A collection of glands found throughout the body that manufacture and secrete hormones into the bloodstream in order to effect behavioral change or maintain normal bodily functions is called the system.

The Endocrine System.

Explanation:

The endocrine system is composed of various endocrine glands and like other glands, they release(secrete) useful substances. Some exocrine glands deliver their secretion via ducts, but endocrine does theirs through hormones. These hormones which are chemical substances are secreted in response to various stimuli(both internal and external). They target their effects on certain organs known as target organs.

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.