Question

What is the role of the second messenger in hormone action?

Answer 1

Mechanism of hormonal action:

Hormones function by binding to their receptors which are located on the target site, to form the hormone receptor complex. The receptors are usually located either on the plasma membrane (membrane receptors) of the targets or inside the cell as in nucleus (intracellular receptors).

Role of the secondary messengers:

The protein hormones are not lipid soluble and are unable to penetrate through the plasma membrane which is composed of phospholipid bilayer. Hence, these bind to the receptors present on the plasma membrane forming a hormone receptor complex. This binding generates other molecules like $C{a}^{++}$ , cAMP etc. which act as secondary messengers. These secondary messengers drive a cascade of biochemical reactions and physiological changes in the target cell.