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NCERT Solutions Class 11 Biology Chapter 19 - Chemical Coordination and Integration
NCERT Solutions for Class 11 Biology Chapter 19 (Chemical Coordination and Integration) explain how hormones regulate different activities of the human body. Unlike the nervous system, which sends signals quickly through nerve cells, the endocrine system uses hormones to control processes such as growth, metabolism, reproduction, and the body's response to stress. This chapter covers the major endocrine glands, the hormones they release, and their functions.
NCERT Solutions for Class 11 Biology Chapter 19 by ALLEN provide clear explanations of the human endocrine system and the role of hormones released by glands such as the pituitary, thyroid, adrenal glands, and pancreas. Students can learn about hormone action, feedback regulation, and disorders caused by hormonal imbalances, including diabetes mellitus and goitre. These solutions also explain how hormones act through receptors on or inside target cells. They help students revise NCERT topics, understand textbook questions, and prepare for school exams and NEET.
1.0Class 11 Biology Chapter 19 Chemical Coordination and Integration: Key Concepts
Class 11 Biology Chapter 19 explains how hormones help coordinate and regulate different functions of the human body. The chapter covers the major endocrine glands, the hormones they release, their functions, and how hormones act on target cells.
- Endocrine Glands and Hormones: Understand how hormones act as chemical messengers and regulate body functions in small amounts.
- Human Endocrine System: Learn about the major endocrine glands, their locations, the hormones they release, and their functions.
- Hypothalamus: Study how releasing and inhibiting hormones regulate the secretion of hormones from the pituitary gland.
- Pituitary Gland: Understand the functions of the anterior and posterior pituitary and their role in regulating growth, reproduction, and other body activities.
- Pineal Gland: Learn about melatonin and its role in regulating the body's daily rhythms.
- Thyroid Gland: Study the functions of thyroid hormones, T₃ and T₄, and the role of iodine in their production and metabolism.
- Adrenal Gland: Understand how the adrenal medulla releases adrenaline and noradrenaline during stress and how hormones from the adrenal cortex regulate different body functions.
- Pancreas: Learn about its endocrine and exocrine functions and how insulin and glucagon regulate blood glucose levels.
- Hormones from Other Organs: Study the roles of hormones released by the heart, kidneys, and gastrointestinal tract, including ANF, erythropoietin, gastrin, and secretin.
- Mechanism of Hormone Action: Understand how hormones bind to specific receptors on or inside target cells to produce a response.
- Water-Soluble and Lipid-Soluble Hormones: Learn how water-soluble hormones use second messengers, such as cAMP, IP₃, and Ca²⁺, while lipid-soluble hormones can enter cells and act through intracellular receptors.
2.0Detailed NCERT Textbook Solutions : Class 11 Biology Chapter 19
- Define the following: (a) Exocrine gland, (b) Endocrine gland, (c) Hormone.
Ans.
(a) Exocrine gland is a gland that pours its secretion on the surface or into a particular region by means of ducts for performing a metabolic activity, e.g., sebaceous glands, sweat glands, salivary glands and intestinal glands. (b) Endocrine glands lack ducts and are hence, called ductless glands. Their secretion are called hormones. (c) The classical definition of hormone as a chemical produced by endocrine glands and released into the blood and transported to a distantly located target organ has current scientific definition as follows: Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts.
- Diagrammatically indicate the location of the various endocrine glands in our body.
Ans.
- List the hormones secreted by the following: (a) Hypothalamus (b) Pituitary (c) Thyroid (d) Parathyroid (e) Adrenal (f) Pancreas (g) Testis (h) Ovary (i) Thymus (j) Atrium (k) Kidney (l) G-I Tract.
Ans.
(a) Two types of hormones are produced by hypothalamus: releasing hormones (that stimulate secretion of pituitary hormones) and inhibiting hormones (that inhibit secretion of pituitary hormones).
These hormones are:
- Thyrotrophin-releasing hormone
- Adrenocorticotrophin-releasing hormone
- Follicle-stimulating hormone-releasing hormone
- Luteinizing hormone-releasing hormone
- Growth hormone-releasing hormone
- Growth-inhibiting hormone
- Prolactin-releasing hormone
- Prolactin-inhibiting hormone
- Melanocyte-stimulating hormone-releasing hormone
- Melanocyte-stimulating hormone-inhibiting hormone
(b) Different parts of pituitary secrete different hormones. Hormones secreted by anterior lobe of pituitary are:
- Follicle-stimulating hormone
- Luteinizing hormone
- Thyroid-stimulating hormone
- Adrenocorticotrophic hormone
- Somatotrophic or growth hormone
- Prolactin hormone or luteotrophic hormone
Middle (intermediate) lobe of pituitary:
- Melanocyte-stimulating hormone
Posterior lobe of pituitary:
(i) Oxytocin (ii) Vasopressin or antidiuretic hormone
(c) Thyroid secretes 3 hormones:
- Thyroxine or tetraiodothyronine
- Triiodothyronine
- Calcitonin
(d) Parathyroid gland secretes a single hormone called parathormone (PTH) or Collip's hormone.
(e) Adrenal glands have two regions, namely, outer adrenal cortex and inner adrenal medulla. Both these regions secrete different hormones.
Hormones of adrenal cortex are grouped into three categories:
- Glucocorticoids, e.g., cortisol
- Mineralocorticoids, e.g., aldosterone
- Sexcorticoids, e.g., testosterone
Adrenal medulla secretes two hormones:
(i) Epinephrine (adrenaline) (ii) Nor-epinephrine (nor-adrenaline)
(f) Pancreas secretes the following hormones:
- Insulin
- Glucagon
- Somatostatin
(g) Testis secretes androgens such as testosterone.
(h) Ovary secretes:
- Estrogens such as estradiol
- Progesterone
- Relaxin
(i) Thymus secretes thymosin hormone.
(j) Atrium secretes atrial natriuretic factor (ANF).
(k) Kidney secretes:
(i) Renin (ii) Erythropoietin
(l) G.I. tract secretes:
- Gastrin
- Secretin
- Cholecystokinin
- Enterocrinin
- Duocrinin
- Villikinin
- Fill in the blanks: Hormones Target gland (a) Hypothalamic hormones ____ (b) Thyrotrophin (TSH) ____ (c) Corticotrophin(ACH) ____ (d) Gonadotrophins (LH, FSH) ____ (e) Melanotrophin (MSH) ____
Ans.
(a) Pituitary (b) Thyroid (c) Adrenal cortex (d) Gonads -Testes in male and ovaries in female (e) Skin.
- Write short notes on the functions of the following hormones: (a) Parathyroid hormones (PTH) (b) Thyroid hormones (c) Thymosin (d) Androgens (e) Estrogens (f) Insulin and Glucagon.
Ans.
(a) The parathyroid glands secrete a peptide hormone called parathyroid hormone (PTH). The secretion of PTH is regulated by the circulating levels of calcium ions. Parathyroid hormone (PTH) increases the levels in the blood. PTH acts on bones and stimulates the process of bone resorption (dissolution/demineralisation). PTH also stimulates reabsorption of by the renal tubules and increases absorption from the digested food. It is, thus, clear that PTH is a hypercalcemic hormone, i.e., it increases the blood levels. Along with TCT, it plays a significant role in calcium balance in the body.
(b) Thyroid hormones play an important role in the regulation of the basal metabolic rate. These hormones also support the process of red blood cell formation. Thyroid hormones control the metabolism of carbohydrates, proteins and fats. Maintenance of water and electrolyte balance is also influenced by thyroid hormones. Thyroid gland also secretes a protein hormone called thyrocalcitonin (TCT) which regulates the blood calcium levels. (c) Thymosin is secreted by thymus. It accelerates cell division, stimulates the development and differentiation of T-lymphocytes and also hastens attainment of sexual maturity. (d) Androgens regulate the development, maturation and functions of the male accessory sex organs like epididymis, vas deferens, seminal vesicles, prostate gland, urethra etc. These hormones stimulate muscular growth, growth of facial and axillary hair, aggressiveness, low pitch of voice etc. Androgens play a major stimulatory role in the process of spermatogenesis (formation of spermatozoa). Androgens act on the central neural system and influence the male sexual behaviour (libido). These hormones produce anabolic (synthetic) effects on protein and carbohydrate metabolism. (e) Estrogens produce wide ranging actions such as stimulation of growth and activities of female secondary sex organs, development of growing ovarian follicles, appearance of female secondary sex characters (e.g., high pitch of voice, etc.), mammary gland development. Estrogens also regulate female sexual behaviour. Progesterone supports pregnancy. Progesterone also acts on the mammary glands and stimulates the formation of alveoli (sac-like structures which store milk) and milk secretion. (f) Insulin is secreted by the 3-cells of the pancreas. It lowers blood glucose level, and promotes synthesis of proteins and fats. Glucagon is secreted by the a-cells of the pancreas. It increases the level of glucose in the blood.
- Give example(s) of (a) Hyperglycemic hormone and hypoglycemic hormone (b) Hypercalcemic hormone (c) Gonadotrophic hormones (d) Progestational hormone (e) Blood pressure lowering hormone (f) Androgens and estrogens.
Ans.
(a) Glucagon, Insulin (b) Parathormone (PTH) (c) Follicle stimulating hormone (FSH) and Luteinizing hormone (LH) (d) Progesterone (e) Atrial natriuretic factor (f) Testosterone and Estradiol.
- Which hormonal deficiency is responsible for the following : (a) Diabetes meilitus (b) Goitre (c) Cretinism.
Ans.
(a) Insulin (b) Thyroxine and Triiodothyronine (c) Thyroxine and Triiodothyronine.
- Briefly mention the mechanism of action of FSH. Ans. FSH (Follicle stimulating hormone) interacts with membrane bound receptors present on the target cells. Binding of FSH to its receptor leads to the formation of a hormone-receptor complex, which generates second messengers such as cyclic AMP(CAMP). These second messengers regulate cellular metabolism and produce the required physiological response in the target cells.
- Match the following :
Ans. (a) - (ii); (b) - (iv); (c) - (i); (d) - (iii)
3.0NCERT Class 11 Biology – Chapter-Wise Solutions & Explanations
Find chapter-wise NCERT Solutions for Class 11 Biology with answers to all textbook questions. Review each chapter, practise important questions, and prepare for your exams.
4.0Key Features of NCERT Solutions for Class 11 Biology Chapter 19
- Glands, Hormones, and Their Functions: Learn about the major endocrine glands, the hormones they release, and their functions in the human body.
- Mechanism of Hormone Action: Understand how peptide and steroid hormones act on target cells through different signalling mechanisms.
- Endocrine Disorders: Learn the differences between disorders such as cretinism and myxoedema, as well as diabetes mellitus and diabetes insipidus.
- Hypothalamus and Pituitary Gland: Understand how the hypothalamus regulates the pituitary gland through hormonal signals and nerve connections.
- Prepared by ALLEN Expert Faculty: Study clear explanations of endocrine glands, hormone functions, and related disorders based on the NCERT Class 11 Biology syllabus.
- Hormones with Opposing Functions: Learn how insulin and glucagon regulate blood glucose levels and how parathyroid hormone (PTH) and calcitonin help regulate calcium levels.
- Complete NCERT Exercise Solutions: Find answers to NCERT textbook questions to revise Chemical Coordination and Integration and prepare for school exams and NEET.