# Chemical Coordination and Integration (NEET Biology Class 11): Every Hormone, Gland & Disorder

Source: https://tracknation.in/story/chemical-coordination-and-integration-neet-biology-class-11-every-hormone-gland-disorder (TrackNation — free UPSC notes with PYQs)

> NEET Class 11 Chemical Coordination and Integration, mined from NCERT: the hypothalamus (releasing vs inhibiting hormones) and a complete pituitary hormone table with functions and disorders (gigantism, dwarfism, acromegaly, diabetes insipidus), a master reference table for the pineal, thyroid, parathyroid, thymus, adrenal medulla and cortex, pancreas, testis and ovary with every hormone, function and disorder (goitre, cretinism, Graves' disease, Addison's disease, diabetes mellitus), a table of

## Hormones, Hypothalamus & the Pituitary Gland

📌 **NEET priority: Important.** *2–4 questions a year — and nearly all are **match-the-hormone-to-its-gland-and-function** or **which hormone disorder is which**. The two master tables below cover the entire chapter.*

**Hormones are non-nutrient chemicals that act as intercellular messengers and are
produced in trace amounts.** Endocrine glands lack ducts — hence **ductless
glands**. The organised endocrine bodies are: **pituitary, pineal, thyroid, adrenal,
pancreas, parathyroid, thymus and gonads** (testis/ovary). The
**gastrointestinal tract, liver, kidney and heart** also produce hormones.

### Hypothalamus & pituitary — the control hierarchy

- The **hypothalamus** (basal part of the diencephalon, forebrain) contains
neurosecretory cells called **nuclei** producing two hormone types:
**releasing hormones** (stimulate pituitary secretion — e.g.
**GnRH** stimulating gonadotrophins) and **inhibiting hormones**
(e.g. **somatostatin** inhibiting growth hormone release).

- These reach the **anterior pituitary via a portal circulatory system**. The
**posterior pituitary is under DIRECT NEURAL regulation** of the hypothalamus.

- The pituitary sits in a bony cavity called the **sella tursica**. It has an
**adenohypophysis** (= **pars distalis**, the anterior pituitary, +
**pars intermedia**) and a **neurohypophysis** (**pars nervosa**,
the posterior pituitary). In humans **pars intermedia is almost merged with pars
distalis**.

- **Crucial:** the posterior pituitary **only STORES and RELEASES**
oxytocin and vasopressin — they are actually **synthesised by the hypothalamus** and
transported axonally.

| **Pituitary part**

 | **Hormone**

 | **Function**

 |
| Pars distalis (anterior)

 | Growth Hormone (GH)

 | Body growth. EXCESS in childhood → GIGANTISM; DEFICIENCY → PITUITARY DWARFISM; EXCESS in adults → ACROMEGALY (severe facial disfigurement)

 |
| Pars distalis

 | Prolactin (PRL)

 | Growth of mammary glands and formation of milk

 |
| Pars distalis

 | Thyroid Stimulating Hormone (TSH)

 | Stimulates synthesis and secretion of thyroid hormones

 |
| Pars distalis

 | Adrenocorticotrophic Hormone (ACTH)

 | Stimulates glucocorticoid secretion from the ADRENAL CORTEX

 |
| Pars distalis

 | Luteinising Hormone (LH)

 | MALES: stimulates androgen secretion from testis. FEMALES: induces OVULATION of the Graafian follicle and maintains the corpus luteum

 |
| Pars distalis

 | Follicle Stimulating Hormone (FSH)

 | MALES: with androgens, regulates spermatogenesis. FEMALES: stimulates growth/development of ovarian follicles

 |
| Pars intermedia

 | Melanocyte Stimulating Hormone (MSH)

 | Acts on melanocytes, regulating skin pigmentation

 |
| Neurohypophysis (posterior)

 | Oxytocin

 | Contracts smooth muscle — vigorous UTERINE contraction at childbirth and MILK EJECTION

 |
| Neurohypophysis (posterior)

 | Vasopressin (ADH)

 | Acts on the kidney — resorption of water and electrolytes by the DISTAL TUBULES, reducing diuresis. Impairment → DIABETES INSIPIDUS

 |

## The Endocrine Glands — Master Reference Table

### The remaining endocrine glands — the master table

| **Gland**

 | **Hormone(s)**

 | **Function**

 | **Disorder**

 |
| Pineal (dorsal side of forebrain)

 | Melatonin

 | Regulates the 24-hour DIURNAL rhythm — sleep-wake cycle, body temperature; also influences metabolism, pigmentation, menstrual cycle and defence capability

 | —

 |
| Thyroid (two lobes joined by an ISTHMUS)

 | Thyroxine (T₄) and Triiodothyronine (T₃) — need IODINE. Also thyrocalcitonin (TCT)

 | Regulate BASAL METABOLIC RATE; support RBC formation; control carbohydrate/protein/fat metabolism and water-electrolyte balance. TCT regulates blood CALCIUM

 | Iodine deficiency → HYPOTHYROIDISM and GOITRE. In pregnancy → CRETINISM (stunted growth, mental retardation, deaf-mutism). Excess → HYPERTHYROIDISM; EXOPHTHALMIC GOITRE (Graves' disease) with protruding eyeballs and weight loss

 |
| Parathyroid (FOUR glands, on the BACK of the thyroid)

 | Parathyroid Hormone (PTH)

 | HYPERCALCEMIC — INCREASES blood Ca²⁺ by bone resorption, renal reabsorption of Ca²⁺, and increased absorption from food. Opposes TCT

 | —

 |
| Thymus (between lungs, behind sternum)

 | Thymosins

 | Differentiation of T-LYMPHOCYTES (cell-mediated immunity); also promote antibody production (humoral immunity). DEGENERATES in old age → weak immunity

 | —

 |
| Adrenal MEDULLA (centre)

 | Adrenaline (epinephrine) and Noradrenaline — the CATECHOLAMINES

 | EMERGENCY / 'FIGHT OR FLIGHT' hormones. Increase alertness, pupillary dilation, piloerection, sweating, heart rate, contraction strength and respiration rate. Break down glycogen, lipids and proteins

 | —

 |
| Adrenal CORTEX (outer; layers = zona reticularis, fasciculata, glomerulosa)

 | Glucocorticoids (mainly CORTISOL) and Mineralocorticoids (mainly ALDOSTERONE)

 | Cortisol: gluconeogenesis, lipolysis, proteolysis; anti-inflammatory; SUPPRESSES immune response; stimulates RBC production. Aldosterone: reabsorbs Na⁺ and water, excretes K⁺ and phosphate — maintains blood pressure

 | UNDERPRODUCTION → ADDISON'S DISEASE (acute weakness and fatigue)

 |
| Pancreas — Islets of Langerhans (1–2 million; only 1–2% of pancreatic tissue)

 | α-cells → GLUCAGON; β-cells → INSULIN

 | Glucagon: HYPERglycemic — glycogenolysis and gluconeogenesis in hepatocytes. Insulin: HYPOglycemic — enhances glucose uptake by hepatocytes and adipocytes, and glycogenesis

 | Prolonged hyperglycemia → DIABETES MELLITUS (glucose lost in urine, ketone bodies formed). Treated with insulin therapy

 |
| Testis (Leydig/interstitial cells)

 | Androgens, mainly TESTOSTERONE

 | Develop male accessory sex organs; muscular growth, facial/axillary hair, aggressiveness, low-pitched voice; stimulate SPERMATOGENESIS; influence male sexual behaviour; anabolic effects

 | —

 |
| Ovary

 | Estrogen (from growing follicles) and Progesterone (from the CORPUS LUTEUM)

 | Estrogen: female secondary sex organs and characters, follicle development, mammary gland development, sexual behaviour. Progesterone: SUPPORTS PREGNANCY; stimulates mammary ALVEOLI formation and milk secretion

 | —

 |

## Non-Endocrine Hormones, Mechanism of Action & Why This Matters for NEET

### Hormones from non-endocrine tissues

| **Source**

 | **Hormone**

 | **Action**

 |
| Atrial wall of the HEART

 | Atrial Natriuretic Factor (ANF)

 | DECREASES blood pressure by dilating blood vessels

 |
| Juxtaglomerular cells of the KIDNEY

 | Erythropoietin

 | Stimulates erythropoiesis — formation of RBCs

 |
| Gastrointestinal tract

 | Gastrin

 | Acts on gastric glands — stimulates secretion of HCl and pepsinogen

 |
| Gastrointestinal tract

 | Secretin

 | Acts on exocrine pancreas — stimulates secretion of water and bicarbonate ions

 |
| Gastrointestinal tract

 | Cholecystokinin (CCK)

 | Acts on pancreas AND gall bladder — stimulates pancreatic enzymes and bile juice

 |
| Gastrointestinal tract

 | Gastric Inhibitory Peptide (GIP)

 | INHIBITS gastric secretion and motility

 |

### Mechanism of hormone action

- Hormones bind **specific hormone receptors** found only in target tissues,
forming a **hormone-receptor complex**. **Each receptor is specific to one
hormone**. Receptors are either **membrane-bound** (on the cell membrane) or
**intracellular** (mostly nuclear).

- **Four chemical classes of hormones:** (1) **peptide/polypeptide/
protein** — insulin, glucagon, pituitary and hypothalamic hormones; (2) **steroids**
— cortisol, testosterone, estradiol, progesterone; (3) **iodothyronines** — thyroid
hormones; (4) **amino-acid derivatives** — epinephrine.

- **Membrane-bound receptor hormones** normally **do NOT enter the
cell** — they generate **second messengers** (cyclic AMP, IP₃, Ca²⁺) that
regulate cellular metabolism. **Intracellular receptor hormones** (steroids,
iodothyronines) mostly **regulate gene expression or chromosome function**.

### Why this matters for NEET

- High-value one-liners: posterior pituitary **only stores** oxytocin/
vasopressin (hypothalamus makes them); GH excess = **gigantism (child) / acromegaly
(adult)**; iodine deficiency = **goitre + cretinism**; Graves' disease =
**exophthalmic goitre**; adrenal cortex deficiency = **Addison's
disease**; α-cells = **glucagon**, β-cells = **insulin**;
**ANF lowers BP**; **erythropoietin** from the kidney.

- **Trap:** **Diabetes INSIPIDUS** (ADH problem → water loss) is
completely different from **diabetes MELLITUS** (insulin problem → high blood
glucose) — the shared name catches students out every year. Also, **PTH raises blood
calcium** while **TCT lowers it** — they are antagonists. And
**adrenal MEDULLA** makes the fight-or-flight catecholamines while the
**adrenal CORTEX** makes the corticoids — swapping them loses the mark.

## Test Yourself: MCQs, PYQs & Active Recall

Answer these, then close the article and do an Active Recall. Reveal each answer only after you commit to one.

## Practice Questions

**Q1.** Hormones are best defined as:

- (a) Proteins that digest food

- (b) Nutrient chemicals produced in large amounts

- (c) Non-nutrient chemicals acting as intercellular messengers in trace amounts

- (d) Enzymes produced by ducted glands

**Answer: (c)** — Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts.

**Q2.** The pituitary gland is located in a bony cavity called the:

- (a) Sella tursica

- (b) Hilum

- (c) Glenoid cavity

- (d) Acetabulum

**Answer: (a)** — The pituitary sits in the sella tursica and is attached to the hypothalamus by a stalk.

**Q3.** Oxytocin and vasopressin are actually synthesised by the:

- (a) Pineal gland

- (b) Hypothalamus

- (c) Anterior pituitary

- (d) Posterior pituitary

**Answer: (b)** — They are synthesised by the hypothalamus and transported axonally to the neurohypophysis, which only stores and releases them.

**Q4.** Excess secretion of growth hormone in an adult causes:

- (a) Cretinism

- (b) Acromegaly

- (c) Gigantism

- (d) Pituitary dwarfism

**Answer: (b)** — Excess GH in childhood causes gigantism; in adults it causes acromegaly, with severe facial disfigurement.

**Q5.** Melanocyte Stimulating Hormone (MSH) is secreted by the:

- (a) Pineal gland

- (b) Pars nervosa

- (c) Pars intermedia

- (d) Pars distalis

**Answer: (c)** — Pars intermedia secretes only MSH, which acts on melanocytes and regulates skin pigmentation.

**Q6.** Impaired synthesis or release of ADH leads to:

- (a) Addison's disease

- (b) Diabetes insipidus

- (c) Graves' disease

- (d) Diabetes mellitus

**Answer: (b)** — Reduced ADH diminishes the kidney's ability to conserve water, causing water loss and dehydration — diabetes insipidus.

**Q7.** Melatonin, which regulates the 24-hour diurnal rhythm, is secreted by the:

- (a) Adrenal medulla

- (b) Thymus

- (c) Thyroid

- (d) Pineal gland

**Answer: (d)** — The pineal gland, on the dorsal side of the forebrain, secretes melatonin.

**Q8.** The two lobes of the thyroid gland are interconnected by a thin flap of tissue called the:

- (a) Septum

- (b) Isthmus

- (c) Capsule

- (d) Stalk

**Answer: (b)** — Both thyroid lobes are interconnected by a thin flap of connective tissue called the isthmus.

**Q9.** Hypothyroidism during pregnancy causes which condition in the baby?

- (a) Graves' disease

- (b) Addison's disease

- (c) Cretinism

- (d) Acromegaly

**Answer: (c)** — Hypothyroidism in pregnancy causes defective development leading to cretinism — stunted growth, mental retardation and deaf-mutism.

**Q10.** Exophthalmic goitre, also called Graves' disease, is a form of:

- (a) Hypoparathyroidism

- (b) Hypothyroidism

- (c) Diabetes

- (d) Hyperthyroidism

**Answer: (d)** — Graves' disease is hyperthyroidism, with enlarged thyroid, protruding eyeballs, raised BMR and weight loss.

**Q11.** Parathyroid hormone (PTH) is best described as:

- (a) A hormone that regulates sodium only

- (b) A hormone that lowers blood glucose

- (c) A hypocalcemic hormone

- (d) A hypercalcemic hormone that raises blood Ca2+

**Answer: (d)** — PTH is hypercalcemic — it raises blood Ca2+ by bone resorption, renal reabsorption and increased dietary absorption.

**Q12.** Thymosins, secreted by the thymus, are important for:

- (a) Skin pigmentation

- (b) Differentiation of T-lymphocytes and antibody production

- (c) Glucose metabolism

- (d) Bone growth

**Answer: (b)** — Thymosins differentiate T-lymphocytes for cell-mediated immunity and promote antibody production for humoral immunity.

**Q13.** Adrenaline and noradrenaline are secreted by the adrenal:

- (a) Zona glomerulosa

- (b) Medulla

- (c) Cortex

- (d) Capsule

**Answer: (b)** — The adrenal medulla secretes the catecholamines adrenaline and noradrenaline — the fight-or-flight hormones.

**Q14.** Underproduction of hormones by the adrenal cortex causes:

- (a) Addison's disease

- (b) Diabetes insipidus

- (c) Graves' disease

- (d) Acromegaly

**Answer: (a)** — Adrenal cortex underproduction alters carbohydrate metabolism causing acute weakness and fatigue — Addison's disease.

**Q15.** The main mineralocorticoid in the human body is:

- (a) Aldosterone

- (b) Testosterone

- (c) Cortisol

- (d) Adrenaline

**Answer: (a)** — Aldosterone is the main mineralocorticoid, regulating water and electrolyte balance; cortisol is the main glucocorticoid.

**Q16.** In the Islets of Langerhans, insulin is secreted by:

- (a) Delta cells

- (b) Beta cells

- (c) Alpha cells

- (d) Acinar cells

**Answer: (b)** — Beta cells secrete insulin (hypoglycemic) while alpha cells secrete glucagon (hyperglycemic).

**Q17.** The Islets of Langerhans represent approximately what percentage of pancreatic tissue?

- (a) 1-2 per cent

- (b) 90 per cent

- (c) 10 per cent

- (d) 50 per cent

**Answer: (a)** — There are 1 to 2 million Islets of Langerhans, representing only 1 to 2 per cent of the pancreatic tissue.

**Q18.** Hormones that interact with membrane-bound receptors act by:

- (a) Regulating chromosome function

- (b) Entering the cell and binding DNA

- (c) Directly digesting the target cell

- (d) Generating second messengers such as cyclic AMP

**Answer: (d)** — They normally do not enter the cell but generate second messengers (cyclic AMP, IP3, Ca++) that regulate cellular metabolism.

### NEET Previous Year Questions (PYQs)

*Real NEET previous-year questions on this chapter, with explanations in our own words.*

**Q19.** Atrial Natriuretic Factor (ANF), secreted by the heart, acts to: (NEET PYQ)

- (a) Increase blood pressure

- (b) Stimulate RBC formation

- (c) Decrease blood pressure by dilating blood vessels

- (d) Increase heart rate

**Answer: (c)** — ANF is secreted when blood pressure rises; it dilates blood vessels and thereby reduces blood pressure.

**Q20.** Erythropoietin, which stimulates RBC formation, is produced by: (NEET PYQ)

- (a) Juxtaglomerular cells of the kidney

- (b) Bone marrow

- (c) The spleen

- (d) The liver

**Answer: (a)** — The juxtaglomerular cells of the kidney produce the peptide hormone erythropoietin, stimulating erythropoiesis.

**Q21.** Which gastrointestinal hormone stimulates the secretion of HCl and pepsinogen? (NEET PYQ)

- (a) CCK

- (b) Secretin

- (c) GIP

- (d) Gastrin

**Answer: (d)** — Gastrin acts on the gastric glands to stimulate secretion of hydrochloric acid and pepsinogen.

**Q22.** Cholecystokinin (CCK) acts on: (NEET PYQ)

- (a) Both the pancreas and gall bladder

- (b) Only the stomach

- (c) The kidney

- (d) Only the liver

**Answer: (a)** — CCK acts on both pancreas and gall bladder, stimulating pancreatic enzymes and bile juice respectively.

**Q23.** Progesterone is secreted mainly by the: (NEET PYQ)

- (a) Adrenal cortex

- (b) Corpus luteum

- (c) Anterior pituitary

- (d) Growing ovarian follicles

**Answer: (b)** — After ovulation the ruptured follicle becomes the corpus luteum, which secretes mainly progesterone; estrogen comes from growing follicles.

**Q24.** Which hypothalamic hormone inhibits the release of growth hormone? (NEET PYQ)

- (a) Somatostatin

- (b) ACTH

- (c) TSH

- (d) GnRH

**Answer: (a)** — Somatostatin from the hypothalamus is an inhibiting hormone that blocks growth hormone release from the pituitary.

**Q25.** Steroid hormones and iodothyronines act mainly by: (NEET PYQ)

- (a) Generating cyclic AMP

- (b) Digesting cell membranes

- (c) Regulating gene expression via intracellular receptors

- (d) Binding membrane receptors only

**Answer: (c)** — Hormones interacting with intracellular receptors mostly regulate gene expression or chromosome function.

**Q26.** Testosterone is produced by which cells of the testis? (NEET PYQ)

- (a) Spermatogonia

- (b) Leydig or interstitial cells

- (c) Germ cells

- (d) Sertoli cells

**Answer: (b)** — The Leydig or interstitial cells present in the intertubular spaces produce androgens, mainly testosterone.

### Active Recall Prompt

Write everything you can recall about **Chemical Coordination and Integration**, naming each gland or hormone first: the definition of a **hormone** and the list of endocrine glands; the **hypothalamus** (releasing vs inhibiting hormones) and the **pituitary** (its parts and every hormone with its function and disorders); then for each of the **pineal, thyroid, parathyroid, thymus, adrenal medulla and cortex, pancreas, testis and ovary** — the hormone(s), their functions and the associated disorders; the **hormones from heart, kidney and the gastrointestinal tract**; and the **mechanism of hormone action** (receptor types, the four chemical classes, second messengers). Begin each fact with its topic and end it with a full stop.