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Endocrine Glands and Cells
The endocrine system consists of cells, tissues, and organs that secrete hormones as a primary or secondary function. The endocrine gland is the major player in this system. The primary function of these ductless glands is to secrete their hormones directly into the surrounding fluid. The interstitial fluid and the blood vessels then transport the hormones throughout the body. The endocrine system includes the pituitary, thyroid, parathyroid, adrenal, and pineal glands (Figure \(\PageIndex{1}\)). Some of these glands have both endocrine and non-endocrine functions. For example, the pancreas contains cells that function in digestion as well as cells that secrete the hormones insulin and glucagon, which regulate blood glucose levels. The hypothalamus, thymus, heart, kidneys, stomach, small intestine, liver, skin, ovaries, and testes are other organs that contain cells with endocrine function. Moreover, adipose tissue has long been known to produce hormones, and recent research has revealed that even bone tissue has endocrine functions.
Figure \(\PageIndex{1}\): Endocrine glands and cells are located throughout the body and play an essential role in homeostasis. Organs that have primary endocrine functions are displayed in this figure. (CC BY 4.0; via OpenStax). Detailed text description of the Figure \(\PageIndex{1}\).
Endocrine glands are ductless and are different from the body’s exocrine glands, which release their secretions through small tubes called ducts. Examples of exocrine glands include the sebaceous, mucous, and sudoriferous (sweat) glands of the skin. The pancreas secretes hormones as part of its endocrine function, but it also has an exocrine function where pancreatic acinar cells secrete digestive enzymes through ducts to help digest food that passes through the lumen of the small intestine.As just noted, the pancreas also has an exocrine function: most of its cells secrete pancreatic juice through the pancreatic and accessory ducts to the lumen of the small intestine.
Career Connection
Endocrinologist
Endocrinology is a specialty in the field of medicine that focuses on the treatment of endocrine system disorders. Endocrinologists—medical doctors who specialize in this field—are experts in treating diseases associated with hormonal systems, ranging from thyroid disease to diabetes mellitus. Endocrine surgeons treat endocrine disease through the removal, or resection, of the affected endocrine gland.
Patients who are referred to endocrinologists may have signs and symptoms or blood test results that suggest excessive or impaired functioning of an endocrine gland or endocrine cells. The endocrinologist may order additional blood tests to determine whether the patient’s hormonal levels are abnormal, or they may stimulate or suppress the function of the suspect endocrine gland and then have blood taken for analysis. Treatment varies according to the diagnosis. Some endocrine disorders, such as type 2 diabetes, may respond to lifestyle changes such as modest weight loss, adoption of a healthy diet, and regular physical activity. Other disorders may require medication, such as hormone replacement, and routine monitoring by the endocrinologist. These include disorders of the pituitary gland that can affect growth and disorders of the thyroid gland that can result in a variety of metabolic problems.
Some patients experience health problems as a result of the normal decline in hormones that can accompany aging. These patients can consult with an endocrinologist to weigh the risks and benefits of hormone replacement therapy intended to boost their natural levels of reproductive hormones.
In addition to treating patients, endocrinologists may be involved in research to improve the understanding of endocrine system disorders and develop new treatments for these diseases.
This page titled 1.4: Structures of the Endocrine System was last modified on Sat, 26 Sep 2026 20:13:33 GMT and is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Lakshmikanta Sengupta and Susmita Sengupta via source content that was edited to the style and standards of the LibreTexts platform.
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