Here's why:

* Glands: The endocrine system is composed of glands that secrete hormones directly into the bloodstream. These hormones act as chemical messengers, traveling throughout the body to regulate various bodily functions.

* Hormones: Hormones are responsible for regulating important processes like growth, metabolism, mood, and reproduction. They exert their effects on specific target cells that have receptors for them.

* Examples of endocrine glands: Some major endocrine glands include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries (in females), and testes (in males).

Let me know if you have any more questions about the endocrine system!