The Endocrine System

Step 1: Understanding the relationship between hormones and disorders
Each hormone is secreted by a specific gland and plays a role in physiological processes. The given table includes information about hormone-gland pairs and their associated disorders.
Step 2: Analyzing the given combinations
- Somatotropin (Growth Hormone) - Pituitary Gland - Acromegaly: Correct. Excess secretion of somatotropin results in acromegaly.
- Vasopressin - Pituitary Gland - Diabetes Mellitus: Incorrect. Vasopressin (also called ADH) is linked to diabetes insipidus, not diabetes mellitus.
- Glucocorticoids - Adrenal Glands - Addison’s Disease: Correct. Hyposecretion of glucocorticoids leads to Addison’s disease.
- Calcitonin - Parathyroid Glands - Cretinism: Incorrect. Calcitonin is secreted by the thyroid gland, and cretinism is caused by thyroid hormone deficiency.
Step 3: Selecting the correct pairs
From the analysis, the correct combinations are I and III, which match option (A).

Step 1: Match Hormones to Functions:

• A. Melatonin: Secreted by the Pineal gland. Regulates the diurnal (24-hour) rhythm of the body, i.e., the Sleep-wake cycle (III).
• B. Thyroxine ( ): Secreted by the Thyroid. Its primary function is regulating the Basal Metabolic Rate (BMR) (I) and body metabolism.
• C. Aldosterone: A mineralocorticoid from the Adrenal cortex. It acts on renal tubules to reabsorb and water, maintaining Water-electrolyte balance (IV).
• D. Glucagon: Secreted by Alpha cells of Islets of Langerhans. It stimulates glycogenolysis and gluconeogenesis, increasing blood sugar, causing Hyperglycemia (II).

Step 2: Sequence:
A - III, B - I, C - IV, D - II. Matches Option (A).

Step 1: Analyze the Function of Insulin:
Insulin is a hormone that lowers blood glucose levels (Hypoglycemic factor) by promoting glucose uptake by cells and glycogenesis.
Step 2: Analyze Hypersecretion (Assertion):
If insulin is secreted in excess (Hypersecretion), blood glucose levels drop drastically. This condition is called severe Hypoglycemia. The brain relies almost exclusively on glucose; a sudden drop deprives neurons of energy, leading to loss of consciousness and convulsions, termed Insulin Shock. Thus, Assertion (A) is true.
Step 3: Analyze Reason (R):
Hypoglycemia means low blood sugar. This is the direct physiological result of insulin hypersecretion and is the specific cause of the shock state. Therefore, (R) is true and correctly explains why the shock occurs.

• Thymosins are hormones/peptides produced by the thymus that are involved in maturation and differentiation of T-lymphocytes (thymic education).
• Differentiation and maturation of T-cells strengthen cellular immunity; thus R directly explains A.
• Therefore the correct choice is (1) Both (A) and (R) are true, (R) is the correct explanation of (A).

The hypothalamus regulates endocrine activities by secreting releasing and inhibiting hormones which act directly on the anterior pituitary. These hormones control secretion of pituitary hormones, making the hypothalamus the master control centre. Both Assertion and Reason are true and Reason correctly explains the Assertion.

• Prolactin is secreted by the anterior pituitary (A → V).
• Progesterone is produced mainly by the corpus luteum after ovulation (B → III).
• Melatonin is secreted by the pineal gland (C → I).
• Calcitonin is produced by the parafollicular C-cells of the thyroid gland (D → II).
• Therefore the correct matching is (4) A-V, B-III, C-I, D-II.

Acromegaly: excess somatotropin (growth hormone) in adults; Cretinism: deficiency of thyroxine during infancy; Diabetes insipidus: lack of vasopressin (ADH); Cushing’s syndrome: excess cortisol from adrenal cortex. Matching is based on hormone-disorder relationships.