What is the Difference Between Direct and Indirect Hormone Action?

The difference between direct and indirect hormone action lies in the mechanism through which hormones exert their effects on target cells and tissues. There are two types of hormone actions:

1. Direct hormone action: In this type of action, hormones directly bind to specific receptors on target cells and tissues, stimulating the target cell's response. Direct hormone action is responsible for the main function of a hormone. Examples of hormones that act directly on non-endocrine tissues include prolactin, ADH, and oxytocin.
2. Indirect hormone action: In this type of action, hormones modulate the secretion of other hormones by stimulating other glands. This action is also known as trophic hormone action, as it involves the release of hormones such as TSH, ACTH, FSH, and LH, which regulate the secretory activity of other glands. Indirect action of hormones always facilitates the direct action of hormones.

In summary, the key difference between direct and indirect hormone action is that direct hormone action occurs when hormones directly bind to target cells and stimulate their response, while indirect hormone action involves the modulation of other glands to secrete hormones.

Comparative Table: Direct vs Indirect Hormone Action

Direct and indirect hormone actions are two types of mechanisms through which hormones exert their effects on target cells and tissues. Here is a table summarizing the differences between direct and indirect hormone action:

In direct hormone action, hormones bind directly to receptors on target cells and regulate the target cell's response. On the other hand, in indirect hormone action, hormones modulate the secretion of other glands to secrete hormones, thus affecting the target cells and tissues.