Chemical Coordination and Integration is Chapter 19 of NCERT Class 11 Biology and part of Unit 5, Human Physiology, of the NEET UG syllabus. These notes cover endocrine glands and hormones, the hypothalamus, pituitary, pineal, thyroid, parathyroid, thymus, adrenal, pancreas and gonads, hormones of the heart, kidney and gut, hormone disorders and how hormones act, with a free PDF.
Chemical Coordination and Integration NEET Notes
Gland-wise key points from NCERT Chapter 19, hormone tables, high-yield facts and common mistakes for NEET 2027 revision.
Chemical Coordination and Integration at a Glance
| Item | Details |
|---|---|
| NEET UG syllabus unit | Unit 5: Human Physiology |
| NCERT textbook | Biology, Class 11, Chapter 19 (rationalised book) |
| Other chapters in the unit | Breathing and Exchange of Gases (Chapter 14), Body Fluids and Circulation (Chapter 15), Excretory Products and their Elimination (Chapter 16), Locomotion and Movement (Chapter 17), Neural Control and Coordination (Chapter 18) |
| Syllabus topics | Endocrine glands and hormones; human endocrine system: hypothalamus, pituitary, pineal, thyroid, parathyroid, adrenal, pancreas, gonads; mechanism of hormone action (elementary idea); hormones as messengers and regulators; hypo- and hyperactivity and related disorders (dwarfism, acromegaly, cretinism, goitre, exophthalmic goitre, diabetes, Addison’s disease) |
| Official chapter | NCERT Chapter 19 |
| Notes PDF | View PDF |
The topic list follows the NEET UG 2026 syllabus released by the National Medical Commission (NMC) on 22 December 2025, which stays the reference until the 2027 syllabus is out. The full list is on the NEET syllabus page.
What are endocrine glands and hormones?
Endocrine glands lack ducts, so they are called ductless glands, and their secretions are called hormones.
- Neural coordination is fast but short-lived and nerve fibres do not reach all cells, so continuous regulation is provided by hormones. The neural and endocrine systems jointly coordinate body functions.
- Current definition: hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts.
- Organised endocrine bodies: pituitary, pineal, thyroid, adrenal, pancreas, parathyroid, thymus and gonads (testis in males, ovary in females).
- Other organs that also produce hormones: gastrointestinal tract, liver, kidney and heart.
- Invertebrates have very simple endocrine systems with few hormones; vertebrates use a large number of chemicals as hormones.
Hypothalamus and Pituitary Gland
The hypothalamus, the basal part of the diencephalon of the forebrain, controls the pituitary through releasing and inhibiting hormones made by its neurosecretory cells (nuclei).
- Releasing hormones stimulate pituitary secretion (e.g., gonadotrophin releasing hormone, GnRH, stimulates release of gonadotrophins). Inhibiting hormones stop it (e.g., somatostatin inhibits release of growth hormone).
- Hypothalamic hormones pass through axons and reach the anterior pituitary through a portal circulatory system. The posterior pituitary is under direct neural regulation of the hypothalamus.
- The pituitary lies in a bony cavity, the sella tursica, attached to the hypothalamus by a stalk.
- Adenohypophysis = pars distalis (anterior pituitary) + pars intermedia. Neurohypophysis = pars nervosa (posterior pituitary). In humans the pars intermedia is almost merged with the pars distalis.
| Hormone | Part of pituitary | Main action |
|---|---|---|
| Growth hormone (GH) | Pars distalis | Growth of the body |
| Prolactin (PRL) | Pars distalis | Growth of mammary glands and formation of milk |
| Thyroid stimulating hormone (TSH) | Pars distalis | Synthesis and secretion of thyroid hormones |
| Adrenocorticotrophic hormone (ACTH) | Pars distalis | Synthesis and secretion of glucocorticoids from the adrenal cortex |
| Luteinizing hormone (LH) | Pars distalis | Males: androgen secretion from testis. Females: ovulation of graafian follicles and maintenance of the corpus luteum |
| Follicle stimulating hormone (FSH) | Pars distalis | Males: with androgens, regulates spermatogenesis. Females: growth and development of ovarian follicles |
| Melanocyte stimulating hormone (MSH) | Pars intermedia | Acts on melanocytes; regulates skin pigmentation |
| Oxytocin | Pars nervosa (made in hypothalamus) | Contraction of smooth muscles: uterus at child birth, milk ejection |
| Vasopressin (ADH) | Pars nervosa (made in hypothalamus) | Reabsorption of water and electrolytes by distal tubules; reduces diuresis |
Pituitary Disorders
| Condition | Cause |
|---|---|
| Gigantism | Over-secretion of GH |
| Pituitary dwarfism | Low secretion of GH (stunted growth) |
| Acromegaly | Excess GH in adults, especially in middle age; severe disfigurement, especially of the face; hard to diagnose early |
| Diabetes insipidus | Impaired synthesis or release of ADH; kidney cannot conserve water, causing water loss and dehydration |
Pineal, Thyroid, Parathyroid and Thymus
These four glands control body rhythms, metabolic rate, blood calcium and immunity.
Pineal Gland
- Located on the dorsal side of the forebrain; secretes melatonin.
- Melatonin regulates the 24-hour (diurnal) rhythm, such as the sleep-wake cycle and body temperature, and also influences metabolism, pigmentation, the menstrual cycle and defence capability.
Thyroid Gland
- Two lobes on either side of the trachea, joined by a thin flap of connective tissue, the isthmus. It is made of follicles and stromal tissue.
- Follicular cells make tetraiodothyronine or thyroxine (T4) and triiodothyronine (T3). Iodine is essential for their normal synthesis.
- Thyroid hormones regulate the basal metabolic rate, support red blood cell formation, control metabolism of carbohydrates, proteins and fats, and influence water and electrolyte balance.
- The thyroid also secretes thyrocalcitonin (TCT), a protein hormone that lowers blood calcium levels.
| Thyroid condition | Cause and features |
|---|---|
| Goitre | Iodine deficiency causes hypothyroidism and enlargement of the thyroid gland |
| Cretinism | Hypothyroidism during pregnancy: stunted growth, mental retardation, low IQ, abnormal skin, deaf-mutism in the baby |
| Hypothyroidism in adult women | Irregular menstrual cycle |
| Hyperthyroidism | Abnormally high hormone levels due to cancer or nodules of the thyroid |
| Exophthalmic goitre (Graves’ disease) | Form of hyperthyroidism: enlarged thyroid, protruding eyeballs, increased BMR, weight loss |
Parathyroid Glands
- Four glands on the back side of the thyroid, one pair in each lobe. They secrete parathyroid hormone (PTH), a peptide hormone whose secretion is regulated by circulating calcium ions.
- PTH is hypercalcemic: it stimulates bone resorption (demineralisation), reabsorption of Ca2+ by renal tubules and Ca2+ absorption from digested food. Along with TCT it maintains calcium balance.
Thymus
- A lobular gland between the lungs, behind the sternum, on the ventral side of the aorta.
- It secretes thymosins, peptide hormones that drive differentiation of T-lymphocytes (cell-mediated immunity) and promote antibody production (humoral immunity).
- The thymus degenerates in old individuals, so their immune responses become weak.
Adrenal Gland: Medulla and Cortex
One adrenal gland sits above each kidney; the central tissue is the adrenal medulla and the outer tissue is the adrenal cortex.
| Part | Hormones | Main actions |
|---|---|---|
| Adrenal medulla | Adrenaline (epinephrine) and noradrenaline (norepinephrine), the catecholamines | Emergency or ‘fight or flight’ hormones: alertness, pupillary dilation, piloerection, sweating, faster and stronger heart beat, faster respiration, breakdown of glycogen (raising blood glucose), lipids and proteins |
| Adrenal cortex: glucocorticoids | Cortisol (main glucocorticoid) | Gluconeogenesis, lipolysis and proteolysis; inhibit cellular uptake of amino acids; maintain cardio-vascular and kidney functions; anti-inflammatory and immune-suppressing; stimulate RBC production |
| Adrenal cortex: mineralocorticoids | Aldosterone (main mineralocorticoid) | Reabsorption of Na+ and water and excretion of K+ and phosphate at renal tubules; maintains electrolytes, body fluid volume, osmotic pressure and blood pressure |
| Adrenal cortex: androgenic steroids | Small amounts | Growth of axial, pubic and facial hair during puberty |
- Layers of the adrenal cortex from inside out: zona reticularis (inner), zona fasciculata (middle), zona glomerulosa (outer).
- Underproduction of adrenal cortex hormones alters carbohydrate metabolism and causes acute weakness and fatigue: Addison’s disease.
Pancreas: Insulin and Glucagon
The pancreas is a composite gland, both exocrine and endocrine; its endocrine part is the Islets of Langerhans.
- A normal human pancreas has about 1 to 2 million islets, only 1 to 2 per cent of pancreatic tissue.
- The two main cell types are alpha cells (glucagon) and beta cells (insulin).
| Feature | Glucagon | Insulin |
|---|---|---|
| Secreted by | Alpha cells | Beta cells |
| Chemical nature | Peptide hormone | Peptide hormone |
| Main target | Liver cells (hepatocytes) | Hepatocytes and adipocytes |
| Action | Glycogenolysis and gluconeogenesis; reduces cellular glucose uptake | Increases cellular glucose uptake and utilisation; glycogenesis |
| Effect on blood glucose | Hyperglycemic (raises it) | Hypoglycemic (lowers it) |
Prolonged hyperglycemia leads to diabetes mellitus, with loss of glucose in urine and formation of harmful ketone bodies; patients are treated with insulin therapy.
Testis and Ovary
The gonads are primary sex organs and endocrine glands at the same time.
| Gonad | Hormone source | Main actions |
|---|---|---|
| Testis | Leydig (interstitial) cells in the intertubular spaces make androgens, mainly testosterone | Development and function of male accessory sex organs; muscular growth, facial and axillary hair, low pitch of voice; spermatogenesis; male sexual behaviour (libido); anabolic effects on protein and carbohydrate metabolism |
| Ovary: estrogen | Mainly the growing ovarian follicles | Growth of female secondary sex organs, development of follicles, female secondary sex characters (e.g., high pitch of voice), mammary gland development, female sexual behaviour |
| Ovary: progesterone | Corpus luteum (formed from the ruptured follicle after ovulation) | Supports pregnancy; stimulates formation of mammary alveoli and milk secretion |
Hormones of Heart, Kidney and Gastrointestinal Tract
Some tissues that are not endocrine glands also secrete hormones.
| Hormone | Source | Action |
|---|---|---|
| Atrial natriuretic factor (ANF) | Atrial wall of the heart | Dilates blood vessels and decreases blood pressure |
| Erythropoietin | Juxtaglomerular cells of the kidney | Stimulates erythropoiesis (RBC formation) |
| Gastrin | Gastrointestinal tract | Acts on gastric glands; secretion of hydrochloric acid and pepsinogen |
| Secretin | Gastrointestinal tract | Acts on exocrine pancreas; secretion of water and bicarbonate ions |
| Cholecystokinin (CCK) | Gastrointestinal tract | Acts on pancreas and gall bladder; secretion of pancreatic enzymes and bile juice |
| Gastric inhibitory peptide (GIP) | Gastrointestinal tract | Inhibits gastric secretion and motility |
Several other non-endocrine tissues secrete growth factors, which are essential for normal growth, repair and regeneration of tissues.
How do hormones act on target cells?
Hormones act by binding to specific hormone receptors present only in target tissues, forming a hormone-receptor complex; each receptor is specific to one hormone.
| Feature | Membrane-bound receptors | Intracellular receptors |
|---|---|---|
| Location | Cell membrane of the target cell | Inside the target cell, mostly nuclear receptors |
| Examples of hormones | Protein or peptide hormones such as insulin and glucagon | Steroid hormones, iodothyronines |
| Entry into cell | Normally do not enter the cell | Act inside the cell |
| How they act | Generate second messengers (cyclic AMP, IP3, Ca++) that regulate metabolism | Regulate gene expression or chromosome function via the hormone-receptor complex |
- Peptide, polypeptide and protein hormones: insulin, glucagon, pituitary and hypothalamic hormones.
- Steroids: cortisol, testosterone, estradiol and progesterone.
- Iodothyronines: thyroid hormones.
- Amino-acid derivatives: epinephrine.
Most-asked Facts for NEET: Chemical Coordination and Integration
Revise these one-line facts from the NCERT chapter just before the exam.
- Hormones are non-nutrient chemicals, act as intercellular messengers and are produced in trace amounts.
- GnRH stimulates gonadotrophin release; somatostatin inhibits growth hormone release.
- The pituitary sits in the sella tursica; the anterior pituitary is reached by a portal circulation.
- Pars distalis makes six hormones (GH, PRL, TSH, ACTH, LH, FSH); pars intermedia makes MSH.
- Oxytocin and vasopressin are made in the hypothalamus and released from the posterior pituitary.
- ADH deficiency causes diabetes insipidus.
- Excess GH: gigantism (children), acromegaly (adults); low GH: pituitary dwarfism.
- Melatonin from the pineal regulates the 24-hour (diurnal) rhythm.
- Iodine deficiency causes goitre; hypothyroidism in pregnancy causes cretinism.
- Exophthalmic goitre (Graves’ disease) is a form of hyperthyroidism.
- PTH is hypercalcemic; thyrocalcitonin lowers blood calcium.
- Thymosins help T-lymphocytes differentiate; the thymus degenerates in old age.
- Adrenal cortex layers, inside out: zona reticularis, fasciculata, glomerulosa.
- Cortisol is the main glucocorticoid; aldosterone is the main mineralocorticoid.
- Addison’s disease: underproduction of adrenal cortex hormones.
- Glucagon (alpha cells) is hyperglycemic; insulin (beta cells) is hypoglycemic.
- ANF from the atrial wall lowers blood pressure; erythropoietin comes from juxtaglomerular cells.
- Protein hormones use second messengers such as cAMP; steroids bind intracellular receptors.
Common Mistakes to Avoid
Watch for these mix-ups when you answer questions on this chapter.
- Saying the posterior pituitary makes oxytocin and vasopressin. They are made in the hypothalamus and only stored and released by the posterior pituitary.
- Mixing up diabetes insipidus and diabetes mellitus. Insipidus is due to ADH; mellitus is due to insulin deficiency or resistance with prolonged hyperglycemia.
- Confusing acromegaly and gigantism. Gigantism is excess GH during growth; acromegaly is excess GH in adults.
- Swapping PTH and TCT. PTH raises blood calcium; thyrocalcitonin lowers it.
- Linking cretinism to adults. NCERT links it to hypothyroidism during pregnancy affecting the growing baby.
- Getting the adrenal cortex layers in the wrong order. Glomerulosa is outer, fasciculata middle and reticularis inner.
- Saying the adrenal cortex makes adrenaline. Adrenaline and noradrenaline come from the adrenal medulla.
- Swapping islet cells. Alpha cells make glucagon; beta cells make insulin.
- Saying steroid hormones use cAMP. Steroid hormones bind intracellular receptors and act on genes; second messengers are used by hormones with membrane-bound receptors.
- Thinking the pancreas is only endocrine. It is a composite gland, both exocrine and endocrine.
Chemical Coordination and Integration Notes PDF and Related Pages
Download the AglaSem notes for Chemical Coordination and Integration (key notes and important questions with answers) free: View PDF
- All chapters: NEET Biology notes
- Full topic list: NEET syllabus
- Practice: NEET question papers
- Source text: NCERT Chapter 19 (NCERT, Class 11 Biology)
NEET Biology Notes: All Chapters
Botany
- The Living World
- Biological Classification
- Plant Kingdom
- Cell: The Unit of Life
- Plant Growth and Development
- Anatomy of Flowering Plants
- Cell Cycle and Cell Division
- Respiration in Plants
- Photosynthesis in Higher Plants
- Morphology of Flowering Plants
- Principles of Inheritance and Variation
- Microbes in Human Welfare
- Sexual Reproduction in Flowering Plants
- Molecular Basis of Inheritance
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
Zoology
- Animal Kingdom
- Biomolecules
- Breathing and Exchange of Gases
- Excretory Products and their Elimination
- Body Fluids and Circulation
- Structural Organisation in Animals
- Locomotion and Movement
- Reproductive Health
- Chemical Coordination and Integration
- Neural Control and Coordination
- Evolution
- Human Health and Disease
- Human Reproduction
- Biotechnology and its Applications
- Biotechnology: Principles and Processes
All chapters with their notes PDFs are on the NEET Biology notes page.
Chemical Coordination and Integration NEET Notes FAQs
Which NCERT chapter is Chemical Coordination and Integration?
It is Chapter 19 of the NCERT Class 11 Biology textbook (rationalised edition), the last chapter of Unit 5, Human Physiology, after Neural Control and Coordination (Chapter 18).
Is Chemical Coordination and Integration in the NEET 2027 syllabus?
It is in the latest NEET UG syllabus (2026, released by NMC on 22 December 2025) as ‘Chemical coordination and regulation’ under Unit 5, Human Physiology. NMC is expected to release the 2027 syllabus later; check the syllabus page once it is out.
Which hormones are released by the posterior pituitary?
Oxytocin and vasopressin (ADH). Both are synthesised in the hypothalamus and transported along axons to the neurohypophysis, which stores and releases them.
What is the difference between how insulin and steroid hormones act?
Insulin is a peptide hormone that binds membrane-bound receptors and works through second messengers without entering the cell. Steroid hormones bind intracellular, mostly nuclear, receptors and regulate gene expression.
Are these notes enough for NEET questions on hormones?
No. Read NCERT Chapter 19 line by line first, because NEET Biology questions closely follow the NCERT textbooks. Use these notes and the PDF for quick revision, then practise previous year questions.