The endocrine (endo, meaning within, and crine, meaning to secrete) system includes the organs of the body that secrete hormones directly into body fluids such as blood. Hormones help to regulate the chemical reactions within cells. They therefore control the functions of the organs, tissues, and other cells that comprise these cells. In this chapter you will learn about the processes and organs of the endocrine system. See Figure 341 for an illustration of the organs of the endocrine system, as well as the heart and kidney, both of which secrete a hormone, although hormone secretion is not the primary function of either of them.

Outline

• Hormones
• Negative and Positive Feedback Loops
• The Hypothalamus
• The Pituitary Gland
• The Thyroid Gland and Parathyroid Glands
• The Adrenal Glands
• The Pancreas
• Other Hormone-Producing Organs
• The Stress Response

Learning Outcomes

After completing Chapter 34, you will be able to:

Summary

The endocrine system regulates all chemical reactions in cells. The substances responsible for this regulation are known as hormones. Hormones are produced by endocrine glands. They are released directly into the affected tissues or into the bloodstream to create a response. The major endocrine glands are the hypothalamus, pituitary, pineal body, thyroid, parathyroid, thymus, adrenals, and pancreas. An understanding of this system can help medical assistants be aware of the signs and symptoms of common endocrine system disorders and to be more effective when helping patients learn about the advantages and disadvantages of hormone replacement therapy.