NEET Important Chapter - Chemical Coordination and Integration

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

Human Endocrine Glands, Their hormones and Function

Hormones Secreted by Kidneys, Heart and GI-Tract

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.

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

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?

Ans:

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.

Conclusion

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.