NCERT Solutions for Class 11 Biology Chapter 19 – Chemical Coordination and Integration

NCERT Solutions for class 11 Chapter 19 Chemical Coordination and Integration: The chapter on Chemical Coordination and Integration is important for students approaching the home exams. This article introduces NCERT solutions designed to help students explain the concepts of further learning and how to write to get good grades on exams. The solutions are presented in very simple language for ease of understanding.

NCERT CBSE Chapter 19 Chemical Coordination and Integration of Class 11 explains that there are special chemicals that act like hormones and release chemicals which regulate the metabolism, growth, and development of our organs and endocrine glands. The human endocrine system, mechanism of action of hormones, and their role are important for various functions of the body. Revise the basic concepts of Chemical Coordination and Integration for quick revision and class notes.

Q1: Define the Following:

• (a) Exocrine gland
• (b) Endocrine gland
• (c) Hormone

Answer:

(a) Exocrine gland

An exocrine gland secretes its products, such as enzymes, hormones, or mucous, into ducts, that carry the secretions to specific target areas.Examples of exocrine glands include sweat glands, salivary glands, sebaceous glands (oil glands), and mammary glands.

(b) Endocrine gland

An endocrine gland secrets hormones directly into the bloodstream, through which it is  transported to the target cell or organ throughout the body. Examples of endocrine glands in include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, gonads (ovaries and testes), pineal gland.

(c) Hormone

Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts either by the glands or specialized cells in the body. They regulate various physiological processes and bodily functions.

Q2: Diagrammatically indicates the location of the various endocrine glands in our body.

Answer:

The location of the various endocrine glands in our body is shown in the diagram given below:

Endocrine system

Q3: 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

Answer:

(a) Hypothalamus

The hormones secreted by hypothalamus are:

Releasing Hormones(stimulate secretion of pituitary gland)	Adrenocorticotropin-releasing hormone (ARH) Thyrotropin-releasing hormone (TRH) Follicle-stimulating hormone-releasing hormone (FSH – RH) Luteinising hormone-releasing hormone (LH-RH) Prolactin-releasing hormone (PRH) Growth hormone-releasing hormone Melanocyte-stimulating hormone-releasing hormone
Inhibiting hormone (inhibit secretion of pituitary gland)	Growth inhibiting hormone Prolactin inhibiting hormone Melanocyte-stimulating hormone-inhibiting hormone

(b) Pituitary gland

The hormones secreted by Pituitary gland are:

Anterior lobe of pituitary gland	Follicle-stimulating hormone Luteinizing hormone  Thyroid-stimulating hormone Adrenocorticotropic hormone Somatotrophic or Growth hormone Prolactin hormone or Luteotropic hormone.
Middle lobe of pituitary gland	Melanocyte stimulating hormone.
Posterior lobe of pituitary gland	Oxytocin Vasopressin or antidiuretic hormone.

(c) Thyroid gland

The hormones secreted by thyroid gland are:

1. Tri-iodothyronine (T3)
2. Tetraiodothyronine/Thyroxine (T4)
3. Calcitonin

(d) Para thyroid gland

The hormone secreted by para thyroid gland is Parathormone (PTH).

(e) Adrenal gland

The hormones secreted by adrenal gland are:

Hormone secreted by adrenal cortex	Glucocorticoids, e.g., cortisol Mineralocorticoids, e.g., aldosterone Sex corticoids e.g. testosterone.
Hormone secreted by adrenal medulla	Epinephrine (adrenaline) Nor-epinephrine (nor-adrenaline)

(f) Pancreas gland

The hormones secreted by pancreas gland are:

1. Glucagon
2. Insulin
3. Somatostatin

(g) Testis 

The hormones secreted by testis are

1. Testosterone
2. Androsterone

(h) Ovary

The hormones secreted by ovary are:

1. Oestrogen
2. Progesterone
3. Relaxin 

(i) Thymus

The hormone secreted by thymus is Thymosin.

(j) Atrium

The hormone secreted by atrium is Atrial Natriuretic Factor (ANF).

(k) Kidney

The hormone secreted by Kidney is erythropoietin.

(l) G-I Tract

The hormones secreted by G-I tract are:

1. Gastrin
2. Secretin
3. Cholecystokinin(CCK)
4. Gastric inhibitory peptide (GIP)

Q4: Fill in the blanks:

Hormones Target Gland

• (a) Hypothalamic hormones __________________
• (b) Thyrotrophin (TSH) __________________
• (c) Corticotrophin (ACTH) __________________
• (d) Gonadotrophins (LH, FSH) __________________
• (e) Melanotrophin (MSH) __________________

Answer:

(a) Hypothalamic hormones – Pituitary gland

(b) Thyrotrophin (TSH) – Thyroid gland

(c) Corticotrophin (ACTH) – Adrenal cortex

(d) Gonadotrophins (LH, FSH) –  Gonads, Testis in males and ovaries in females 

(e) Melanotrophin (MSH) – Melanocyte cells present in the dermis of skin.

Q5: Write Short Notes on the Functions of the following Hormones

• (a) Parathyroid hormone (PTH)
• (b) Thyroid hormones
• (c) Thymosins
• (d) Androgens
• (e) Estrogens
• (f) Insulin and Glucagon

Answer:

(a) Parathyroid hormone

It is a peptide hormone secreted by the parathyroid gland that is situated at the back of the thyroid gland. It’s secretion is regulated by the circulating level of calcium ions. PTH is a hypercalcemic hormone, i.e., it increases the blood calcium levels by following processes: stimulating the process of bone resorption, stimulating reabsorption of calcium by the renal tubules and increases calcium absorption from the digested food. 

(b) Thyroid hormone 

Thyroid hormone performs the following functions:

• It regulates the basal metabolic rate. 
• It supports the process of the formation of red blood cells.
• It regulates the metabolism of some biomolecules, e.g. carbohydrates, proteins and fats.
• It helps in osmoregulation; maintains the water and electrolyte balance.
• It also secretes thyrocalcitonin (TCT) hormone which regulates the blood calcium level.

(c) Thymosin

• It plays an important role in activating immune response. It provides cellular immunity through differentiation of T-lymphocytes and humoral immunity through production of antibodies.

(d) Androgens 

• Androgens play an important role in the development and maturation of the male sex organs like epididymis, vas deferens, prostate gland seminal vesicles and urethra.
• They stimulate muscular growth, growth of facial and axillary hair, aggressiveness, low pitch of voice.
• They also play a significant role in spermatogenesis and influence male sexual behaviour.

(e) Estrogen

• It stimulates the growth and development of the female secondary sex organs and ovarian follicles.
• It play a major role in the appearance of female secondary sex characters (e.g., high pitch of voice, etc.)
• It facilitates the development of mammary gland.
• It also regulates the female sexual behaviour.

(f) Insulin and glucagon

Insulin 

• It regulates the blood glucose level.
• It enhances cellular glucose uptake and utilisation by acting mainly on hepatocytes and adipocytes.
• It also stimulates conversion of glucose to glycogen (glycogenesis) in the target cells.

Glucagon

•  It maintains the normal blood glucose level.
• It stimulates glycogenolysis resulting in increased blood sugar level( hyperglycemia) by acting on liver cells.
• It reduces the uptake of cellular glucose and it’s utilisation.

Q6: 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

Answer:

(a) Hyperglycemic hormone- Insulin

     Hypoglycemic hormone- Glucagon

(b) Hypercalcemic hormone- Parathormone hormone (PTH)

(c) Gonadotropin hormone- Follicle-stimulating hormone (FSH) and luteinising hormone (LH)

(d) Progestational hormone- Progesterone

(e) Blood pressure lowering hormone- Atrial natriuretic factor (ANF)

(f) Androgen- Testosterone and androsterone

    Estrogen- Estradiol

Q7: Which Hormonal Deficiency is Responsible for the Following?

• (a) Diabetes mellitus
• (b) Goitre
• (c) Cretinism

Answer:

(a) Diabetes mellitus

Diabetes mellitus is characterised by high blood glucose level that is caused by deficiency of insulin hormone.

(b) Goitre

Goitre is characterised by enlargement of thyroid gland due to deficiency of thyroxin hormone.

(c) Cretinism

Cretinism is characterised by stunted growth in the children caused due to deficiency of thyroid hormone.

Q8: Briefly Mention the Mechanism of Action of FSH.

Answer:

FSH is a key regulator of reproductive function in both males and females. It regulates the growth and development of ovarian follicles, facilitates estrogen production, promotes spermatogenesis in males.

Mechanism of Action of FSH

Follicle-stimulating hormone (FSH) is a glycoprotein polypeptide hormone. Being a peptide it is insoluble in lipids,so it does not enter the target cell, and generate second messengers that regulate cellular metabolism.

(1) Formation of hormone – receptor complex –  FSH molecules binds to the receptor protein present on the surface of the cell.

(2) Formation of cyclic AMP – The hormone activates the adenyl cyclase enzyme, that converts ATP to cyclic AMP. Cyclic AMP acts as a second messenger.

(3)  Production of Estrogen – Second messenger stimulates the follicular cells present at the membrane of granulose to produce estrogens.

Q9: Match the Following:

Column I	Column II
(a) T4	(i) Hypothalamus
(b) PTH	(ii) Thyroid
(c) GnRH	(iii) Pituitary
(d) LH	(iv) Parathyroid

Answer:

Column I	Column II
(a) T 4	(ii) Thyroid
(b) PTH	(iv) Parathyroid
(c) GnRH	(i) Hypothalamus
(d) LH	(iii) Pituitary