Here's why:

* Steroid hormones are a type of lipid derived from cholesterol. They are produced by the adrenal glands, gonads, and placenta.

* They travel through the bloodstream and bind to specific receptors on target cells, triggering various cellular responses.

* Some examples of steroid hormones include:

* Estrogen and progesterone: Involved in female reproductive development and function.

* Testosterone: Involved in male reproductive development and function.

* Cortisol: Involved in stress response and glucose metabolism.

* Aldosterone: Regulates blood pressure and electrolyte balance.

While other lipids like prostaglandins also act as chemical messengers, they are primarily involved in local signaling, not as widespread as steroid hormones.