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

In the immediate above chapter, we have seen how the neural system maintains point-to-point rapid coordination between organs. This coordination provided by the neural system is fast, but not long. Therefore, a special form of coordination and integration is required, since the nerve fibres do not stimulate all cells of the body, and there is a necessity to regulate the functions of the cells continuously.

Hormones perform this special coordination function. The body's physiological functions are jointly regulated and coordinated by the neural system and the endocrine system. To know more about them read below.

• What is Endocrine Glands and Hormones
• The Endocrine System of Humans
• Hormones present in Kidney, Gastrointestinal Tract, and Heart
• Mechanics applied in Hormone Action

The last chapter for class 11 Biology' Chemical Coordination and Integration' explains the concept of endocrine glands present in the human body. The chapter has been explained minutely through diagrams so that students exactly trace the location of the endocrine glands inside the human body.

In this chapter, Hormones are defined as non-nutrient chemicals whose nature is like intercellular messengers and which generate in huge numbers to play a pivotal role in the endocrine system. Also discussed is an overview of FSH's process and the hormonal deficiencies occurring in different parts of the human body. Some other topics introduced in this chapter are the pituitary gland, thyroid gland, pineal gland, hypothalamus, thymus, parathyroid gland, pancreas, adrenal gland, ovary, testis, and the mechanism of hormonal action.

Q1. Define the following:
(a)Exocrine gland
Answer:
Exocrine gland-
The glands which discharge their secretions into ducts are known as exocrine glands. Examples of exocrine glands include the sebaceous gland in the skin, the salivary gland in the buccal cavity, etc.
 

Q2. Define the following:
(b)Endocrine gland
Answer:
Endocrine glands-
The glands which do not discharge their secretions into ducts are known as endocrine glands. These glands discharge their secretions directly into the blood. Examples of endocrine glands include the Pituitary gland, thyroid gland, adrenal gland, etc.

Q3. Define the following:
(c)Hormone
Answer:
Hormones-
The hormones are chemical messengers that regulate physiological processes in living organisms. They act upon specific cells/tissues/organs.

Q4. Diagrammatically indicate the location of the various endocrine glands in our body.
Answer:
The location of the various endocrine glands in our body is depicted below.

Q5. List the hormones secreted by the following:
(a)Hypothalamus
Answer:
The hormones secreted by the hypothalamus include divided into two groups-
1. Releasing hormones- These include gonadotropin-releasing hormone, thyrotropin-releasing hormone, somatotropin-releasing hormone, adrenocorticotropin-releasing hormone.

2. Inhibiting hormones: These include somatostatin, growth-inhibiting hormone, melanocyte-inhibiting hormone

Q6. List the hormones secreted by the following:
(b)Pituitary
Answer:
The pituitary gland has two components i.e., adenohypophysis and neurohypophysis.
-Hormones secreted by the adenohypophysis are growth hormone (GH), prolactin, thyroid-stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), melanocyte-stimulating hormone (MSH)
-Hormones secreted by the neurohypophysis are oxytocin and vasopressin

Q7. List the hormones secreted by the following:
(c) Thyroid
Answer:
Thyroid gland- The thyroid gland secretes three hormones namely, thyroxin, tri-iodothyronine, and calcitonin.

Q8. List the hormones secreted by the following:
(d)Parathyroid
Answer:
Parathyroid- It secretes parathyroid hormone
 

Q9. List the hormones secreted by the following:
(e)Adrenal
Answer:
Adrenal gland - The adrenal gland is divided into two parts, the outer adrenal cortex, and the inner adrenal medulla.
-Hormones of the adrenal cortex include aldosterone and cortisol.
- Hormones of the adrenal medulla are adrenaline and nor-adrenalin. 
 

Q9.List the hormones secreted by the following:
(f)Pancreas
Answer:
Pancreas: Hormones secreted by the pancreas are insulin, glucagon and somatostatin.

Q10. List the hormones secreted by the following:
(g)Testis
Answer:
Testis: The hormone secreted by the testis is testosterone.

Q11. List the hormones secreted by the following:
(h)Ovary
Answer:
Ovary: The hormone secreted by the ovary includes estrogen and progesterone.

Q12. List the hormones secreted by the following:
(i)Thymus
Answer:
Thymus: Hormones secreted by the thymus are thymosin.

Q13. List the hormones secreted by the following:
(j)Atrium
Answer:
Atrium: The walls of the atrium secrete atrial natriuretic factors.

Q14. List the hormones secreted by the following:
(k)Kidney
Answer:
Kidney: The hormone secreted by the kidney is erythropoietin.

Q15. List the hormones secreted by the following:
(l)G-I Tract
Answer:
G-l tract- The hormones secreted by the G-l tract are Gastrin, secretin, cholecystokinin (CCK), and gastric inhibitory peptide (GIP).

Q16. Fill in the blanks:

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

Answer:

Hormones Target gland
a. Hypothalamic hormones- Pituitary gland.
b. Thyrotrophin (TSH) -Thyroid gland 
c. Corticotrophin (ACTH)- Adrenal gland
d. Gonadotrophins (LH, FSH)- Testis and ovaries 
e. Melanotropin (MSH)- Pigment cells of the dermis of the skin


Q17. Write short notes on the functions of the following hormones:
a. Parathyroid hormone (PTH)
Answer:
The function of 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 demineralizes bones increasing blood calcium levels.
-It also stimulates calcium absorption by renal tubules and from the digested food.


Q18. Write short notes on the functions of the following hormones:
b. Thyroid hormone
Answer:
The function of Thyroid hormones are given below:

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.

Q19. Write short notes on the functions of the following hormones:
c. Thymosin
Answer:
The function of Thymosins is given below:

-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.

Q20. Write short notes on the functions of the following hormones:
d. Androgens
Answer:
The function of Androgens are given below:

Testosterone:
-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 beards and moustaches.
-It produces anabolic effects on protein and carbohydrate metabolism.

Q21. Write short notes on the functions of the following hormones:
e. Estrogen
Answer:
The primary function of estrogens in the development of female secondary sexual characteristics. These include breasts, endometrium, regulation of the menstrual cycle, etc. In males, estrogen helps in the maturation of the sperm and the moustaches of a healthy libido.

Q22. Write short notes on the functions of the following hormones:
f. Insulin and Glucagon
Answer:
The function of Insulin and Glucagon are given below:

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

Glucagon:
-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.

Q23. Give example(s) of:
a. Hyperglycemic hormone and (b)hypoglycemic hormone
Answer:
a. Hyperglycemic hormone- glucagon.
b. Hypoglycemic hormone -insulin


Q24. Give example(s) of:
c. Hypercalcemic hormone
Answer: Parathormone 

Q25. Give example(s) of:
d. Gonadotrophic hormone
Answer:
-Luteinising hormone (LH)
-Follicle-stimulating hormone (FSH)

Q26. Give example(s) of:
e. Progestational hormone
Answer: Progesterone

Q27. Give example(s) of:
f. Blood pressure-lowering hormone
Answer:Atrial natriuretic factor

Q28. Give example(s) of:
g. Androgens and estrogens
Answer:
Androgens: Testosterone 
Estrogens : estradiol

Q29. Which hormonal deficiency is responsible for the following:
(a)Diabetes Mellitus
Answer:
Insufficient secretion of insulin is responsible for Diabetes Mellitus.

Q30. Which hormonal deficiency is responsible for the following:
(b)GoitreAnswer:
Insufficient secretion of thyroxine is responsible for Goitre.

Q31. Which hormonal deficiency is responsible for the following:
(c)Cretinismthe a the The locationHypothalamusthyrotropin-releasing the the factorsThefunctione function funfunction in thethe
Answer:
Insufficient secretion of thyroxine is responsible.

Q32. Briefly mention the mechanism of action of FSH.

Answer:
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 athe ction of FSH:
-A molecule of FSH binds on the receptor protein present on the cell surface and forms the hormone-receptor complex.
-The formation of the hormone-receptor complex activates the enzyme adenylate cyclase.
-Adenyl cyclase converts ATP into cell cyclic adenosine monophosphate (cAMP) as a second messenger.
-cAMP activates the follicular cells of membrane granulosa to secrete estrogens.

Q9. Match the following:

Answer:

Download PDF For FREE