The endocrine system is comprised of a number of glands that release chemical messengers known as "hormones" into the "bloodstream". To solve this problem, you should first think to yourself, "What does the endocrine system do? What are the pathways of this system?" This will help you think critically to find the answer. The endocrine system is the collection of glands that secretes hormones in your bloodstream to reach other organs in the organism.