What are hormone ? Mention one function each for (i) ACTH (ii) Melatonin (iii) Parathyroid hormone (iv) Thymosin.

Explanation

Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts.
(i) Adrenocorticotrophic hormone : ACTH stimulates the synthesis and secrelion of steroid hormones called glucocorticoids from the adrenal cortex.
(ii). Melatonin : Melatonin plays a very important role in the regulation of a 24-hour (diurnal) rhythm of our body.
(iii). Parathyroid hormone : Parathyroid hormones increases the `Ca^(2+)` levels in the blood. Parathyroid hormone acts on bones and stimulates the process of bone resorption/ dissolution demineralization.
(iv) Thymosin : Thymosin plays a major role in the differentiation of T-Lymphocytes which provide cell-mediated immunity.