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NCERT Solutions for Class 11 Biology Chapter 22 : Chemical Control and Integration

NCERT Solutions for Class 11 Biology Chapter 22 Chemical Control and Integration will help you to ace the unsolved problems in the Class 11 Science book prescribed by the NCERT for all the schools of CBSE. These NCERT Solutions presents the best alternative and are a very interesting way to learn, which helps to enhance your abilities and help to get ready for CBSE Class 11 exams.

Biology Chapter 22 Chemical Control and Integration Class 11 Notes are prepared by our expert faculties to help you to prepare for your exams in a better way and enhance your score. It provides step-by-step solutions for the questions given in the NCERT textbook as per CBSE Board guidelines and is also prepared according to the exam pattern. In case of any doubt, we have a team of teachers who prove 24 x 7 live doubt solving sessions only for you.

In NCERT Solutions for Class 11 Biology Chapter 22, you will understand about endocrine glands and hormones, human endocrine system, the hypothalamus, the pituitary gland, the pineal gland, thyroid gland, parathyroid gland, thymus, adrenal gland, pancreas, testis, ovary, hormones of heart, kidney and gastrointestinal tract and mechanism of hormone action.

Table of Content

Introduction

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Exercise Questions

Question 1

Define the following:

(a) Exocrine gland

(b) Endocrine gland

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Solution

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Endocrine glands

These are ductless glands (no tube to carry to various parts).
Their secretions are directly released into the blood which carries them to various parts of the body.

Exocrine glands

The exocrine glands have ducts.
The secretions from these glands are carried through the ducts.
The ducts may open outside the body to release the secretions (e.g.sweat, milk) or may be released on to another surface within the body (e.g. Digestive juices)

Hormones

These are chemical messengers that regulate physiological processes in living organisms.
They act upon specific cells/tissues/organs which are called target cells/tissues/organs.
There are many types of hormones that act on different aspects of bodily functions and processes like growth and development.

Question 2

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

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Solution

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The endocrine system consists of glands widely separated from each other with no physical connections. Endocrine glands are groups of secretory cells surrounded by an extensive network of capillaries that facilitates diffusion of hormones from the secretory cells into the bloodstream.

The endocrine glands in the body are:

1) Pineal gland- located in the epithalamus, near the center of the brain.

2) Pituitary gland- located at the base of the brain, just below the hypothalamus.

3) Hypothalamus- located below the thalamus and above the pituitary gland and brain stem

4) Thyroid gland- located in the neck in front of the larynx and trachea

5) Parathyroid gland- located in the neck in the posterior surface of the thyroid gland

6) Adrenal gland- located on the upper pole of each kidney enclosed within the renal fascia

7) Pancreas- located deep inside the abdomen. The head of the pancreas is on the right side of the abdomen and is connected to the duodenum

8) Ovaries- located in the lower abdomen, laterally to the left and right of the uterus and inferior to the fallopian tubes

9) Testis- located between upper thighs suspended by the spermatic cord in a skin pouch called scrotum

10) Thymus gland- located in the upper anterior part of the chest directly behind the sternum and between the lungs

11) Heart- lies in the thoracic cavity in the mediastinum (space between the lungs)

12) Stomach- located in the superior aspect of the abdomen

13) Kidney- located against the back muscles in the upper abdominal area. The left kidney is located slightly more superior than the right kidney due to the larger size of the liver on the right side of the body.

Question 3

List the hormones secreted by the following:

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Solution

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The hormones secreted by the following are:

(a) Hypothalamus- thyrotropin releasing hormone (TRH), Corticotropin releasing hormone (CRH), gonadotropin-releasing hormone (GnRH), growth hormonereleasing hormone (GHRH), somatostatin, dopamine, follistatin, Melanocyte-inhibiting factor (melanostatin), etc.

(b) Pituitary- Hormones secreted by the anterior pituitary are: Growth Hormone (GH), Thyroid Stimulating Hormone (TSH), Adenocorticotrophic hormone (ACTH), Prolactin (PRL), Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH). Hormones secreted by the posterior pituitary are: Oxytocin, Antidiuretic hormone (ADH)

(d) Parathyroid- Parathyroid hormone (PTH)

(e) Adrenal- Adrenal cortex secretes: glucocorticids, mineralocorticoids and sex hormones (androgens). Adrenal medulla secretes: Adrenaline (epinephrine) and Nor-Adrenaline (nor-epinephrine)

(f) Pancreas- Insulina and glucagon

(g) Testis- Inhibin

(h) Ovary- Inhibin

(i) Thymus- Thymosin

(j) Atrium- Atrial natriuretic peptide (ANP)

(k) Kidney- Erythropoietin

(i) G-I Tract- Gastrin, Secretin, Cholecystokinin (CCK)

Question 4

Fill in the blanks:

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

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Solution

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Solution

a) Hypothalamic hormone- Pituitary gland

∙

Hypothalamic hormones include all the hormones like

1) thyrotropin-releasing

2) gonadotropin-releasing

3) growth hormone-releasing

4) corticotropin-releasing

5) somatostatin

6) dopamine hormones.

∙

Directly these hormones are released into the blood through the capillaries which travel to the pituitary gland and further processes occur.

b) Thyrotrophin(TSH)- Thyroid gland

∙

Thyrotropin(TSH) is produced by the master gland which works on the thyroid gland in stimulating the secretion of thyroxine hormone.

c) Corticotropin(ACTH)- Adrenal gland

∙

ACTH hormone is released by the master gland and stimulates the working of adrenal gland.

d) Gonadotrophins( LH, FSH)- Ovary and testis

∙

In males LH stimulates leydig cells which later release testosterone whereas FSH stimulates sertoli cells which stimulates spermatogenesis.

∙

In females ovaries are stimulated by both these hormones.

e) Melanotropin (MSH)- Melanocyte cells

∙

MSH directly stimulates the melanocyte cells present in the skin which release melanin which ultimately determines the skin color.

Question 5

Write short notes on the functions of the following hormones :

(a) Parathyroid hormone (PTH)

(b) Thyroid hormone

(d) Androgens

(e) Estrogens

(f) Insulin and glucogon

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Solution

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(a) Parathyroid hormone

The principal/chief cells of the parathyroid produce the parathyroid hormone, also called the parathormone. The function of this hormone is

To maintain calcium and phosphate balance in the blood and other tissues.
To increase calcium reabsorption from the intestine as well as from the nephrons of the kidney
To initiate bone resorption (e.g. reabsorption of calcium from bones), in case the blood calcium levels drop.

(b) Thyroid hormone

Both the thyroid hormones T

_{4}

(Thyroxine) and T

_{3}

(active form) are secreted by the thyroid gland.

The thyroid hormones control the metabolism of carbohydrates, protein and fats. They play an important role in regulating the Basal Metabolic Rate (BMR)
They are also important for maintenance of water and electrolyte balance.
Thyroid hormones also regulate the RBC production.
The thyrocalcitonin maintains the blood calcium levels and promotes the bone formation.

The thymus actively secretes the hormones called thymosins (only till pre-pubescence)

The stimulation, development and differntiation of T-lymphocytes.
The development of cell-mediated immunity (T-lymphocytes mediated immunity)
The production of antibodies (Humoral immunity).

(d) Androgens

Androgens are the hormones which are responsible for the development of secondary sexual characters. The Leydig cells of testis produce androgens such as testosterone.
Androgens are also produced by the adrenal cortex of the adrenal gland and the ovaries

(e) Estrogens

In Non-pregnant females, they are predominantly secreted by the ovaries. However, during pregnancy, the placenta secretes a lot of estrogens.
The three types of estrogens are; $β$ -estradiol, estrone and estriol.
The most active and the principal estrogen produced by the ovaries is the $β$ -estradiol.
They play an important role in the growth and development of ovarian follicles and breast
They are responsible for the development of secondary sexual characteristics (e.g. high pitch voice)
They inhibit osteoclastic activity and stimulate bone growth. Osteoporosis in menopausal women is because of reduced estrogen levels.

They also influence the texture of the skin and female sexual behaviour

(f) Insulin and Glucagon

Glucagon

It increases the blood glucose levels by initiating glycogenolysis (glycogen degradation) and stimulating gluconeogenesis (synthesis of glucose from non-carbohydrate molecules) in the liver cells.
Since it increases the blood glucose levels it is a hyperglycemic (hyper-more, glycemic-sugar levels) hormone
It also initiates lipolysis (degradation of lipid) in the adipose tissue.

Insulin

It is released when the glucose level in the blood raises.
It lowers blood sugar levels in different ways; increasing the uptake of glucose by all the cells in the body, initiating glycogenesis (glycogen synthesis) in the liver and muscle.
It initiates lipogenesis (synthesis of lipids/fat) and storage of fat in adipose tissue and inhibits gluconeogenesis
It is a hypoglycemic (hypo=less) hormone as it reduces the sugar levels in the blood

Question 6

Give example(s) of:

(a) Hyperglycemic hormone and hypoglycemic hormone

(b) Hypercalcemic hormone

(d) Progestational hormone

(e) Blood pressure lowering hormone

(f) Androgens and estrogens

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Solution

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Hyperglycemic hormone is glucagon, while hypoglycemic hormone is insulin.

Hypercalcemic hormone example is parathyroid hormone (PTH).

Gonadotrophic hormone examples are: LH (Luteinizing hormone) and FSH (Follicle stimulating hormone).

Progestational hormone example is progesterone.

Blood pressure lowering hormone example is Nor-adrenalin.

Androgen example is testosterone where as an example of estrogen is estradiol.

Question 7

Which hormonal deficiency is responsible for the following :

(a) Diabetes mellitus

(b) Goitre

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Solution

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(a) Diabetes mellitus is characterized by abnormally high glucose levels in the blood due to the deficiency of hormone, called insulin. Insulin helps the body use food for energy. When a person has diabetes, the pancreas either cannot produce enough insulin, or the body becomes resistant to insulin or both. Insulin stimulates the cells to uptake glucose. Lack of insulin or the inability of the cells to respond to insulin can lead to problems with the glucose uptake. Since the glucose is not taken up by the cells, the body will not get enough energy and several other problems associated with the increased blood glucose levels are also manifested.

(b) Goitre is characterized by an abnormal enlargement of the thyroid gland due to the deficiency of thyroxine hormone in the body. Symptoms of a goiter include enlargement of the throat, ranging from a small lump to a huge mass, swallowing problems and breathing problems.

(c) Cretinism is characterized by stunted growth in the baby due to the deficiency of thyroid hormone in the body. It usually results from a congenital defect (e.g., an absence of the thyroid, the presence of only a rudimentary gland, the inability of the gland to produce thyroxine). However, it can develop later if there is a lack of iodine in the diet, or if the thyroid is diseased or surgically removed.

Question 8

Explain the role of FSH and LH.

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Solution

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Follicle Stimulating Hormone (FSH) and Leutinizing Hormone (LH) are released by the pituitary gland.
In females, FSH is responsible for stimulating the growth of ovarian follicles for the formation of oocytes and ovum. In males, FSH is responsible for activating Sertoli Cells so that they can stimulate the spermatogenesis.
In females. the LH is responsible for stimulating the ovulation, that is, the release of the ovum. In males, LH is responsible for activating the Leydig's cell to secrete the testosterone.

Question 9

Match the column.

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

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Solution

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T_{4}

is a hormone produced by the thyroid gland. PTH is parathyroid hormone or parathormone produced by the parathyroid gland. GnRH is the gonadotropin-releasing hormone secreted by the hypothalamus and LH is luteinizing hormone secreted by the pituitary gland.

Question 10

List the hormones secreted by pancreas.

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Solution

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The four main hormones produced by the endocrine pancreas and their functions are
Glucagon

It is a polypeptide hormone.
It is secreted by the pancreas when the glucose level in the blood drops.
It increases the blood glucose levels by initiating glycogenolysis (glycogen degradation) and stimulating gluconeogenesis (synthesis of glucose from non-carbohydrate molecules) in the liver cells.
Since it increases the blood glucose levels it is a hyperglycemic (hyper-more, glycemic-sugar levels) hormone
It also initiates lipolysis (degradation of lipid) in the adipose tissue.

Insulin

It is also a polypeptide hormone
It has antagonistic (opposite) effects of the hormone glucagon.
It is released when the glucose level in the blood raises.
It lowers blood sugar levels in different ways; increasing the uptake of glucose by all the cells in the body, initiating glycogenesis (glycogen synthesis) in the liver and muscle.
It initiates lipogenesis (synthesis of lipids/fat) and storage of fat in adipose tissue and inhibits gluconeogenesis
It is a hypoglycemic (hypo=less) hormone as it reduces the sugar levels in the blood

Somatostatin

Also known as growth hormone-inhibiting hormone (GHIH)
It acts locally on the Islets of Langerhans and inhibit the secretion of both insulin and glucagon
It also reduces gastric secretions and inhibits the release of gastrointestinal hormones

Pancreatic Polypeptide

It is a polypeptide secreted by the cells of the pancreas.
Protein is strong stimulus for its production
It affects gastric and biliary secretion and motility of the GI tract

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NCERT Solutions for Class 11 Biology Chapter 22 : Chemical Control and Integration

NCERT Solutions for Class 11 Biology Chapter 22 Chemical Control and Integration – Brief Overview

22.1 – Endocrine Glands and Hormones

In this, you will study about endocrine glands which are ductless glands and release their secretion directly into the blood which is then transported to specific target organs to initiate a particular metabolic change.

22.2 – Human Endocrine System

It deals with endocrine glands and hormone-producing tissues/cells are located in different parts of the body to control and coordinate the function of respective organs.

22.2.1 – The Hypothalamus

In this, you will study about hypothalamus which regulates the synthesis and secretion of pituitary hormones.

22.2.2 – The Pituitary Gland

In this, you will study about pituitary gland which secrets growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, prolactin.

22.2.3 – The Pineal Gland

In this, you will study about pineal gland which releases melatonin hormone that helps to regulate the diurnal rhythm of the body like a sleep-wake cycle and body temperature.

2.2.4 – Thyroid Gland

In this, you will study about thyroid gland which secretes Thyroid hormones regulate the basal metabolic rate.

22.2.5 – Parathyroid Gland

In this, you will study about parathyroid gland which secretes peptide hormone, regulates the calcium ion concentration in the blood.

22.2.6 – Thymus

In this, you will study about thymus which releases peptide hormone thymosins that help in differentiation of T-Lymphocytes for cell-mediated immunity.

22.2.7 – Adrenal Gland

In this, you will study about adrenal gland which secretes adrenaline and noradrenalin hormone, glucocorticoids and mineral corticoids.

22.2.8 – Pancreas

In this, you will study about pancreas which secretes hormone glucagon, secrete insulin

22.2.9 – Testis

In this, you will study about testis which secretes testosterone which regulates maturation of primary sex organs and spermatogenesis

22.2.10 – Ovary

In this, you will study about ovary which secretes estrogen and progesterone.

22.3 – Hormones of Heart, Kidney and Gastrointestinal Tract

In this, you will study about secretion of atrial wall of heart secretes peptide hormone, erythropoietin hormone, hydrochloric acid and pepsinogen, pancreatic enzymes and bile juice, gastric inhibitory peptide.

22.4 – Mechanism of Hormone Action

In this, you will study about mechanism of hormone which hormone produce their effects on target tissues by binding to specific protein located in the target tissue.

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Frequently Asked Questions on NCERT Class 11 Biology Chapter 22 : Chemical Control and Integration

Q1. What are the benefits of solutions for NCERT Class 11 Biology Chapter 22 Chemical Control and Integration?

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Q2. Are the NCERT Solutions for Class 11 Biology Chapter 22 Chemical Control and Integration the best study materials for CBSE students?

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