NCERT Solutions for Class 11 Biology Chapter 22 - Chemical Coordination and Integration

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“Chemical Coordination and Integration” chapter of Biology Class 11 covers the human endocrine system (thyroid, pancreas, hypothalamus, adrenal, pituitary, parathyroid); endocrine glands and hormones, Addison’s disease, mechanism of hormone action, hypo and hyperactivity and related disorders; the role of hormones as messengers and regulators, and much more.

Question 1:

Define the following—

  1. Exocrine glands.
  2. Endocrine glands.
  3. Hormone.
  1. Exocrine glands. These are the glands with ducts. The secretions of exocrine glands are carried by ducts to a particular organ for some metabolic activity e.g. salivary glands, liver etc.
  2. Endocrine glands. These are ductless glands. These glands have no ducts and their secretions get absorbed into the immediate surrounding blood circulation to reach the specific organs to initiate a particular metabolic change. Endocrine glands secrete chemicals called hormones.
  3. Hormone. A hormone is a non nutrient chemical which acts as an intercelluclar messenger and is produced in trace amounts. The term hormone was introduced by Starling in 1905. The word ‘hormone’ is derived from a Greek word meaning ‘I excite or arouse’.
Question 2:

Diagrammatically indicate the location of various endocrine glands in our body.


Endocrine glands of human body.

Various endocrine glands of human beings.
(Testes and ovaries both are shown for convenience

Question 3:

List the hormones secreted by the following :

  1. Hypothalamus
  2. Pituitary
  3. Thyroid
  4. Parathyroid
  5. Adrenal
  6. Pancreas
  7. Testis
  8. Ovary
  9. Atrium
  10. Kidney
  11. G–I tract
  1. Hormones of Hypothalamus.
    1. Thyrotropin releasing hormone (TRH)
    2. Growth hormone releasing hormone (GHRH)
    3. Growth hormone inhibiting hormone (GHIH)
    4. Gonadotropin releasing hormone (GnRH)
    5. Prolactin releasing hormone (PRH)
    6. Prolactin inhibiting hormone (PIH)
    7. Adrenocorticotropic releasing hor-mone (CRH)
    8. Melanocyte stimulating hormone releasing hormone (MRH)
    9. Melanocyte stimulating hormone inhibiting hormone (MIH)
  2. Hormones of Pituitary
    1. Adrenocorticotropic hormone (ACTH)
    2. Thyroid stimulating hormone (TSH)
    3. Follicle stimulating hormone (FSH)
    4. Luteinizing hormone (LH)
    5. Interstitial cells stimulating hormone (ICSH)
    6. Prolactin or Luteotropic hormone (LTH)
    7. Growth hormone (GH)
    8. Melanocyte stimulating hormone (MSH)
    9. Oxytocin
    10. Vasopressin or Anti diuretic hor-mone (ADH).
  3. Hormones of Thyroid
    1. Triiodothyronine (T3)
    2. Tetraiodothyromine (T4) or thyroxine.
    3. Calcitonin
  4. Hormones of Parathyroid
    1. Parathyroid hormone
  5. Hormones of Adrenal
    1. Mineralocorticoids : (Aldosterone mainly)
    2. Glucocorticoids (cortisol mainly cor-ticosterone cortisone)
    3. Gonadocorticoids androgens estrogens
    4. Adrenaline
    5. Noradrenaline.
  6. Hormones of Pancreas
    1. Insulin
    2. Glucagon
  7. Hormones of Testis
    1. Androgens (testosterone)
  8. Hormones of Ovary
    1. Estrogen
    2. Progesterone
  9. Hormones of Thymus
    1. Thymosin
  10. Hormones of Atrium
    1. Atrial Natriuretic factor (ANF)
  11. Hormones of Kidney
    1. Erythropoietin.
  12. Hormones of G–I tract
    1. Gastrin
    2. Secretin
    3. Enterogasterone
    4. Cholecystokinin (CCK)
    5. Gastric Inhibitory Peptide (GIP)
Question 4:

Fill in the blanks.

Hormones       Target gland
(a) Hypothalamic hormones       ...............
(b) Thyrotropin (TSH)       ...............
(c) Corticotrophin (ACTH)       ...............
(d) Gonadotrophins (LH, FSH)       ...............
(e) Melanotrophin (MSH)       ...............

  1. Pituitary Gland
  2. Thyroid Gland
  3. Adrenal Cortex
  4. Gonads
  5. Melanocytes of skin.
Question 5:

Write short notes on the functions of the following hormones.

  1. Parathyroid hormone (PTH)
  2. Thyroid hormone
  3. Thymosins
  4. Androgens
  5. Estrogens
  6. Insulin and Glucagon.
  1. Parathyroid hormone (PTH). PTH increases Ca2+ levels in the blood. It acts on bones and stimulates the process of bone resorption by deminera-lisation. PTH also stimulates reabsorption of Ca2+ by the renal tubules and increases Ca2+ absorption from digested food.
  2. Thyroid hormone. They play an important role in the regulation of basal metabolic rate. Thyroid hormone also support the process of red blood cell formation. These control the metabolism of carbohydrates, proteins & fats. They also influence water and electrolyte balance of the body.
  3. Thymosins. Thymosins play a major role in the development of the immune system by controlling the differentiation of T- lymphocytes that play a role in cell mediated immunity and also promoting the production of antibodies to provide humoral immunity.
  4. Androgens. Androgens regulate the development, maturation and functions of male accessory sex organs like epididymis, vas deferens, seminal vesicles, prostate gland and urethra. These hormones stimulate, muscular growth, growth of facial and axillary hair, aggressive ness, low pitch of voice etc. They also play a stimulatory role in the process of spermatogenesis (formation of spermatozoa) and act on the central nervous system and influence male sexual behaviour. Androgens also produce anabolic effects on protein and carbohydrate metabolism.
  5. Estrogens.
    1. Stimulation of growth and activities of female secondary sex organs.
    2. Development of growing ovarian follicles.
    3. Appearance of female secondary sexual characters like high pitched voice, mammary gland development.
    4. Regulation of female sexual behaviour.
  6. Insulin and Glucagon.

Insulin is a peptide hormone and plays a major role in regulation of glucose homeostasis. It acts on hepatocytes and adipocytes and enhances cellular glucose uptake and utilisation. As a result, there is a rapid movement of glucose from blood to hepatocytes and adipocytes resulting in decreased blood glucose levels, hypoglycemia.
Insulin also stimulates glycogenesis i.e. the conversion of glucose to glycogen in target cells.
Glucagon is a peptide hormone and plays an important role in maintaining the normal blood glucose levels. It acts mainly on the liver cells (Hepatocytes) and stimulates glycogenolysis (break down of glycogen) resulting in increased blood sugar. In addition, this hormone stimulates the process of gluconeogenesis. It reduces cellular glucose uptake and utilisation. It is a hyperglycemic hormone.

Question 6:

Give example(s) of :—

  1. Hyperglycemic hormone and hypo- glycemic hormone.
  2. Hypercalcemic hormone.
  3. Gonadotrophic hormone.
  4. Progestational hormone.
  5. Blood pressure lowering hormone.
  6. Androgens and estrogens.
  1. Glucagon and Insulin.
  2. Parathyroid hormone, (PTH) increases
  3. LH and FSH. Ca++ level. Thyrocalcitoxin regulates calcium level
  4. Progesterone
  5. ANF—Atrial Natriuretic Hormone
  6. Testosterone and β-estradial
Question 7:

Which hormonal deficiency is responsible for the following ?

  1. Diabetes mellitus.
  2. Goitre.
  3. Cretinism.
  1. Insulin
  2. Thyroid hormone, thyroxine
  3. Deficiency of thyroid hormone, thyroxine, from childhood.
Question 8:

Briefly mention the mechanism of action of hormone FSH.


Follicle stimulating hormone acts by the action through extracellular receptors. The binding of the hormone with its specific receptor present over the cell surface activates an enzyme called adenylate cyclase. This enzyme converts ATP into cAMP i.e. Adensine triphosphate into cyclic adenosine monophosphate. The cAMP is called the second messenger and carries out various biochemical responses in the cell by activating the existing enzyme system in the cell.
The biochemical responses then lead to physiological responses like ovarian growth.

Question 9:

Match the following

  1. T4
  2. PTH
  3. GnRH
  4. LH

1. (b), 2. (d), 3. (a), 4. (c)