The Endocrine system, consists of a series of glands that secrete hormones into the bloodstream that regulate bodily functions. The Endocrine glands, any ductless glands, such as the adrenal gland, pineal gland, thyroid, parathyroid, testes, ovaries, pituitary and thymus, who's secreted hormones (such a adrenaline) pass directly into the body to regulate homeostasis.
The image above shows a more detailed view of the endocrine glands.
PubMed:http://www.ncbi.nlm.nih.gov/pubmed/24653858
Sources: Fishbein, Morris. The New Illustrated Medical and Health Encyclopedia.
New York: H. S. Stuttman, 1970. Print.
New York: H. S. Stuttman, 1970. Print.