19. Chemical Coordination and Integration

Class 11 Biology Chapter 19 Chemical Coordination and Integration

Chapter 19 Chemical Coordination and Integration

Class 11 Biology Chapter 19 Chemical Coordination and Integration Exercise Questions and Answers :

1. Define the following :

(a) Exocrine gland

(b) Endocrine gland

Answer : (a) Exocrine Gland : An exocrine gland is a type of gland that secretes its products, such as enzymes, mucus, or other substances, into ducts that lead to the body's external environment or specific internal cavities (like the digestive tract or the skin's surface). These glands play a role in tasks like digestion, temperature regulation, and protection, and their secretions are usually delivered directly to the site where they are needed. Examples of exocrine glands include salivary glands, sweat glands, and oil-secreting glands in the skin.

(b) Endocrine Gland : An endocrine gland is a type of gland that secretes hormones directly into the bloodstream rather than through ducts. These hormones are chemical messengers that travel throughout the body to regulate various physiological processes, including growth and development, metabolism, mood, and reproductive functions. Endocrine glands include the pituitary gland, thyroid gland, adrenal glands, and pancreas, among others.

(c) Hormone : A hormone is a regulatory chemical substance produced by specialized cells or glands in the endocrine system. Hormones serve as messengers that travel through the bloodstream to target cells or organs, where they exert specific effects on various physiological processes. Hormones are essential for maintaining homeostasis, coordinating growth and development, responding to stress, and regulating functions such as metabolism, immune response, and reproduction. Examples of hormones include insulin, estrogen, testosterone, thyroid hormones, and adrenaline, among many others. Hormones play a critical role in coordinating the activities of different organs and systems in the body.

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

Answer : The diagram of the location of the various endocrine glands in our body :

3. 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 : The hormones secreted by each of the specified glands and organs:

Gland/Organ	Hormones Secreted
(a) Hypothalamus	Gonadotropin-releasing hormone (GnRH)
	Corticotropin-releasing hormone (CRH)
	Thyrotropin-releasing hormone (TRH)
	Growth hormone-releasing hormone (GHRH)
	Somatostatin (Growth hormone-inhibiting hormone)
	Prolactin-releasing hormone (PRH)
	Prolactin-inhibiting hormone (PIH or dopamine)
(b) Pituitary	Anterior Pituitary:
	Growth Hormone (GH)
	Prolactin (PRL)
	Thyroid-Stimulating Hormone (TSH)
	Adrenocorticotropic Hormone (ACTH)
	Follicle-Stimulating Hormone (FSH)
	Luteinizing Hormone (LH)
	Posterior Pituitary:
	Oxytocin
	Antidiuretic Hormone (ADH, Vasopressin)
(c) Thyroid	Thyroxine ()
	Triiodothyronine ()
	Calcitonin
(d) Parathyroid	Parathyroid Hormone (PTH)
(e) Adrenal	Adrenal Cortex:
	Cortisol
	Aldosterone
	Androgens
	Adrenal Medulla:
	Epinephrine (Adrenaline)
	Norepinephrine (Noradrenaline)
(f) Pancreas	Insulin
	Glucagon
	Somatostatin
(g) Testis	Testosterone
(h) Ovary	Estrogens (such as estradiol)
(h) Ovary	Progesterone
(i) Thymus	Thymosin
(j) Atrium	Atrial Natriuretic Peptide (ANP)
(k) Kidney	Erythropoietin (EPO)
(k) Kidney	Renin
(l) G - I Tract	Various hormones, including gastrin, cholecystokinin (CCK), secretin, and others, involved in regulating digestion and nutrient absorption.

4. Fill in the blanks:

Hormones Target gland

(a) Hypothalamic hormones __________________

(b) Thyrotrophin (TSH) __________________

(d) Gonadotrophins (LH, FSH) __________________

(e) Melanotrophin (MSH) __________________

Answer : (a) Hypothalamic hormones ----- Pituitary gland

(b) Thyrotrophin (TSH) ------ Thyroid gland

(d) Gonadotrophins (LH, FSH) ------ Testis and Ovaries (Gonads)

(e) Melanotrophin (MSH) ------ Skin and other tissues

5. Write short notes on the functions of the following hormones:

(a) Parathyroid hormone (PTH) (b) Thyroid hormones

(e) Estrogens (f) Insulin and Glucagon

Answer : (a) Parathyroid Hormone (PTH) :

Function : PTH is secreted by the parathyroid glands and plays a crucial role in regulating calcium and phosphate levels in the blood.

Its main functions are:

(i) Increasing calcium reabsorption in the kidneys, reducing calcium excretion in urine.

(ii) Stimulating the release of calcium from bones, which increases blood calcium levels.

(iii) Enhancing the absorption of dietary calcium in the intestines.

(iv) Reducing phosphate reabsorption in the kidneys, leading to increased phosphate excretion.

(b) Thyroid Hormones ( and ) :

Function: Thyroid hormones, including thyroxine () and triiodothyronine (), are produced by the thyroid gland and are essential for regulating the body's metabolism.

Their functions are :

(i) Increasing the basal metabolic rate (BMR), which affects overall energy expenditure.

(ii) Promoting normal growth and development, especially in children.

(iii) Regulating body temperature, heart rate, and digestive processes.

(iv) Influencing the function of various organs and tissues in the body.

Function: Thymosins are a group of hormones produced by the thymus gland. Their primary function is to support the development and maturation of T-lymphocytes (T cells), which are critical components of the immune system. Thymosins help in the production and activation of T cells, which play a vital role in the body's immune response against infections and diseases.

(d) Androgens:

Function: Androgens, such as testosterone, are male sex hormones produced primarily by the testes (and in smaller amounts by the adrenal glands).

Their functions are :

(i) Promoting the development of male secondary sexual characteristics, such as facial hair and a deep voice.

(ii) Regulating sperm production (spermatogenesis).

(iii) Supporting muscle and bone growth.

(iv) Influencing sex drive and overall sexual function.

(e) Estrogens:

Function: Estrogens are a group of female sex hormones produced primarily by the ovaries (and in smaller amounts by the adrenal glands and fat cells).

Their functions are :

(i) Promoting the development of female secondary sexual characteristics, such as breast development and a wider pelvis.

(ii) Regulating the menstrual cycle and supporting reproductive health.

(iii) Maintaining bone density and cardiovascular health.

(iv) Influencing mood, skin health, and overall well-being.

(f) Insulin and Glucagon :

Function: Insulin and glucagon are hormones produced by the pancreas, and they work together to regulate blood glucose (sugar) levels.

(i) Insulin: Promotes the uptake of glucose into cells, reducing blood sugar levels. It facilitates the storage of glucose as glycogen in the liver and muscles and is crucial for regulating glucose metabolism.

(ii) Glucagon: Raises blood sugar levels by promoting the breakdown of glycogen in the liver and stimulating the release of glucose into the bloodstream. It is essential in preventing hypoglycemia (low blood sugar).

These hormones play critical roles in maintaining various physiological processes in the body and ensuring overall health and homeostasis.

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

Answer : (a) Hyperglycemic hormone and hypoglycemic hormone :

Hyperglycemic hormone : Glucagon is an example of a hyperglycemic hormone. It is released by the pancreas and elevates blood glucose levels by promoting the release of stored glucose from the liver.

Hypoglycemic hormone : Insulin is an example of a hypoglycemic hormone. It is also produced by the pancreas and lowers blood glucose levels by facilitating the uptake of glucose by cells and the storage of excess glucose in the form of glycogen.

(b) Hypercalcemic hormone :

Parathyroid Hormone (PTH) : PTH is an example of a hypercalcemic hormone. It is produced by the parathyroid glands and raises blood calcium levels by stimulating the release of calcium from bones, increasing calcium reabsorption in the kidneys, and promoting the absorption of dietary calcium in the intestines.

Gonadotrophic hormones are released by the anterior pituitary gland and include:

Follicle-Stimulating Hormone (FSH) : FSH plays a key role in the development of ovarian follicles in females and the production of sperm in males.

Luteinizing Hormone (LH) : LH is involved in the maturation of the ovarian follicle, ovulation, and the production of sex hormones, such as estrogen and progesterone in females. In males, LH stimulates the testes to produce testosterone.

(d) Progestational hormone :

Progesterone : Progesterone is a progestational hormone produced by the corpus luteum in the ovaries and, during pregnancy, by the placenta. It prepares the uterine lining for implantation of a fertilized egg and helps maintain the pregnancy. Progesterone is also involved in regulating the menstrual cycle.

(e) Blood pressure-lowering hormone :

Atrial Natriuretic Peptide (ANP) : ANP is a hormone produced and released by the atria of the heart in response to increased blood volume and pressure. It acts to reduce blood pressure by promoting vasodilation (widening of blood vessels) and increasing the excretion of sodium and water by the kidneys.

(f) Androgens and estrogens :

Androgens : Testosterone is a well-known androgen, primarily produced by the testes in males (and in smaller amounts by the ovaries in females and the adrenal glands in both sexes). Androgens are male sex hormones responsible for the development of male secondary sexual characteristics and supporting functions like sperm production.

Estrogens : Estradiol is a prominent estrogen, mainly produced by the ovaries in females (and in smaller quantities by the testes in males and the adrenal glands in both sexes). Estrogens are female sex hormones that play a crucial role in the development of female secondary sexual characteristics and regulate the menstrual cycle and reproductive processes.

7. Which hormonal deficiency is responsible for the following:

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

Answer : (a) Diabetes mellitus:

The deficiency responsible for diabetes mellitus is typically a lack of the hormone insulin or a reduced sensitivity of cells to insulin.

In type 1 diabetes, there is a deficiency of insulin because the insulin-producing beta cells in the pancreas are destroyed.

In type 2 diabetes, there may be a relative deficiency of insulin due to decreased sensitivity of cells to its effects (insulin resistance), even though insulin is still being produced.

(b) Goitre:

Goitre is often associated with a deficiency in the hormone thyroid hormone, specifically thyroxine () and triiodothyronine ().

In most cases, goitre is caused by an iodine deficiency, which impairs the thyroid gland's ability to produce sufficient thyroid hormones. In response to low thyroid hormone levels, the pituitary gland may release more thyroid-stimulating hormone (TSH), causing the thyroid gland to enlarge in an attempt to produce more thyroid hormones.

Cretinism, a congenital and severe form of hypothyroidism, is characterized by stunted physical and mental development. It is caused by a deficiency of thyroid hormones, especially during fetal development and infancy.

In most cases, this condition is due to inadequate thyroid gland function or a congenital absence of the thyroid gland, leading to insufficient production of thyroid hormones. If left untreated, cretinism can result in profound developmental and intellectual disabilities.

8. Briefly mention the mechanism of action of FSH.

Answer : Follicle-Stimulating Hormone (FSH) exerts its effects by binding to specific membrane-bound receptors on target cells in the gonads, which can be either the ovaries in females or the testes in males. This binding event initiates a series of biochemical changes within the target tissue. FSH, being a peptide hormone, does not enter the target cell but instead triggers the generation of second messengers, such as cyclic AMP (cAMP). These second messengers then regulate cellular metabolism, leading to processes like the growth and development of ovarian follicles in females or spermatogenesis in males. The cumulative biochemical actions of FSH result in the physiological and developmental effects associated with reproductive function.

9. Match the following:

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

Answer : The matching for the items in Column I with those in Column II :

(a) ----------- (ii) Thyroid

(b) PTH ----------- (iv) Parathyroid

(d) LH ------------ (iii) Pituitary