A substance directly involved in cellular communication within the human body

Hormones

The endocrine system is made of endocrine glands and exocrine glands which are responsible for taking the hormones released by the system to the target organs. The difference between them is that the exoocrine glands release hormones in specific areas for example the sweat glands are especially active in the armpits. The endocrine glands on the other hand release hormones directly into the bloodstream and when the blood travels to all parts of the body, it provides the organs with the hormones they need.