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Class 11-science NCERT Solutions Biology Chapter 19 - Chemical Coordination And Integration

Chemical Coordination And Integration Exercise 251

Solution 1

  1. Exocrine glands: Glands which release their secretions into ducts which carry them either on the body surface or to specific body organs are called exocrine glands.
  2.  Endocrine glands: Glands which are ductless and release their secretions into the blood and transported to a distantly located target organ are called endocrine glands.
  3.  Hormone: A non-nutrient chemical which acts as an intercellular messenger and produced in trace amounts is called a hormone.

Solution 2






Solution 3


Hormones Secreted

(a)  Hypothalamus

  • Thyrotropin-releasing hormone (TRH)
  • Adrenocorticotropin-releasing hormone (ARH)
  • Follicle-stimulating hormone-releasing hormone (FSH-RH)
  • Luteinising hormone-releasing hormone (LH-RH)
  • Growth hormone-releasing hormone (GH-RH) Somatostatin
  • Prolactin-releasing hormone (PRH)

(b)  Pituitary

  • Adenohypophysis:
    • Growth hormone (GH)
    • Thyroid-stimulating hormone (TSH)
    • Follicle-stimulating hormone (FSH)
    • Luteinising hormone (LH)
    • Adrenocorticotropic hormone (ACTH)
  • Intermediate lobe:
    • Melanocyte-stimulating hormone (MSH)
  • Neurohypophysis:
    • Anti-diuretic hormone (Vasopressin)
    • Oxytocin

(c) Thyroid

  • Thyroxine/tetraiodothyronine (T4)
  • Tri-iodothyronine (T3)
  • Calcitonin

(d)  Parathyroid

  • Parathormone (PTH)

(e)  Adrenal

  • Adrenal cortex:
    • Mineralocorticoids (aldosterone)
    • Glucocorticoids
  • Adrenal medulla:
    • Adrenaline
    • Noradrenaline

(f)  Pancreas

  • Glucagon
  • Insulin
  • Somatostatin

(g)  Testis

  • Testosterone
  • Androsterone

(h)  Ovary

  • Oestrogen
  • Progesterone
  • Relaxin

(i)   Thymus

  • Thymosin

(j)   Atrium

  • Atrial natriuretic factor (ANF)

(k)  Kidney

  • Erythropoietin

(l)   GI Tract

  • Stomach
    • Gastrin
  • Intestine
    • Secretin
    • Cholecystokinin
    • Enterogastrone
    • Enterocrinin
    • Duocrinin
  • Liver
    • Angiotensinogen

Solution 4

(a) Pituitary gland  

(b) Thyroid gland

(c) Adrenal cortex

(d) Testis and ovaries

(e) Pigment cells of the dermis of the skin

Solution 5(a)

Parathyroid hormone (PTH):

  • The parathyroid hormone maintains the calcium levels in the body.
  • It increases the calcium levels of the blood.
  • It stimulates bone resorption which demineralises bones increasing blood calcium levels.
  • It also stimulates calcium absorption by renal tubules and from the digested food.

Solution 5(b)

Thyroid hormones:

 Thyroxine/tetraiodothyronine (T4):

  • It regulates the basal metabolic rate (BMR).
  • It regulates body growth such as ossification of bones and mental development.
  • It controls body weight.
  • It also controls tissue differentiation and metamorphosis of the tadpole larva into an adult frog.
  • It suppresses RBC formation.

 Tri-iodothyronine (T3):

  • It increases the body's oxygen and energy consumption.
  • It increases the heart rate and force of contraction which increases the cardiac output.


  • It regulates calcium and phosphate levels in the blood. 

Solution 5(c)


  • Thymosin stimulates the differentiation of T-lymphocytes and provides cell-mediated immunity.
  • It promotes the production of antibodies to provide humoral immunity.
  • It also stimulates the rate of cell division in kids and hence promotes growth.

Solution 5(d)



  • Testosterone helps in the maturation of sperms.
  • It stimulates the growth and development of the male reproductive system.
  • It stimulates the development of secondary sexual characters such as beard and moustache.
  • It produces anabolic effects on protein and carbohydrate metabolism.


  • It affects the masculinisation of the foetus and child, and maintains or creates masculine traits in adults. 

Solution 5(e)


  • It stimulates the development of ovarian follicles.
  • It stimulates the growth and development of female reproductive organs such as the fallopian tube, uterus and vagina.
  • It increases the sensitivity of the uterus to oxytocin.
  • It decreases the secretion of FSH and increases the secretion of LH.
  • It promotes the development of mammary glands.
  • It also regulates female sexual behaviour. 

Solution 5(f)


  • It plays a major role in the regulation of glucose homeostasis.
  • It acts on hepatocytes and adipocytes.
  • It stimulates the transport of glucose from blood to muscle.
  • It promotes the oxidation of glucose and the conversion of glucose to glycogen, i.e. glycogenesis, resulting in hypoglycaemia.


  • It plays a major role in the maintenance of normal blood glucose levels.
  • It acts on hepatocytes and stimulates the conversion of glycogen into glucose.
  • It also stimulates the process of gluconeogenesis, i.e. the conversion of non-carbohydrate substances such as fats and proteins to glucose.

Solution 6

  1. Hyperglycemic hormone: Glucagon
    Hypoglycemic hormone: Insulin
  2. Hypercalcemic hormone: Parathormone hormone (PTH)
  3. Gonadotropic hormones: Luteinising hormone (LH) and follicle-stimulating hormone (FSH)
  4. Progestational hormone: Progesterone
  5. Blood pressure-lowering hormone: Atrial natriuretic factor (ANF)
  6. Androgens: Testosterone and androsterone
    Oestrogens: β-oestradiol


Solution 7

(a)   Diabetes mellitus: Insufficient secretion of insulin

(b)   Goitre: Insufficient secretion of thyroxine

(c)    Cretinism: Insufficient secretion of thyroxine

Solution 8

  • Follicle-stimulating hormone (FSH) is a glycoprotein polypeptide hormone.
  • It is insoluble in lipid and hence cannot enter the target cell.
  • This hormone binds to the cell surface and activates cellular systems to perform functions.
  • Steps in action of FSH:
    • A molecule of FSH binds on the receptor protein present on the cell surface and forms the hormone–receptor complex.
    • Formation of hormone–receptor complex activates the enzyme adenyl cyclase.
    • Adenyl cyclase converts ATP into cyclic AMP (cAMP) as a second messenger.
    • cAMP activates the follicular cells of membrane granulose to secrete oestrogens.

Solution 9

Column I

Column II

(a)     T4

(ii) Thyroid

(b)     PTH

(iv) Parathyroid

(c)      GnRH

(i) Hypothalamus

(d)     LH

(iii) Pituitary


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