breakdown), stimulates Ca²⁺ deposition in bones. Opposes PTH. |
Iodine requirement: Iodine is essential for T₃/T₄ synthesis. Dietary source: iodised salt, seaweed, fish. RDA: 150 µg/day.
Disorders of Thyroid Gland
Hypothyroidism (Low T₃/T₄):
- Goitre: Enlargement of thyroid gland due to iodine deficiency. The pituitary keeps secreting TSH trying to stimulate the thyroid, but without iodine the gland can't make T₃/T₄ → gland enlarges. Common in hilly areas where soil lacks iodine.
- Cretinism (childhood): Stunted growth + severe mental retardation + delayed puberty + coarse facial features + protruding tongue. Preventable with early iodine supplementation during pregnancy & infancy.
- Myxoedema (adulthood): Slowed metabolism → fatigue, weight gain, cold intolerance, dry skin, puffy face, hair loss, constipation, slow heart rate, depression. Treated with synthetic T₄ (levothyroxine).
- Hashimoto's Thyroiditis: Autoimmune — body attacks thyroid → progressive hypothyroidism. Most common cause in developed countries.
Hyperthyroidism (High T₃/T₄):
- Grave's Disease: Autoimmune — body stimulates thyroid excessively. Symptoms: exophthalmos (bulging eyes), goitre, weight loss despite increased appetite, heat intolerance, sweating, rapid heart rate (tachycardia), anxiety, tremors. Treated with anti-thyroid drugs, radioactive iodine, or surgery.
- Toxic nodular goitre (Plummer's disease): Thyroid nodules overproduce T₃/T₄, but no eye involvement (unlike Grave's).
💡 Goitre — two types (board favourite):
Simple goitre (endemic): Iodine deficiency → low T₃/T₄ → high TSH → thyroid enlarges. No heat/cold symptoms. Treated with iodine.
Exophthalmic goitre (Grave's): Autoimmune → high T₃/T₄ → thyroid enlarges + bulging eyes + hyperthyroidism symptoms. Treated with anti-thyroid drugs or surgery.
Both present with a swollen neck, but the hormone levels and symptoms are opposite. ICSE will give you symptoms and ask which type of goitre.
Simple goitre (endemic): Iodine deficiency → low T₃/T₄ → high TSH → thyroid enlarges. No heat/cold symptoms. Treated with iodine.
Exophthalmic goitre (Grave's): Autoimmune → high T₃/T₄ → thyroid enlarges + bulging eyes + hyperthyroidism symptoms. Treated with anti-thyroid drugs or surgery.
Both present with a swollen neck, but the hormone levels and symptoms are opposite. ICSE will give you symptoms and ask which type of goitre.
6) Parathyroid Glands
Four tiny glands (each ~6 mm, ~50 mg) embedded behind the thyroid gland. They produce Parathormone (PTH).
| Hormone | Target | Effect on Blood Ca²⁺ | Mechanism |
|---|---|---|---|
| PTH (Parathormone) | Bones, Kidneys, Intestine | Increases blood Ca²⁺ | → Bones: stimulates osteoclasts (Ca²⁺ released) → Kidneys: increases Ca²⁺ reabsorption, decreases phosphate reabsorption → Intestine: increases Ca²⁺ absorption (via Vitamin D activation) |
Note: PTH and Calcitonin (from thyroid) have opposite effects on blood Ca²⁺. They work together to maintain calcium homeostasis (normal level: 9–11 mg/dL).
Parathyroid Disorders:
- Hypoparathyroidism (low PTH): Low blood Ca²⁺ (hypocalcaemia) → nerve hyperexcitability → tetany (muscle spasms, cramps, tingling in fingers & lips, carpopedal spasm). Severe: laryngospasm → breathing difficulty. Treated with Ca²⁺ + Vitamin D supplements.
- Hyperparathyroidism (high PTH): High blood Ca²⁺ (hypercalcaemia) → bone pain & fractures (osteoporosis), kidney stones (Ca²⁺ deposits), fatigue, confusion. Usually due to parathyroid adenoma (tumour). Treated with surgery.
7) Adrenal Glands
Two glands (each ~5 g) sitting on top of each kidney. Each adrenal gland has two distinct parts — cortex (outer 80%) and medulla (inner 20%) — which are functionally and embryologically different.
Adrenal Cortex (Essential for Life — produces steroid hormones)
The cortex has 3 zones, each producing different hormones:
| Zone | Hormone | Type | Function |
|---|---|---|---|
| Zona Glomerulosa (outermost) | Aldosterone | Mineralocorticoid | Regulates Na⁺/K⁺ balance & blood pressure — increases Na⁺ reabsorption & K⁺ secretion in kidneys. Water follows Na⁺ → blood volume increases → BP increases. |
| Zona Fasciculata (middle, largest) | Cortisol | Glucocorticoid | "Stress hormone" — increases blood glucose (gluconeogenesis), suppresses immune system, anti-inflammatory, helps body cope with stress. Follows a circadian rhythm (highest in morning, lowest at night). |
| Zona Reticularis (innermost) | Androgens (DHEA, androstenedione) | Sex hormones (weak) | Contribute to growth of pubic & axillary hair, libido. In males, testosterone from testes is the main androgen; in females, these adrenal androgens are the primary source. |
Disorders of Adrenal Cortex
Hyposecretion Disorders:
- Addison's Disease (Primary adrenal insufficiency): Destruction of adrenal cortex → low cortisol + low aldosterone. Symptoms: hyperpigmentation (bronze skin — due to high ACTH stimulating melanocytes), fatigue, weight loss, low BP, hypoglycaemia, Na⁺ loss, K⁺ retention. Can be life-threatening during stress (Addisonian crisis). Treated with hydrocortisone + fludrocortisone.
Hypersecretion Disorders:
- Cushing's Syndrome: Excess cortisol → moon face, buffalo hump (fat on upper back), central obesity with thin arms/legs, purple stretch marks (striae), high BP, high blood sugar, osteoporosis, easy bruising. Causes: pituitary tumour (Cushing's Disease — high ACTH) or adrenal tumour. Treated with surgery.
- Conn's Syndrome (Primary Hyperaldosteronism): Excess aldosterone → high BP (hypertension) + low K⁺ (hypokalaemia) → muscle weakness, fatigue, frequent urination. Caused by adrenal adenoma. Treated with surgery or aldosterone antagonists (spironolactone).
- Adrenogenital Syndrome (Congenital Adrenal Hyperplasia): Excess androgens → virilisation (masculinisation) in females, early puberty in males.
Adrenal Medulla — "Fight or Flight" Response
The adrenal medulla is essentially a modified sympathetic ganglion. It produces catecholamines (adrenaline & noradrenaline).
| Hormone | % of Medulla | Effects (Mimics Sympathetic NS) |
|---|---|---|
| Adrenaline (Epinephrine) | ~80% | ↑ Heart rate & BP, ↑ blood glucose (glycogen breakdown), bronchodilation (wider airways), ↑ blood flow to muscles ↓ to skin/GI, ↑ mental alertness, pupil dilation. The dominant "fight or flight" hormone. |
| Noradrenaline (Norepinephrine) | ~20% | Similar but mainly causes vasoconstriction → ↑ BP. More involved in maintaining baseline BP. |
Adrenal Medulla Disorder:
- Phaeochromocytoma: Tumour of adrenal medulla → excess adrenaline/noradrenaline → episodes of severe hypertension, palpitations, sweating, headache, anxiety. Treated with surgery. Rare but important.
💡 Mnemonic for adrenal medulla effects — "Fight or Flight":
F — Faster heart rate
I — Increased blood pressure
G — Glucose release (more energy)
H — Hair standing up (piloerection — goosebumps)
T — To the muscles (blood diverted from skin/GI to muscles)
Short version: "Pupils dilate, lungs expand, heart races, liver releases sugar, muscles get blood."
F — Faster heart rate
I — Increased blood pressure
G — Glucose release (more energy)
H — Hair standing up (piloerection — goosebumps)
T — To the muscles (blood diverted from skin/GI to muscles)
Short version: "Pupils dilate, lungs expand, heart races, liver releases sugar, muscles get blood."
8) Pancreas — Islets of Langerhans
The pancreas is both an exocrine (digestive enzymes) and endocrine gland. The endocrine part consists of clusters of cells called Islets of Langerhans, containing 4 cell types:
| Cell Type | % of Islet | Hormone | Effect on Blood Glucose |
|---|---|---|---|
| α (Alpha) cells | ~20% | Glucagon | ↑ Increases blood glucose — stimulates glycogenolysis (liver glycogen → glucose) & gluconeogenesis (new glucose from amino acids) |
| β (Beta) cells | ~70% | Insulin | ↓ Decreases blood glucose — stimulates glucose uptake by cells (esp. muscle, fat), glycogen synthesis (liver & muscle), stops gluconeogenesis |
| δ (Delta) cells | ~5% | Somatostatin | Inhibits both insulin & glucagon release (paracrine regulation) |
| PP cells | ~5% | Pancreatic polypeptide | Regulates digestive functions (appetite, enzyme secretion) |
Disorders of Pancreas
Diabetes Mellitus:
A chronic metabolic disorder characterised by high blood glucose (hyperglycaemia) due to either insufficient insulin production or insulin resistance.
| Feature | Type 1 (IDDM) | Type 2 (NIDDM) |
|---|---|---|
| Cause | Autoimmune destruction of β cells → no/very little insulin | Insulin resistance (cells don't respond) + relative insulin deficiency |
| Age of onset | Childhood / adolescence | Adulthood (but increasing in younger due to obesity) |
| Body weight | Usually normal / thin | Usually overweight / obese |
| Treatment | Insulin injections (lifelong) — oral meds don't work | Diet + exercise + oral hypoglycaemic drugs (metformin); insulin may be needed in later stages |
| Ketoacidosis risk | High (fat breakdown → ketones → acidosis) | Low (some insulin still present) |
| Prevention | Not preventable (autoimmune) | Preventable — healthy lifestyle, weight control |
Symptoms (3 Ps):
- Polyuria: Frequent urination (excess glucose in urine pulls water by osmosis)
- Polydipsia: Excessive thirst (due to water loss)
- Polyphagia: Excessive hunger (cells can't use glucose → feel starved)
- Weight loss (Type 1), fatigue, blurred vision, slow wound healing, recurrent infections
Long-term complications (if uncontrolled): Cardiovascular disease, kidney failure (nephropathy), nerve damage (neuropathy), blindness (retinopathy), foot ulcers & amputations.
Hypoglycaemia (Low blood sugar — opposite):
- Can occur due to excess insulin (diabetic injecting too much), insulinoma (tumour of β cells), or starvation
- Symptoms: sweating, trembling, confusion, weakness, hunger, blurred vision. Severe: seizures, coma, death
- Treatment: Immediate glucose intake (fruit juice, sugar, or IV glucose)
⚠️ Diabetes Insipidus vs Diabetes Mellitus — CRITICAL distinction:
Diabetes Insipidus: ADH deficiency → excess urine + thirst. Blood sugar is NORMAL. Urine is dilute (watery).
Diabetes Mellitus: Insulin deficiency → high blood sugar + glucose in urine. Urine is sweet (mellitus = honey).
The word "Diabetes" means "to siphon/pass through" (excessive urination). The two conditions share polyuria & polydipsia but have completely different causes and treatments. ICSE LOVES this comparison.
Diabetes Insipidus: ADH deficiency → excess urine + thirst. Blood sugar is NORMAL. Urine is dilute (watery).
Diabetes Mellitus: Insulin deficiency → high blood sugar + glucose in urine. Urine is sweet (mellitus = honey).
The word "Diabetes" means "to siphon/pass through" (excessive urination). The two conditions share polyuria & polydipsia but have completely different causes and treatments. ICSE LOVES this comparison.
9) Other Endocrine Glands — Quick Reference
| Gland | Location | Hormone(s) | Function |
|---|---|---|---|
| Testes (♂) | Scrotum | Testosterone | Male secondary sexual characteristics, sperm production |
| Ovaries (♀) | Pelvis | Oestrogen, Progesterone | Female secondary sexual characteristics, menstrual cycle, pregnancy |
| Thymus | Upper chest (behind sternum) | Thymosin | T-lymphocyte maturation (immunity) |
| Pineal | Brain (between cerebral hemispheres) | Melatonin | Circadian rhythm (sleep-wake cycle) |
These glands are covered briefly in ICSE. Focus on the hormone names and their main functions from the table above. The gonads (testes & ovaries) are also known as sex glands — they're controlled by FSH and LH from the anterior pituitary.
10) Feedback Mechanisms — How Hormones Regulate Themselves
Most hormones are regulated by negative feedback loops — the output of the system counteracts the initial stimulus, maintaining balance (homeostasis).
Example: Thyroid Regulation (Hypothalamus-Pituitary-Thyroid Axis)
Negative feedback:
- Low T₃/T₄ levels → Hypothalamus releases TRH → Pituitary releases TSH → Thyroid releases T₃/T₄
- Rising T₃/T₄ levels → inhibit further TRH & TSH release (negative feedback) → T₃/T₄ production slows down
- If T₃/T₄ drops again → cycle repeats
Positive feedback (rare): Childbirth — oxytocin release → uterine contractions pressure on cervix → more oxytocin released → stronger contractions. The system amplifies the response rather than dampening it.
💡 Negative vs Positive feedback — key difference:
Negative feedback: The response reverses the initial change → maintains stability (homeostasis). Example: Thyroid regulation, body temperature, blood glucose, blood pressure.
Positive feedback: The response amplifies the initial change → leads to a climax/endpoint. Examples: Childbirth (oxytocin), blood clotting cascade, action potentials (nerve signals).
In the body, most systems use negative feedback. Positive feedback is reserved for processes that need to happen quickly and reach completion.
Negative feedback: The response reverses the initial change → maintains stability (homeostasis). Example: Thyroid regulation, body temperature, blood glucose, blood pressure.
Positive feedback: The response amplifies the initial change → leads to a climax/endpoint. Examples: Childbirth (oxytocin), blood clotting cascade, action potentials (nerve signals).
In the body, most systems use negative feedback. Positive feedback is reserved for processes that need to happen quickly and reach completion.
11) Complete Disorder Reference Table
| Gland | Hormone | Hyposecretion | Hypersecretion |
|---|---|---|---|
| Pituitary | GH | Dwarfism (childhood) | Gigantism (childhood), Acromegaly (adult) |
| Pituitary | ADH | Diabetes Insipidus | SIADH |
| Thyroid | T₃ / T₄ | Cretinism (child), Myxoedema (adult), Goitre | Grave's Disease, Exophthalmic goitre |
| Parathyroid | PTH | Tetany (hypocalcaemia) | Bone loss, kidney stones (hypercalcaemia) |
| Adrenal Cortex | Cortisol | Addison's Disease | Cushing's Syndrome |
| Adrenal Cortex | Aldosterone | Addison's (low BP, high K⁺) | Conn's Syndrome (high BP, low K⁺) |
| Adrenal Medulla | Adrenaline | — (minor effects) | Phaeochromocytoma (hypertension) |
| Pancreas | Insulin | Diabetes Mellitus Type 1 | Hypoglycaemia (insulinoma) |
| Pancreas | Glucagon | Hypoglycaemia | Hyperglycaemia (rare) |
| Testes | Testosterone | Delayed puberty, infertility | Early puberty (precocious) |
| Ovaries | Oestrogen | Delayed puberty, amenorrhoea | Early puberty (precocious) |
12) Common ICSE Board Questions
1-Mark Definitions & Match-Making:
- Define: Hormone, Endocrine gland, Exocrine gland, Target organ, Negative feedback
- Name the "master gland" of the body. Why is it called that?
- Which gland is called the "emergency gland" or "gland of fight or flight"?
- Name the only endocrine gland that is both exocrine and endocrine.
- Which hormone regulates blood sugar level? Which gland produces it?
- Name the hormone that regulates metabolism.
- Which hormone deficiency causes diabetes insipidus?
- Match: Gland → Hormone → Function (ICSE loves this format)
3-Mark Reasoning Questions:
- "The pituitary is called the master gland but it is controlled by the hypothalamus." Explain.
- Differentiate between endocrine and exocrine glands (any 4 points).
- Why is the pancreas called a "mixed gland"? Explain with its functions.
- Compare the effects of insulin and glucagon on blood glucose levels.
- Explain the "fight or flight" response triggered by adrenaline.
- What is the difference between diabetes insipidus and diabetes mellitus?
- Explain the negative feedback regulation of thyroid hormones (hypothalamus-pituitary-thyroid axis).
- A child is very short with normal intelligence. Another child is short with severe mental retardation. Which hormone deficiencies are responsible? Explain.
- Differentiate between cretinism and myxoedema.
- What is the role of calcitonin and how does it oppose PTH?
- Explain how aldosterone regulates blood pressure.
- A patient has high BP, low K⁺, and muscle weakness. Which gland and hormone are likely involved?
5-Mark Questions / Tables:
- Make a table listing 6 major endocrine glands, their locations, their hormones, and the functions of each hormone.
- Describe the causes, symptoms, and treatment of diabetes mellitus (Type 1 vs Type 2).
- Compare hyposecretion and hypersecretion disorders of: (a) Pituitary (GH), (b) Thyroid, (c) Adrenal cortex.
- Draw a labelled diagram of the endocrine glands in the human body (showing positions of pituitary, thyroid, parathyroid, adrenal, pancreas, ovaries/testes).
- Explain the negative feedback mechanism using the example of the thyroid gland. Draw a flowchart.
- Describe the causes, symptoms, and differences between Grave's disease and simple goitre.
- List the hormones produced by the anterior and posterior pituitary. State the functions of any 5.
- Explain how the body responds to a drop in blood sugar and a rise in blood sugar (roles of glucagon and insulin).
🧠 From my exam (93.4% scorer): The endocrine chapter is high-scoring because the questions are very predictable. ICSE follows a pattern:
1. "Matching" question — match gland with hormone with function (3-4 marks)
2. "Difference" question — endocrine vs exocrine, or insulin vs glucagon, or two disorders
3. "Explain the feedback" question — thyroid axis or blood glucose regulation
4. "Disease symptoms" question — diabetes, Grave's, Addison's, etc.
My advice: Make a one-page summary with GLAND → HORMONE → FUNCTION → DISORDER. Memorise that single page and you'll cover 80% of the chapter marks. The remaining 20% comes from understanding feedback mechanisms, which requires logic, not memorisation.
1. "Matching" question — match gland with hormone with function (3-4 marks)
2. "Difference" question — endocrine vs exocrine, or insulin vs glucagon, or two disorders
3. "Explain the feedback" question — thyroid axis or blood glucose regulation
4. "Disease symptoms" question — diabetes, Grave's, Addison's, etc.
My advice: Make a one-page summary with GLAND → HORMONE → FUNCTION → DISORDER. Memorise that single page and you'll cover 80% of the chapter marks. The remaining 20% comes from understanding feedback mechanisms, which requires logic, not memorisation.
13) Quick Reference Tables (Print This)
Glands That You MUST Know
| Gland | Hormone(s) | Main Function |
|---|---|---|
| Pituitary (Anterior) | GH, TSH, ACTH, FSH, LH, PRL | Controls growth, other glands, reproduction, milk production |
| Pituitary (Posterior) | ADH, Oxytocin | Water balance, childbirth, milk ejection |
| Thyroid | T₃, T₄, Calcitonin | Metabolism (BMR), growth, Ca²⁺ regulation |
| Parathyroid | PTH | ↑ Blood Ca²⁺ (opposes calcitonin) |
| Adrenal Cortex | Aldosterone, Cortisol, Androgens | Salt/water balance, stress response, sex hormone precursor |
| Adrenal Medulla | Adrenaline, Noradrenaline | "Fight or flight" — ↑ HR, BP, blood glucose |
| Pancreas (β cells) | Insulin | ↓ Blood glucose (promotes glucose uptake, storage) |
| Pancreas (α cells) | Glucagon | ↑ Blood glucose (glycogen breakdown) |
| Testes | Testosterone | Male sexual development, sperm production |
| Ovaries | Oestrogen, Progesterone | Female sexual development, menstrual cycle, pregnancy |
| Thymus | Thymosin | T-lymphocyte maturation (immunity) |
| Pineal | Melatonin | Sleep-wake cycle (circadian rhythm) |
Disorders Quick Summary
| Disorder | Gland | Cause | Key Symptom |
|---|---|---|---|
| Dwarfism | Pituitary | Low GH (childhood) | Short stature, normal IQ |
| Gigantism | Pituitary | High GH (childhood) | Excessive height |
| Acromegaly | Pituitary | High GH (adulthood) | Enlarged hands, feet, jaw |
| Diabetes Insipidus | Pituitary | Low ADH | Excess urine + thirst |
| Cretinism | Thyroid | Low T₄ (childhood) | Short stature + mental retardation |
| Myxoedema | Thyroid | Low T₄ (adult) | Weight gain, fatigue, cold intolerance |
| Grave's Disease | Thyroid | High T₄ | Bulging eyes, weight loss, goitre |
| Goitre (Simple) | Thyroid | Iodine deficiency | Enlarged thyroid, normal hormone |
| Tetany | Parathyroid | Low PTH → low Ca²⁺ | Muscle spasms, cramps |
| Addison's Disease | Adrenal Cortex | Low Cortisol | Hyperpigmentation, fatigue, low BP |
| Cushing's Syndrome | Adrenal Cortex | High Cortisol | Moon face, buffalo hump, high BP |
| Conn's Syndrome | Adrenal Cortex | High Aldosterone | High BP, low K⁺ |
| Phaeochromocytoma | Adrenal Medulla | High Adrenaline | Episodic hypertension, sweating |
| Diabetes Mellitus (T1) | Pancreas | Low/No Insulin | High blood sugar, weight loss, 3 Ps |
⚠️ Final advice from my exam: The endocrine chapter is where ICSE tests your ability to connect. A single question can connect: "A patient has high blood pressure, low potassium, and muscle weakness. Name the gland, hormone, and disorder." You need to connect adrenal cortex → aldosterone → Conn's syndrome. Don't learn glands in isolation — learn them as gland → hormone → function → disorder chains. This is the only way to handle the board's application-based questions.