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NEET 2022 | Class 12

NEET Important Chapter - Chemical Coordination and Integration

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NEET Notes and Important Questions on Chemical Coordination and Integration

NEET Notes and Important Questions on Chemical Coordination and Integration

Last updated date: 16th Apr 2024
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NEET 2022 is approaching and with very little time in hand, it is important that all NEET aspirants buckle up and make the best use of available resources. This article caters to all NEET aspirants and contains important but short and crisp notes to help you appear for the exam confidently. It contains notes on vital topics, concepts, practice questions, sample questions, and solved previous year questions related to the chapter Chemical Coordination and Integration.

The article will help you clear your doubts and strengthen your basics concerning important concepts of the chapter, such as different types of endocrine glands, hormones secreted by them, their function, etc. Along with this, it contains FAQs regarding the NEET exam. Read through to know more.

Important Topics of Chemical Coordination and Integration

  • Endocrine System

  • Classification of hormones

  • Human Endocrine Glands

  • Hormones - Heart, Kidney, GIT

  • Hormones and Hormonal Disorders

  • Mechanism of Hormone action

Important Concepts

Endocrine Gland

  • Endocrine glands lack ducts. Thus, they are referred to as ductless glands. Their secretions are absorbed into the immediate surrounding blood circulation, allowing them to reach certain organs and trigger a metabolic change.

  • Hormones are non-nutrient molecules produced in trace amounts that operate as intercellular messengers.

  • The holocrine glands are endocrine glands that solely release hormones (e.g., thyroid, parathyroids, adrenals, pituitary gland).

  • The heterocrine glands are glands that have two functions (hormone secretion and certain additional functions) (e.g., pancreas, testes, ovaries, etc).

Classification of Hormones Based on Their Chemical Nature


Amino acid Derivative hormone

Epinephrine, Norepinephrine, Melatonin, Serotonin.


Peptide Hormones

Antidiuretic hormone (ADH), Oxytocin


Protein hormones

Insulin, Glucagon, Pituitary hormones, Thyrocalcitonin, etc.



Thyroid hormones


Steroid hormones

Cortisol, Testosterone, Oestrogen, Progesterone.

Human Endocrine Glands, Their hormones and Function

Name of Gland

Hormones Secreted



  • Releasing hormones- GnRH. Adrenocorticotropic Releasing hormone (ARH), Thyrotropin Releasing hormone (TRH), Growth Hormone Releasing Hormone (GHRH), Prolactin Releasing hormone (PRH), MSH Releasing Hormone

  • Inhibiting hormones- Somatostatin, Prolactin Inhibitory Hormone, MSH Inhibitory Hormone

It produces neurohormones which regulate the synthesis and secretion of pituitary hormones.

Pituitary Gland

  • Anterior Pituitary- Prolactin, Growth hormone, Thyroid-stimulating hormone (TSH), Adrenocorticotropic hormone (ACTH), Gonadotrophic hormone, Luteinizing hormone.

  • Posterior Pituitary- Oxytocin, Antidiuretic hormone.

It secretes a number of hormones which regulate the working of other endocrine glands.

Pineal Gland

Melatonin (sleep hormone)

  • Promotes sleep

  • Produces circadian rhythms, lightens skin colour in certain animals 

  • Inhibitory factor for sexual maturation in mammals.

Thyroid Gland

Thyroxine (tetraiodo-thyroninre or T4), Tri-iodothyronine (T3), Thyrocalcitonin

Parathyroid Gland

Parathyroid hormone

  • Regulates calcium and phosphate balance between blood and other tissues.

  • Inhibits collagen synthesis



It plays a major role in the development of the immune system.

Adrenal Gland

  • Adrenal cortex- Corticoids, i.e., Mineralocorticoids- Eg., Aldosterone, Glucocorticoids- Eg., Cortisol, Gonadocorticoids- Eg., androgens, oestrogens

  • Adrenal medulla- Epinephrine (adrenaline)  and Norepinephrine (noradrenaline)

  • Regulates sodium content of the body

  • Stimulate gluconeogenesis

  • Lipolysis, Proteolysis

  • Maintain cardio-vascular system, kidney functions.

  • Immunosuppressive


  • Glucagon

  • Insulin

  • Glucagon stimulates the liver to convert stored glycogen into glucose.

  • In the liver and muscles, insulin transforms glucose to glycogen.

Testis (male)


  • It stimulates the growth and development of the male secondary sexual characters, male sex organs like  seminal vesicles, prostate and penis.

  • This hormone is involved in the growth of many body tissues. For example; bones and muscles.

Ovary (female)

Oestrogen, Progesterone

  • Oestrogen stimulates the development of the female secondary sex characteristics during puberty.

  • Oestrogen stimulates maturation of ova.

  • Progesterone stimulates further development of the uterine epithelium and mammary glands.

  • Progesterone maintains pregnancy.

Hormones Secreted by Kidneys, Heart and GI-Tract






Stimulates erythropoiesis


Atrial natriuretic factor

This hormone decreases blood pressure by causing dilation of blood vessels.

Gastro-Intestinal Tract

  • Gastrin

  • Secretin

  • Cholecystokinin (CCK)

  • Gastric inhibitory peptide (GIP)

  • Gastrin stimulates the secretion of hydrochloric acid and pepsinogen.

  • Secretin stimulates the exocrine pancreas to secrete water and bicarbonate ions.

  • CCk acts on both pancreas and gall bladder and stimulates the secretion of pancreatic enzymes and bile juice respectively.

Mechanism of Hormone Action

  • Hormones produce their effects on target tissues by binding to specific proteins called hormone receptors located in the target tissues only.

  • Hormone receptors found on the cell membrane of target cells are known as membrane-bound receptors, while receptors found inside the target cell, predominantly nuclear receptors, are known as intracellular receptors (present in the nucleus). 

  • The formation of a hormone-receptor complex occurs when a hormone binds to its receptor.

  • The development of a hormone-receptor complex causes biochemical changes in the target tissue.

  • Hormones control the metabolism of target tissues and, as a result, physiological processes.

Feedback Mechanism

Figure: Image Showing the Feedback Mechanism

Disorders of the Glands

1. Exophthalmic Goitre or Grave's Disease

It is a thyroid enlargement disease in which the thyroid secretes an excessive amount of thyroid hormone. It is characterised by exophthalmia, loss of weight, a slight rise in body temperature and rapid heartbeat.

2. Cretinism

It is caused by a deficiency of thyroid hormone in infants. Cretin slows physical growth and slower cerebral development, as well as a lower metabolic rate.

3. Simple Goitre

It is caused by the deficiency of iodine in diet as iodine is needed for the synthesis of thyroid hormone. In this disorder, the thyroid gland is enlarged.

4. Hashimoto's Disease

In this disease, all aspects of thyroid function are impaired. It is an autoimmune disorder in which autoimmunity destroys the thyroid gland.

5. Addison's Disease

It is caused by a deficit of mineralocorticoids and glucocorticoids. It shows symptoms like low blood sugar, low ions, nausea, and vomiting.

6. Cushing's Syndrome

Cortisol overproduction is the cause of this disease. Some of the symptoms include low blood sugar, low ions, nausea, and vomiting.

7. Gigantism

It is caused by excess secretion of growth hormone at an early age. It is recognised by a big, well-proportioned body.

8. Acromegaly

It is caused by a surplus of a growth hormone once one has achieved adult size. It's marked by a disproportionate increase in the size of the bones in the face, hands, and feet.

9. Diabetes Mellitus (Hyperglycemia)

It is caused due to failure of beta-cells to produce an adequate amount of insulin.

10. Hypoglycemia

When the blood glucose level falls below normal, it is called hypoglycemia.

Difference Between Diabetes Mellitus and Diabetes Insipidus

Diabetes Mellitus 

Diabetes Insipidus 

I. It is due to a deficiency of insulin.

I. It is due to a deficiency of ADH.

2. Blood sugar levels rise, and glucose is detected in the urine.

2. The blood glucose level is normal, and no glucose is detected in the urine.

3. There is a high level of blood cholesterol and the synthesis of ketone bodies.

3. There is no such phenomenon.

4. Excessive urine production, thirst, and overeating are all indications of this condition.

4. Large amounts of urine are excreted, as well as thirst and dehydration.

Solved Examples from the Chapter

1. What is the name of the steroid that regulates inflammatory responses? Identify its source as well as its other functions.

Ans: Glucocorticoids. The adrenal cortex produces these hormones. They cause gluconeogenesis, proteolysis, and lipolysis, as well as prevent amino acid absorption and utilisation in cells.

Key Point to Remember: Glucocorticoids work with immune cells.

2. Glucose and ketone bodies were found in higher concentrations in a urine sample. Based on your observation, answer the questions below.

a) Identify the hormone and glands that are linked to this disorder.

b) Which cells are affected by these hormones?

c) Give the name of the condition. How can it be corrected?


a. Insulin is a hormone, and the pancreas is the gland that produces it.

b. It affects the β--cells of the islets of Langerhans in the pancreas.

c. Diabetes mellitus is caused by long-term hyperglycemia, which is related to glucose loss through urine and the accumulation of toxic chemicals known as ketone bodies. Diabetic patients can be successfully treated with insulin therapy.

Solved Problems of Previous Year Questions

1. The hypothalamic hormone GnRH, which is required for reproduction, acts on

  1. Anterior pituitary gland and stimulates secretion of LH and oxytocin.

  2. Posterior pituitary gland and stimulates secretion of LH and relaxin 

  3. Posterior pituitary gland and stimulates the secretion of oxytocin and FSH

  4. Anterior pituitary gland and stimulates the secretion of LH and FSH.

Ans: d. anterior pituitary gland and stimulates the secretion of LH and FSH.

Gonadotropin-releasing hormone (GnRH) is a hormone that releases gonadotropins. GnRH induces the secretion of gonadotropins such as LH (luteinizing hormone) and FSH (follicle stimulating hormone) by acting on the anterior pituitary (follicle-stimulating hormone). LH and FSH are hormones that govern male and female gonad reproductive activity.

Trick to Remember:

Hypothalamus —--> GnRH —----> Anterior pituitary gland —---> LH and FSH

2. In adults, hypersecretion of growth hormone does not result in an increase in height because

  1. Growth hormone becomes inactive in adults.

  2. Bones lose their sensitivity to growth hormone in adults.

  3. Epiphyseal plates close after adolescence.

  4. After birth, muscle fibres do not expand in size.

Ans: c. epiphyseal plates close after adolescence.

At the end of long bones, epiphyseal plates can be found. It's a hyaline cartilage also known as growth plate, a plate that allows for new bone formation. It is present in children and adolescents, but in adults, it is replaced by the epiphyseal line. Epiphyseal closure, or growth plate fusion, is the name given to this process. Acromegaly is a condition characterised by severe deformity in adults due to GH hypersecretion.

Trick to Remember:

Hypersecretion of Growth Hormone in Adults - Acromegaly

Hypersecretion of Growth Hormone in Children - Gigantism

Practice Questions

1. The alpha cells of the pancreas produce__________.

  1. Relaxin

  2. Calcitonin

  3. Insulin

  4. Glucagon

Ans: d. Glucagon

The alpha cells present in the pancreas produce glucagon that releases glucose by acting on glycogen, which is stored in the liver.

Key Point to Remember:

Islets of Langherhans -

  • α-cells- Glucagon

  • β-cells- Insulin

  • δ-cells- Somatostatin

  • F-cells- Pancreatic polypeptide

2. Choose the hormone that controls carbohydrate, protein, and lipid metabolism in the opposite way as insulin does

  1. Cortisol

  2. Epinephrine

  3. Thyroxine

  4. Glucagon

Ans: c. Thyroxine

The hormone that controls carbohydrate, protein, and lipid metabolism is the thyroxine hormone which is secreted by the thyroid gland.

Key Point to Remember: Thyroxine hormone is responsible for metabolism of the body.


This article has been created keeping the NEET aspirants in focus. By going through this, students will be able to easily grasp all of the major concepts and read clear explanations of difficult topics. It is an ideal source for thorough preparation and quick revision. It covers key ideas, concepts, and problems from NCERT Biology books, previous year's NEET question papers as well as NEET sample papers. Make sure to test your understanding by visiting our website and attempting the NEET practice questions on this chapter.

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FAQs on NEET Important Chapter - Chemical Coordination and Integration


1. What is the minimum age requirement for NEET?

Candidates must be 17 years old at the time of admission or by December 31st of the previous year.

2. Is it necessary to have good marks in 12th grade to apply for NEET?

When applying for MBBS admission, the candidate needs to meet certain eligibility criteria laid down. However, in order to appear for the NEET examination, a candidate must have obtained the required percentage in PCB in 12th grade, which is 50 percent for UR, 40 percent for OBC/SC/ST, and 45 percent for PWD.

3. What are the names of the chapters that hold more weightage in NEET?

Human Physiology, Biological Classification, Molecular Basis of Inheritance, and Biomolecules had the highest weightage from the previous year's NEET paper analysis. However, it is highly recommended that you study the other chapters well enough to be prepared for any question that may appear in the exam.