19.6 Exercise Problems

Q1. Define the following:
(a) Exocrine gland
(b) Endocrine gland
(c) Hormone

Answer: (a) Exocrine Glands
Glands that discharge secretions into ducts are known as exocrine glands. Sebaceous gland in the skin, salivary gland in the buccal cavity, etc. ectopic collections of sebaceous glands in oral cavity are called Fordyce granules are examples of exocrine glands.
(b) Endocrine Glands
Glands that do not discharge their secretions into ducts are known as endocrine glands. Instead, these glands discharge their secretions directly into the blood. Pituitary gland, thyroid gland, adrenal gland, etc. are examples of endocrine glands.
(c) Hormones
Hormones are chemical messengers that regulate physiological processes in living organisms. They act upon specific cells/tissues/organs which are called target cells/tissues/organs.

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

Answer: The location of various endocrine glands in the human body can be illustrated as follows:

Q3. List the hormones secreted by the following:
(a) Hypothalamus
(b) Pituitary
(c) Thyroid
(d) Parathyrold
(e) Adrenal
(f) Pancreas
(g) Testis
(h) Ovary
(i) Thymus
(j) Atrium
(k) Kidney
(l) G-I Tract

Answer: (a) Hypothalamus
Hormones secreted by hypothalamus include Releasing Hormones. These hormones stimulate the secretion of the pituitary hormone. Examples of these hormones are:
i. Gonadotrophin-releasing hormone
ii. Thyrotrophin-releasing hormone
iii. Somatotropin-releasing hormone
iv. Adrenocorticotrophin-releasing hormone
Inhibiting Hormones inhibit the secretions of the pituitary hormone. Examples of these hormones are:
i. Somatostatin
ii. Growth-inhibiting hormone
iii. Melanocyte-inhibiting hormone
(b) Pituitary: The pituitary gland has two components, i.e., adenohypophysis and neurohypophysis. Hormones secreted by the adenohypophysis are:
i. Growth hormone (GH)
ii. Prolactin
iii. Thyroid-stimulating hormone (TSH)
iv. Adrenocorticotrophic hormone (ACTH)
v. Luteinizing hormone (LH)
vi. Follicle-stimulating hormone (FSH)
vii. Melanocyte-stimulating hormone (MSH)
Hormones secreted by the neurohyphysis are:
I. Oxytocin
II. Vasopressin
(c) Thyroid: The thyroid gland secretes 3 hormones namely, thyroxin, triiodothyronin and calcitonin ( \(\mathrm{t} 3 ~\mathrm{t} 4\) )
(d) Parathyroid: Secretes a hormone known as parathyroid hormone.
(e) Adrenal: The adrenal gland is divided into 2 parts, the outer adrenal cortex and the inner adrenal medulla. Hormones of adrenal cortex include the following:
i. Mineralocorticoids: Secreted is known as adlosterone.
ii. Glucocorticoids: Secreted is cortisol.
Hormones of adrenal medulla are adrenal and nor-adrenalin.
(f) Pancreas: insulin and glucagon.
(g) Testis: testosterone.
(h) Ovary: estrogen and progesterone.
(i) Thymus: Hormones secreted by the thymus are thymosins.
(j) Atrium: The walls of the atrium secrete atrial natriuretic factor.
(k) Kidney: erythropoietin.
(I) G-I tract: Gastrin, secretin, cholecystokinin (CCK), and gastric inhibitory peptide (GIP).

Q4. Fill in the blanks: 

\(
\begin{array}{ll}
\text { Hormone } & \text { Target gland } \\
\text { (a) Hypthalamic hormones } & – \\
\text { (b) Thyrotrophin(TSH) } & – \\
\text { (c) Corticotrophin(ACTH) } & – \\
\text { (d) Gonadotrophins(LH,FSH) } & – \\
\text { (e) Melanotrophin(MSH) } & –
\end{array}
\)

Answer: 

(a) Pituitary
(b) Thyroid
(c) Adrenal
(d) Ovary, Testis
(e) Melanocyte

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 (PTH)
Its main function is to increase the level of calcium in blood. It promotes the reabsorption of calcium from nephrons and also, promotes the absorption of calcium from digested food. Hence, it plays an important role in maintaining calcium balance in the body.
(b) Thyroid hormones
Thyroxine, triiodothyronin, and thyrocalcitonin are secreted by the thyroid gland. Thyroxine maintains the basal metabolic rate of the body and regulates the carbohydrate, fat, and protein metabolism. Water and electrolyte balance is also maintained by thyroid hormones. Thyrocalcitonin or calcitonin lowers calcium level in blood plasma. It plays a significant role in calcium levels along with parathyroid hormone.
(c) Thysmosins
Thysmosin is secreted by the thymus gland. Major role in immunity and also. Thymosins also help in the development of sex glands.
(d) Androgens
Testosterone is a male sex hormone that regulates the development of secondary sex characteristics such as facial hair, hoarse voice, development of reproductive organ, etc. Androgens also regulate the development, maturation, and functions of various male accessory organs such as epididymis and prostate glands. It stimulates spermatogenesis and the formation of mature sperms. It also influences male sexual behaviour.
(e) Estrogens
Estrogen is the female sex hormone that controls the development of secondary sex characteristics such as enlargement of breasts and development of female reproductive organs. It plays a role in the development, growth and maturation of female secondary characteristics. It also helps in the development of growing ovarian follicles.
(f) Insulin and Glucagon
They regulate the blood glucos level in the body. \(\alpha\) – cells secrete glucagon that maintain a normal blood glucose level in the body, whereas \(\beta \text {-cells }\) secrete insulin that regulates the storage of glycogen in the liver.
i. Function of insulin (conversion of glucose to glycogen). The rapid conversion of glucose from the blood to glycogen in hepatocytes and adipocytes results into a decreased glucose level. Insulin also prevents the formation of glucose from non-carbohydrate substances such as proteins and fats. So, it acts as a regulator of carbohydrate metabolism.
ii. Function of glucagon – The main function of the glucagon is to increase the level of glucose when there is a deficiency of glucose in the body. This process is known as glycogenolysis.

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 and hypoglycemic hormone
Hyperglycemic hormone is glucagon, while hypoglycemic hormone is insulin.
(b) Hypercalcemic Hormone
Parathyroid hormone (PTH) is hypercalcemic hormone.
(c) Gonadotrophi Chormones
Luteinizing hormone and follicle stimulating hormones are examples of gonadotrophic hormone.
(d) Progestational Hormone
Progesterone is a progestational hormone.
(e) Blood Pressure Lowering Hormone
Nor-adrenalin is a blood pressure-lowering hormone
(f) Androgens and Estrogens
Testosterone is an example of androgen, while an example of estrogen is estradiol.

Q7. Which hormonal deficiency is responsible for the following:
(a) Diabetes mellitus
(b) Goitre
(c) Cretinism

Answer: (a) Diabetes mellitus
Diabetes mellitus is characterized by abnormally high glucose levels in the blood due to the deficiency hormone, called insulin.
(b) Goitre
Goitre is characterized by an abnormal enlargement of the thyroid gland due to the deficiency of thyroxin hormone in the body.
(c) Cretinism
Cretinism is characterized by stunted growth in the baby due to the deficiency of thyroid hormone in the body.

Q8. Briefly mention the mechanism of action of FSH.

Answer: Follicle-stimulating hormone (FSH) is secreted by the pats distalis region of the anterior pituitary. In the ovary, FSH stimulates the growth and maturation of ovarian follicle. As the follicle grows and matures, it releases an inhibitory hormone known as inhibin that ends the process of FSH production.
Action of FSH: Follicle stimulating hormone produces its effect by binding to its specific receptors present on the ovarian cell membrane.
Binding of FSH hormone to its receptor leads to the formation of hormone receptors complex. The ovarian follicles mature and release a mature ovum in the fallopian tube for fertilization.

Q9. Match the following:

\(
\begin{array}{|l|l||}
\hline \text { Column I } & \text { Column II } \\
\hline \hline \text { (a) } T_4 & \text { (i) Hypothalamus } \\
\hline \text { (b) PTH } & \text { (ii) Thyroid } \\
\hline \text { (c) GnRH } & \text { (iii) Pituitary } \\
\hline \text { (d) } L H & \text { (iv) Parathyroid } \\
\hline
\end{array}
\)

Answer: 

\(
\begin{array}{|l|l||}
\hline \text { Column I } & \text { Column II } \\
\hline \hline \text { (a) } T_4 & \text { (ii) Thyroid } \\
\hline \text { (b) PTH } & \text { (iv) Parathyroid } \\
\hline \text { (c) GnRH } & \text {(i) Hypothalamus } \\
\hline \text { (d) } L H & \text { (iii) Pituitary } \\
\hline
\end{array}
\)

Exemplar Section

VERY SHORT ANSWER TYPE QUESTIONS

Q1. There are many endocrine glands in human body. Name the glands which is absent in male and the one absent in female.

Answer: In Males—Ovary and in Females—Testis.

Q2. Which of the two adrenocortical layers, zona glomerulosa and zona reticularis lies outside enveloping the other?

Answer: Outer layer—Zona glomerulosa
Inner layer—Zona reticularis

Q3. What is erythropoiesis? Which hormone stimulate it?

Answer: Formation of RBC is known as erythropoiesis and the hormone erythropoietin stimulates the process.

Q4. Name the only hormone secreted by pars intermedia of the pituitary gland.

Answer: MSH or Intermedin

Q5. Name the endocrine gland that produces calcitonin and mention the role played by this hormone. 

Answer: Thyroid gland also secretes a protein hormone called thyrocalcitonin (TCT) which regulates the blood calcium levels. TCT is secreted by ‘C’ cells of thyroid glands. TCT is a hypocalcaemic hormone which lower the blood calcium level by increasing calcium deposition in the bones, so checks osteoporosis.

Q6. Name the hormone that helps in cell – mediated immunity

Answer: Thymosin

Q7. What is the role of second messenger in the mechanism of protein hormone action?

Answer: The Second messenger helps in regulating cell metabolism. The hormones which react with the membrane-bound receptors generally do not enter the cell. Instead of that, they create second messengers and in doing so, affect the functioning of the target cells.

Q8. State whether true or false:
a. Gastrointestinal tract, kidney and heart also produce hormones.
b. Pars distalis produces six trophic hormones.
c. B-lymphocytes provide cell-mediated immunity.
d. Insulin resistance results in a disease called diabetes mellitus.

Answer: a. True
b. True
c. False because T. lymphocytes provide cell-mediated immunity and B-lymphocytes provide humoral immunity which is a type of adaptive immune system.
d. True

Q9. A patient complains of constant thirst, excessive passing of urine and low blood pressure. When the doctor checked the patients’ blood glucose and blood insulin level, the level were normal or slightly low. The doctor diagnosed the condition as diabetes insupidus. But he decided to measure one more hormone in patients blood. Which hormone does the doctor intend to measure?

Answer: Doctor intends to measure vasopressin hormone because this hormone increases the reabsorption of water by the kidney and deficiency of this hormone decreases reabsorption of water.

Q10. Correct the following statements by replacing the term underlined.
a. Insulin is a steroid hormone.
b. TSH is secreted from the corpus luteum
c. Tetraiodothyronine is an emergency hormone.
d. The pineal gland is located on the anterior part of the kidney.

Answer: (a) Insulin is a protein hormone
(b) TSH is secreted from the anterior pituitary.
(c) Adrenaline is an emergency hormone.
(d) The adrenal gland is located on the anterior part of the kidney.

Q11. Rearrange the following hormones in Column I so as to match with their chemical nature in Column II.
\(
\begin{array}{|l|l|}
\hline \text { Column I } & \text { Column II } \\
\text { a. Oxytocin } & \text { i. Amino acid derivative ( ) } \\
\text { b. Epinephrine } & \text { ii. Steroid ( ) } \\
\text { c. Progesterone } & \text { iii. Protein ( ) } \\
\text { d. Growth hormone } & \text { iv. Peptide ( ) } \\
\hline
\end{array}
\)

Answer:

\(
\begin{aligned}
& \mathrm{a}-\mathrm{iv}, \\
& \mathrm{b}-\mathrm{i}, \\
& \mathrm{c}-\mathrm{ii}, \\
& \mathrm{d}-\mathrm{iii} .
\end{aligned}
\)

SHORT ANSWER TYPE QUESTIONS

Q1. What is the role-played by luteinizing hormones in males and females respectively?

Answer: LH stimulates the synthesis and secretion of androgens called male hormones. In females, LH is essential for ovulation. In females, LH induces ovulation of fully mature follicles (graafian follicles) and maintains the corpus luteum formed from the remnants of the graafian follicles after ovulation.

Q2. What is the role of second messenger in hormone action?

Answer: Hormones which do not enter the target cell, interact with specific receptors located on the surface of the target cell membranes and generates second messengers (e.g., cAMP) on the inner side of plasma membrane. The second messenger, in turn, carries out all the hormonal functions.

Q3. On an educational trip to Uttaranchal, Ketki and her friends observe that many local people were having swollen necks. Please help Ketki and her friends to find out the solutions to the following questions.
a. Which probable disease are these people suffering from?
b. How is it caused?
c. What effect does this condition have on pregnancy?

Answer: a. Goitre. This is due to the overstimulation of thyroid gland which causes an enlargement in the gland.
b. It is caused due to the deficiency of iodine in the diet that results in hyperthyroidism and enlargement of the thyroid gland
c. Defective development and maturation of the growing baby leads to stunted growth (cretinism)

Q4. George comes on a vacation to India from US. The long journey disturbs his biological system and he suffers from jet lag. What is the cause of his discomfort?

Answer: George comes on a vacation to India from US. The long journey disturbs his biological system and he suffers from jet lag. It is due to the disturbance in diurnal rhythm. Melatonin plays a very important role in the regulation of a 24-hour (diurnal) rhythm of our body. For example, it helps in maintaining the normal rhythms of sleep-wake cycle, body temperature.

Q5. Inflammatory responses can be controlled by a certain steroid. Name the steroid, its source and also its other important functions.

Answer: Glucocorticoids, particularly cortisol, produces anti-inflammatory reactions and suppresses the immune response. Cortisol stimulates the RBC production. Glucocorticoids stimulate gluconeogenesis, lipolysis and proteolysis; and inhibit cellular uptake and utilisation of amino acids. Cortisol is also involved in maintaining the cardio-vascular system as well as the kidney functions.

Q6. Old people have weak immune system. What could be the reason?

Answer: Thymus is degenerated in old individual resulting in a decreased production of thymosins. As a result the immune responses of old persons become weak.

Q7. What are the effects of hypothyroidism (observed during pregnancy) on the development and maturation of a growing baby?

Answer: Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf-mutism, etc.

Q8. Mention the difference between hypothyroidism and hyperthyroidism.

Answer:  Iodine is essential for the normal rate of hormone synthesis in the thyroid. Deficiency of iodine in our diet results in hypothyroidism and enlargement of the thyroid gland, commonly called goitre. Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf-mutism, etc. In adult women, hypothyroidism may cause menstrual cycle to become irregular. Due to cancer of the thyroid gland or due to development of nodules of the thyroid glands, the rate of synthesis and secretion of the thyroid hormones is increased to abnormal high levels leading to a condition called hyperthyroidism which adversely affects the body physiology.

Q9. You have learnt that a characteristic feature of endocrine system is the presence of feed back loops. By this what is meant if hormone A stimulates gland ‘ \(X\) ‘ to secrete hormone B , the production of ‘ A ‘ could be modified when the level of B changes in our blood. An example is the relation between hormones LH and estrogen ( \(\mathrm{E}_2\) ). An old woman exhibits the following features. High levels of LH in blood but low levels of \(\mathrm{E}_2\) in the blood. Another woman exhibits high level of LH in blood and also high level of \(\mathrm{E}_2\) in the blood. Where is the defect in both these women? Provide suitable diagram to support this answer.

Answer: If an old woman exhibits the high levels of LH in blood but low levels of \(E_2\) in the blood then it may be due to any abnormality in the anterior pituitary. If an old woman exhibits the high levels of LH in blood and high levels of \(E_2\) in the blood then it may be due to any abnormality in the anterior pituitary or ovary.

LONG ANSWER TYPE QUESTIONS

Q1. A milkman is very upset one morning as his cow refuses to give any milk. The milkman’s wife gets the calf from the shed. On fondling by the calf, the cow gave sufficient milk. Describe the role of endocrine gland and pathway associated with this response?

Answer: Oxytocin hormone is the hormone which stimulates the release of milk from the mammary gland by causing surrounding cells to contract. When the infant starts feeding breast stimulates the posterior pituitary to produce the oxytocin hormone and oxytocin hormone stimulates the milk secretion. It also contracts the smooth muscles of the uterus to expel the foetus outside the body of the mother.

Q2. A sample of urine was diagnosed to contain high content of glucose and ketone bodies. Based on this observation, answer the following:
a. Which endocrine gland and hormone is related to this condition?
b. Name the cells on which this hormone acts.
c. What is the condition called and how can it be rectified?

Answer: a. The pancreas is the gland and homone is Insulin which is responsible for this condition.
b. Hepatocytes and adipocytes cells are the main cells on which insulin act. Insulin allows muscles, liver and fat cells to take up this glucose.
c. This condition causes diabetes mellitus. Diabetes mellitus is a condition in which the body does not produce enough insulin hormone which results in a high level of sugar in the blood. It can be controlled by maintaining cholesterol, glucose level and blood pressure to the normal level.

Q3. Calcium plays a very important role in the formation of bones. Write on the role of endocrine glands and hormones responsible for maintaining Calcium homeostasis.

Answer: Thyroid gland and the parathyroid gland that is an antagonist with each other are responsible for maintaining calcium homeostasis. Calcitonin is responsible for the high calcium level in the blood. It also decreases plasma calcium concentration by decreasing mobilization of calcium from bones. Parathyroid hormone increases the calcium level in blood which is secreted by the parathyroid gland. It increases the reabsorption of calcium by renal tubules of the kidney.

Q4. Illustrate the differences between the mechanism of action of a protein and a steroid hormone.

Answer: Protein hormone:
Protein hormones are insulin, glucagon, prolactin etc. They have to bind their receptors which are present on the plasma membrane. They form their homone receptor complex on the membrane. They are water-soluble hormone so they can’t diffuse to lipid layer plasma membrane and bind to a receptor on membrane.
Steroid hormone:
Steroid hormone is an androgen, estrogen etc. which don’t have their receptor on plasma membrane they directly diffuse to their target site. They don’t produce a secondary messenger.

Q5. Hypothalamus is a super master endocrine gland. Elaborate.

Answer:Hypothalamus is a very small but extremely important pad of the diencephalon that is involved in the mediation of endocrine, autonomic and behavioural function. It contains several groups of neurosecretory cells called nuclei which produce hormones. Hypothalamus provides anatomical connection between the nervous and endocrine system. Hypothalamus is a super master endocrine gland as it secretes hormones that regulate the synthesis and secretion of the pituitary gland which is the master gland. It is connected to the anterior lobe of the pituitary gland by hypo physical portal veins. The hormones which are secreted by hypothalamus are:

• Adrenocorticotrophic releasing hormone (ARH) or corticotrophin: It stimulates the anterior lobe of pituitary gland to secrete Adrenocorticotropic Hormone (ACTH). ACTH stimulates the synthesis and secretion of steroid hormones called glucocorticoids by adrenal glands.
• Growth hormone-releasing hormone (GHRH):  It stimulates the anterior lobe of the pituitary gland to release growth hormone or somatostatin.
• Thyrotropin-releasing hormone (TRH): It stimulates the anterior lobe of pituitary gland to release Thyroid Stimulating Hormone (TSH).
• Growth hormone inhibitory hormone (GHIH): Somatostatin, also known as growth hormone-inhibiting hormone (GHIH) or by several other names, is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones. Somatostatin inhibits insulin and glucagon secretion.
• Gonadotropin-releasing hormone (GnRH): It is a highly conserved neuroendocrine decapeptide that is essential for the onset of puberty and the maintenance of the reproductive state. First identified in mammals, the GnRH signaling pathway is found in all classes of vertebrates; homologues of GnRH have also been identified in invertebrates.
• Prolactin inhibitory hormone (PIH): In a non-pregnant woman, prolactin secretion is inhibited by prolactin–inhibiting hormone (PIH), which is actually the neurotransmitter dopamine, released from neurons in the hypothalamus.
• Prolactin Releasing hormone (PRH): It stimulates the anterior lobe of the pituitary gland to secrete prolactin.
• MSH releasing hormone (MSHRH): It stimulates the intermediate lobe of the pituitary gland to secrete Melanocyte Stimulating Hormone (MSH). These hormones released from hypothalamus are involved in the process like temperature regulation, control of water balance in body, sexual behaviour and reproduction control daily cycles in physiological state, behaviour and mediation of emotional responses. is called as super master endocrine gland of body.
• MSH Inhibitory hormone (MSHIH): MSH Release-Inhibiting Hormone A hypothalamic tripeptide, enzymatic degradation product of OXYTOCIN, that inhibits the release of MELANOCYTE-STIMULATING HORMONES.