Video narration
How can a tiny chemical signal change what distant parts of your body do? Think of a text message: it carries a signal toward someone meant to receive it. In your endocrine system, glands release hormones-chemical messages-into your blood. The bloodstream carries them throughout your body, past many kinds of cells. But travel alone doesn't make a cell respond. Only a cell with the matching receptor, a fitting receiver, can pick up that hormone's message. That match changes what the cell does, and those changes can shape body functions. As conditions shift, feedback helps adjust how much hormone a gland releases. The details vary from one hormone to another, but this adjustment helps keep your body stable. So distant parts of your body respond when glands release hormones into the blood and matching cells receive them; feedback helps tune the release.