What term describes chemical messengers produced by endocrine glands that travel through the bloodstream?

The term that describes chemical messengers produced by endocrine glands that travel through the bloodstream is hormones. Hormones are specialized molecules that play a critical role in regulating various physiological processes in the body, such as metabolism, growth, reproduction, and mood. They are released into the bloodstream by endocrine glands and can affect distant target organs and tissues throughout the body.

In contrast, neurotransmitters are chemical messengers used by the nervous system to transmit signals across synapses between nerve cells, rather than through the bloodstream. Enzymes are biological catalysts that speed up chemical reactions but are not involved in signaling between different parts of the body. Proteins, while important macromolecules involved in a variety of functions, are a broader category that includes enzymes and structural components, not specifically related to the role of signaling like hormones. Therefore, hormones are the correct choice as they specifically encompass the function of chemical messengers traveling through the bloodstream from endocrine sources.