I. Introduction A. Chemical regulation in the body is performed by chemicals called hormones 1. Hormones are complex chemicals that have many different effects 2. They are usually produced in one part of the body, and they may have effects on other parts of the body that are a long distance from where they are produced 3. They are secreted mainly by organs called endocrine glands 4.
Hormones travel in the bloodstream to cells that are called target cells a.
These are cells that respond to the hormone B. Endocrine system is closely linked to the nervous system 1. Another type of hormone-secreting cell is called a neurosecretory cell a. This is a specialized nerve cell that conducts nerve impulses and secretes hormones 2. The endocrine system, then, is a communication and control system, like the nervous system 1. It has very close physiological and anatomical connections to the nervous system 2.