The Endocrine System
Endocrine organs are sometimes called ductless glands because they have no ducts connecting them to specific body parts. The hormones they secrete are released directly into the bloodstream. In contrast, the exocrine glands, such as the sweat glands or the salivary glands, release their secretions directly to target areasfor example, the skin or the inside of the mouth. Some of the body's glands are described as Endo-exocrine glands because they secrete hormones as well as other types of substances. Even some nonglandular tissues produce hormone-like substancesnerve cells produce chemical messengers called neurotransmitters, for example.
The earliest reference to the endocrine system comes from ancient Greece, in about 400 BC. However, it was not until the 16th century that accurate anatomical descriptions of many of the endocrine organs were published. Research during the 20th century has vastly improved our understanding of hormones and how they function in the body. Today, endocrinology, the study of the endocrine glands, is an important branch of modern medicine. Endocrinologists are medical doctors who specialize in researching and treating disorders and diseases of the endocrine system. COMPONENTS OF THE ENDOCRINE SYSTEM
The primary glands that make up the human endocrine system are the hypothalamus, pituitary, thyroid, parathyroid, adrenal, pineal body, and reproductive glandsthe