Here's why:

* The circulatory system is the body's transportation network: The blood vessels act like highways, carrying hormones from their source (glands) to all parts of the body.

* Specificity: Hormones are highly specific. They only bind to and affect certain cells that have receptors designed for that particular hormone.

* Distance: Many endocrine glands (the glands that produce hormones) are located far from their target cells. The bloodstream allows hormones to travel the necessary distances to reach their destinations.

Let me know if you have any other questions!