Endocrine and Metabolic Disorders

Insulin regulates blood glucose by promoting cellular glucose uptake and storage. Iodine is for thyroid function, hemoglobin carries oxygen, and glycogen is stored glucose (not a regulator). Insulin lowers blood sugar, while glucagon raises it - together they maintain glucose homeostasis.

As per immunity theory, disappearance of thymus gland results in ageing.

Diabetes is caused by problems with insulin - either deficiency (Type 1 diabetes) or the body's cells becoming resistant to insulin (Type 2). Insulin is a hormone that regulates blood sugar levels. Iodine deficiency causes thyroid problems, not diabetes.

Addison's disease occurs when the adrenal cortex is destroyed or dysfunctional, leading to deficient secretion of glucocorticoids and mineralocorticoids. This causes fatigue, low blood pressure, and electrolyte imbalances. Option A correctly identifies the adrenal hyposecretion as the root cause.

Simmond's disease (panhypopituitarism) results from pituitary destruction, causing deficiency of all pituitary hormones. This leads to myxoedema - thickened, dry skin from thyroid hormone deficiency, among other symptoms. Option D correctly identifies this association.

Parathormone (PTH) from the parathyroid glands increases blood calcium by stimulating bone resorption, kidney calcium reabsorption, and vitamin D activation. This directly opposes calcitonin. Option B correctly identifies PTH as the calcium-raising hormone.

Cushing's syndrome results from excessive cortisol production (hypercortisolism) from the adrenal cortex. This can be due to adrenal tumors, pituitary ACTH-secreting tumors, or exogenous corticosteroid administration. Symptoms include weight gain, moon face, buffalo hump, and hyperglycemia. Decreased cortisol would cause Addison's disease, not Cushing's.

Thyroxine is a metabolic stimulant - it increases tissue metabolism, oxygen consumption, pulmonary ventilation, and basal metabolic rate. "Depression of metabolism" means a decrease in metabolic rate, which is the opposite of what thyroxine does. Therefore, depression of metabolism is NOT caused by thyroxine.

Goitre (thyroid enlargement) has multiple causes: iodine deficiency prevents thyroxine synthesis, increased TSH production stimulates thyroid growth, and increased thyroxine production can also cause enlargement. All listed mechanisms independently cause goitre.

Thyroxine is an iodinated hormone - it contains iodine atoms in its molecular structure. This is why iodine is essential for thyroid function. Thyroxine does not inhibit or stimulate iodine compound synthesis in the body.

Thyroxine controls metamorphosis timing in frogs. Excess thyroxine accelerates development, causing earlier metamorphosis. Too little thyroxine delays or prevents metamorphosis. This is a key example of hormonal timing control.

Epinephrine, thyroxine, and glucagon are all hyperglycemic hormones that increase blood glucose levels. Epinephrine stimulates glycogenolysis, thyroxine increases metabolic rate and gluconeogenesis, and glucagon directly promotes glucose production. Aldosterone is a mineralocorticoid that regulates sodium and potassium balance in the kidneys, but does not affect blood glucose levels directly.

Insulin is a hormone produced by the pancreas that regulates blood sugar levels. The lack of insulin or insulin resistance leads to diabetes mellitus, where the body cannot properly process glucose. Hepatitis, sinusitis, and meningitis are inflammatory conditions affecting the liver, sinuses, and brain membranes respectively, and are not related to insulin deficiency.

Correct answer. A is correct and R is incorrect. Hyposecretion of somatotropin hormone (STH) causes Simond’s disease. STH is secreted by anterior lobe of pitutary.