Question

Endocrine gland that functions as biological clock and a neurosecretory transducer is __________.

• A. Adrenal gland
• B. Thyroid gland
• C. Thymus gland
• D. Pineal gland

Answer 1

Answer: (D)

Pineal gland

A. Adrenal gland is present on upper side of kidneys and has two parts, adrenal cortex which secrete glucocorticoids, mineralocorticoids and sexocorticoids and adrenal medulla which secrete adrenaline and nor-adrenaline hormone.

B. Thyroid gland is situated between the trachea and larynx in the neck and secretes thyroxine hormone which increases oxygen consumption by metabolically active tissues.

C. Thymus gland is associated with the development of immune system and present on the dorsal side of heart. It secretes thymosin hormone which plays an important role in the differentiation of T-lymphocytes.

D. Pineal gland is a small, rounded and reddish brown gland present at the dorsal side of forebrain. This gland secretes melatonin and serotonin hormones. Melatonin is derived from amino acid tryptophan and secreted from pineal gland. It regulates the 24 hour rhythm of our body like sleep-wake cycle, temperature etc. and also affects metabolism and pigmentation.

So, the correct answer is 'Pineal gland'.