The endocrine system is made up of glands that release hormones directly into the bloodstream, rather than through ducts. These hormones act as chemical messengers that travel throughout the body and influence target cells that have receptors for specific hormones. Key components of the endocrine system include hormones, target cells, endocrine glands that release hormones into the bloodstream, and feedback mechanisms that help regulate the system and maintain homeostasis.

1. 39.1 The Endocrine System

2. Hormone Substance produced in one part of an organism that affects another part of the same organism.

3. Target CellCell that has a receptor for a particular hormone.

4. Exocrine Gland Gland that releases its secretions through tubelike structures called ducts.

5. Endocrine GlandGland that releases its secretions directly into the bloodstream.

6. Prostaglandin Hormonelike modified fatty acid produced by a wide range of cells; generally affects only nearby cells and tissues.

7. Key ConceptThe Endocrine system is made up of glands that release their products into the bloodstream. These products deliver messages throughout the body.

8. Key ConceptLike most systems of the body, the endocrine system is regulated by feedback mechanisms that function to maintain homeostasis.