Question 3.
List the hormones secreted by the following:

1. Hypothalamus
2. Pituitary
3. Thyroid
4. Parathyroid
5. Adrenal
6. Pancreas
7. Testis
8. Ovary
9. Thymus
10. Atrium
11. Kidney
12. G-I Tract

Answer:
(a) Hypothalamus:

• Releasing hormones (e.g., Gonadotrophin Releasing Hormone – GnRH)
• Inhibiting hormones (e.g., Somatostatin)

(b) Pituitary gland:
Anterior pituitary (Adenohypophysis):

• Growth Hormone (GH)
• Prolactin (PRL)
• Thyroid Stimulating Hormone (TSH)
• Adrenocorticotrophic Hormone (ACTH)
• Luteinizing Hormone (LH)
• Follicle Stimulating Hormone (FSH)
• Melanocyte Stimulating Hormone (MSH)

Posterior pituitary (Neurohypophysis):

• Oxytocin
• Vasopressin or Antidiuretic Hormone (ADH)

(c) Thyroid gland:

• Thyroxine (T₄)
• Triiodothyronine (T₃)
• Thyrocalcitonin (TCT)

(d) Parathyroid gland:

• Parathyroid Hormone (PTH)

(e) Adrenal gland:
Adrenal medulla:

• Adrenaline (Epinephrine)
• Noradrenaline (Norepinephrine)

Adrenal cortex:

• Glucocorticoids (e.g., Cortisol)
• Mineralocorticoids (e.g., Aldosterone)
• Small amounts of Androgenic steroids

(f) Pancreas (Islets of Langerhans):

• Insulin (from β-cells)
• Glucagon (from α-cells)

(g) Testis:

• Androgens (mainly Testosterone)

(h) Ovary:

• Estrogen
• Progesterone

(i) Thymus:

• Thymosins

(j) Atrium (Heart):

• Atrial Natriuretic Factor (ANF)

(k) Kidney:

• Erythropoietin

(l) Gastro-Intestinal (G-I) Tract:

• Gastrin
• Secretin
• Cholecystokinin (CCK)
• Gastric Inhibitory Peptide (GIP)

Question 4.
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) Pituitary
(b) Thyroid
(c) Adrenal Cortex
(d) Testis and Ovaries
(e) Pineal gland

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

• Parathyroid hormone (PTH)
• Thyroid hormones
• Thymosins
• Androgens
• Estrogens
• Insulin and Glucagon

Answer:
(a) Parathyroid Hormone (PTH):

• Secreted by the parathyroid glands.
• Increases the calcium (Ca²⁺) level in the blood (hypercalcemic hormone).
• Stimulates bone resorption (release of Ca²⁺ from bones).
• Enhances reabsorption of Ca²⁺ from renal tubules.
• Promotes absorption of Ca²⁺ from the intestine.
• Works in coordination with thyrocalcitonin (TCT) to maintain calcium balance in the body.

(b) Thyroid Hormones (T₃ and T₄):

• Regulate basal metabolic rate (BMR) and energy metabolism.
• Control the metabolism of carbohydrates, proteins, and fats.
• Essential for growth and development of the body, especially the brain and nervous system.
• Support red blood cell formation (erythropoiesis).
• Maintain water and electrolyte balance.
• Thyrocalcitonin (TCT) helps reduce blood calcium levels.

(c) Thymosins:

• Secreted by the thymus gland.
• Promote the differentiation of T-lymphocytes, providing cell-mediated immunity.
• Stimulate the production of antibodies, aiding humoral immunity.
• Important in the development and maintenance of the immune system.

(d) Androgens:

• Secreted by Leydig (interstitial) cells in the testis.
• Main androgen: Testosterone.
• Promote development and functioning of male accessory sex organs.
• Responsible for secondary sexual characters in males (e.g., beard, deep voice, muscular growth).
• Stimulate spermatogenesis (formation of sperm).
• Influence male sexual behaviour (libido) and have anabolic effects on protein and carbohydrate metabolism.

(e) Estrogens:

• Secreted mainly by growing ovarian follicles in females.

• Stimulate growth and functioning of female reproductive organs.
• Responsible for female secondary sexual characters (e.g., high-pitched voice, breast development).
• Promote growth of ovarian follicles and regulate the menstrual cycle.
• Influence female sexual behaviour and mammary gland development.

(f) Insulin and Glucagon:

Insulin:

• Secreted by β-cells of the Islets of Langerhans (pancreas).
• Lowers blood glucose level (hypoglycemic hormone).
• Promotes glucose uptake and utilization by body cells.
• Stimulates glycogenesis (conversion of glucose to glycogen) in the liver and muscles.

Glucagon:

• Secreted by α-cells of the Islets of Langerhans.
• Raises blood glucose level (hyperglycemic hormone).
• Stimulates glycogenolysis (breakdown of glycogen to glucose) and gluconeogenesis (formation of glucose from non-carbohydrate sources).

Together, insulin and glucagon maintain blood glucose homeostasis.

Question 6.
Give example(s) of:

• Hyperglycemic hormone and hypoglycemic hormone
• Hypercalcemic hormone
• Gonadotrophic hormones
• Progestational hormone
• Blood pressure lowering hormone
• Androgens and estrogens

Answer:
(a) Hyperglycemic hormone: Glucagon. Hypoglycemic hormone: Insulin.
(b) Hypercalcemic hormone: Parathyroid hormone (PTH).
(c) Gonadotrophic hormones: Follicle Stimulating Hormone (FSH) or Luteinizing Hormone (LH).
(d) Progestational hormone: Progesterone.
(e) Blood pressure lowering hormone: Atrial Natriuretic Factor (ANF).
(f) Androgen: Testosterone. Estrogens: Estrone, Estradiol, Estrol.

Question 7.
Which hormonal deficiency is responsible for the following:

(a) Diabetes mellitus

(b) Goitre

(c) Cretinism
Answer:
(a) Insulin
(b) Thyroxine
(c) Thyroxine

Question 8.
Briefly mention the mechanism of action of FSH,
Answer:

• Follicle Stimulating Hormone (FSH) is a peptide hormone secreted by the anterior pituitary gland.
• Being a water-soluble hormone, it cannot enter the target cell directly.
• FSH binds to specific receptor proteins present on the cell membrane of the target cell (ovarian follicles in females and Sertoli cells in males).
• This activates the enzyme adenylate cyclase, which converts ATP into cyclic AMP (cAMP).
• The cAMP acts as a second messenger, triggering a cascade of biochemical reactions inside the cell.
• These reactions stimulate growth and maturation of ovarian follicles in females and spermatogenesis in males.

Question 9.
Match the following:

          Column I                                                Column II

        (a) T                                                         (i) Hypothalamus

        (b) PTH                                                   (ii) Thyroid

        (c) GnRH                                                (iii) Pituitary

        (d) LH                                                     (iv) Parathyroid

Answer:
(a) T → Thyroid
(b) PTH → Parathyroid
(c) GnRH → Hypothalamus
(d) LH → Pituitary

Additional Questions And Answers

Question 1.
What is the difference between endocrine glands and exocrine glands?
Answer:

Question 2.
What is the role of hypothalamus in endocrine control?
Answer:

• The hypothalamus controls the pituitary gland, also called the master gland.
• It secretes releasing hormones (RH) and inhibiting hormones (IH).

• • For example:

• TRH – Thyrotropin Releasing Hormone
• CRH – Corticotropin Releasing Hormone
• GnRH – Gonadotropin Releasing Hormone

• Thus, it regulates secretion of hormones from the pituitary and maintains homeostasis.

Question 3.
Name the hormones secreted by the adrenal cortex and mention one function of each.
Answer:

Question 4.
What are the effects of insulin deficiency?
Answer:

• Deficiency of insulin causes Diabetes mellitus.
• Leads to increased blood glucose level (hyperglycemia).
• Glucose appears in urine (glycosuria).
• Causes frequent urination, thirst, weakness, and weight loss.

Question 5.
What is the function of melatonin?
Answer:

• Secreted by the pineal gland.
• Regulates sleep–wake cycle (circadian rhythm).
• Influences body temperature, metabolism, and mood.
• Helps maintain biological rhythms of the body.

Question 6.
Differentiate between diabetes mellitus and diabetes insipidus.
Answer:

Question 7.
Name the hormones involved in calcium regulation.
Answer:

1. Parathyroid Hormone (PTH) – Increases blood calcium level.
2. Thyrocalcitonin (TCT) – Decreases blood calcium level.
3. Vitamin D (Calcitriol) – Enhances absorption of calcium from the intestine.

Together, they maintain calcium homeostasis in the body.

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