Test Your Knowledge

The endocrine system is a network of glands that plays a vital role in a wide variety of bodily functions. The glands of this system produce and secrete hormones that control the following processes:

• Growth and development
• Internal balance of bodily systems (homeostasis)
• Metabolism
• Regulation of mood and energy levels
• Responses to surroundings, stress and injury
• Sexual function and reproduction
• Tissue function

The endocrine system specializes in processes of the body that occur gradually, whereas the nervous system generally directs faster processes, such as breathing and body movements. However, in many cases the endocrine system and nervous system work together to guide some body processes.

Glands and hormones are the primary features of the endocrine system. Glands are collections of cells that produce and secrete substances called hormones that act as chemical messengers in the body. Glands that do not make hormones, such as sweat glands, salivary glands and the prostate gland, are not part of the endocrine system. Hormones move information and instructions from one group of cells to another.

Imbalances in the endocrine system can cause problems. Too much or too little of a hormone, trouble with the receptor sites, trouble with the feedback system or regulating system, glandular problems, or problems with the blood supply can throw the whole system out of balance. This creates problems in the body on a glandular or functional level. For this reason, the chemicals of the endocrine system must be kept in precise balance. Imbalances can lead to systemic dysfunctions and disorders that affect body functions necessary for sustaining life.

Some endocrine diseases are autoimmune conditions, meaning the body’s immune system mistakenly identifies healthy tissues as a threat and attacks them. Examples include type 1 diabetes, Hashimoto’s thyroiditis, Graves’ disease and Addison disease. Some endocrine disorders involve more than one gland, such as autoimmune polyglandular syndrome.

Some endocrine conditions involve benign (noncancerous) tumors, such as thyroid nodules and insulinoma. In rare cases, cancer can develop in the endocrine glands.

Physicians have many ways of assessing endocrine function and diagnosing endocrine disorders, including glucose tests, thyroid blood tests, other blood tests, a physical examination, urine tests, ultrasound and thyroid imaging tests. A primary care physician will typically refer a patient with an endocrine condition to an endocrinologist.