Endocrine System

What is the endocrine system?

Your endocrine system consists of the tissues (mainly glands) that create and release hormones.

Hormones are chemicals that coordinate different functions in your body by carrying messages through your blood to your organs, skin, muscles and other tissues. These signals tell your body what to do and when to do it. Hormones are essential for life and your health.

What is the function of the endocrine system?

The main function of your endocrine system is to release hormones into your blood while continuously monitoring the levels. Hormones deliver their messages by locking into the cells they target so they can relay the message. You have more than 50 different hormones, and they affect nearly all aspects of your health — directly or indirectly. Some examples include:

• Metabolism.
• Homeostasis (constant internal balance), such as blood pressure and blood sugar regulation, fluid (water) and electrolyte balance and body temperature.
• Growth and development.
• Sexual function.
• Reproduction.
• Sleep-wake cycle.
• Mood.

Very small amounts of hormones can trigger significant responses and changes in your body. If your body has too little or too much of a hormone, it affects your health. This often causes noticeable symptoms.

What are the endocrine system organs?

Your endocrine system consists of three types of tissues:

• Endocrine glands.
• Organs.
• Endocrine-related tissues.

Endocrine system glands

Glands are special tissues in your body that create and release substances. Endocrine glands make and release hormones directly into your bloodstream. The endocrine glands in your body from head to toe include:

• Pineal gland: This is a tiny gland in your brain that’s beneath the back part of your corpus callosum. It makes and releases the hormone melatonin.
• Pituitary gland: This is a small, pea-sized gland at the base of your brain below your hypothalamus. It releases eight hormones, some of which trigger other endocrine glands to release hormones.
• Thyroid gland: This is a small, butterfly-shaped gland at the front of your neck under your skin. It releases hormones that help control your metabolism.
• Parathyroid glands: These are four pea-sized glands that are typically behind your thyroid. Sometimes they exist along your esophagus or in your chest (ectopic parathyroid glands). They release parathyroid hormone (PTH), which controls the level of calcium in your blood.
• Adrenal glands: These are small, triangle-shaped glands on top of each of your two kidneys. They release several hormones that manage bodily processes, like metabolism, blood pressure and your stress response.

You have other glands in your body that aren’t endocrine glands, such as sweat glands (a type of exocrine gland).

Endocrine system organs

Certain organs in your body also make and release hormones. An organ is a group of tissues that form a structure that performs specific important functions in your body. The organs that are part of your endocrine system include:

• Hypothalamus: This is a structure deep within your brain (which is an organ). It’s the main link between your endocrine system and your nervous system. It makes two hormones that your pituitary gland stores and releases (oxytocin and vasopressin) and makes and releases two hormones (dopamine and somatostatin).
• Pancreas: This organ is in the back of your abdomen (belly). It’s both an organ and a gland and is also part of your digestive system. It releases two hormones that are essential to maintaining healthy blood sugar levels: insulin and glucagon.
• Adipose tissue (body fat): This is a connective tissue that extends throughout your body. It’s found under your skin (subcutaneous fat), between your internal organs (visceral fat) and in the inner cavities of bones (bone marrow adipose tissue). Adipose tissue releases many different hormones, including leptin, angiotensin and adiponectin.
• Ovaries: These are small, oval-shaped glands located on either side of your uterus. They produce and store your eggs (also called ova) and make sex hormones that control your menstrual cycle and pregnancy.
• Testicles (testes): These are small, round organs underneath your penis in your scrotum. They make sperm and sex hormones, particularly testosterone.

Other tissues that release hormones

Other tissues in your body release hormones. But we don’t typically think of them as endocrine system tissues because they have other, more significant functions or roles. They include:

• Digestive tract (stomach and small intestine): Your digestive tract is the largest endocrine-related organ system. It makes and releases several hormones that play a role in your metabolism. Examples include gastrin and ghrelin.
• Kidneys: Your kidneys are two bean-shaped organs that filter your blood. They’re part of your urinary system, but they also produce hormones, like erythropoietin and renin.
• Liver: Your liver is part of your digestive system, but it also produces hormones, including insulin-like growth factor 1 (IGF-1) and angiotensinogen.
• Heart: When your blood pressure rises, your heart releases two hormones called A-type natriuretic peptide and B-type natriuretic peptide.
• Placenta: The placenta is a temporary endocrine organ that forms during pregnancy. It produces hormones that are important for maintaining a healthy pregnancy and preparing your body for labor and breastfeeding (chestfeeding).

What are endocrine system diseases?

There are hundreds of conditions related to issues with your endocrine system. Hormonal imbalances make up a significant number of endocrine diseases. This typically means there’s too much or not enough of one or more hormones. But issues directly affecting endocrine system glands and organs, like benign and cancerous tumors, also account for endocrine diseases.

The below groupings cover some — but certainly not all — endocrine system-related conditions.

Diabetes and metabolic conditions:

• Type 1 diabetes.
• Type 2 diabetes.
• Gestational diabetes
• Metabolic syndrome.
• Obesity.

Endocrine cancers and tumors:

• Adrenal tumors.
• Neuroendocrine tumors.
• Pancreatic cancer.
• Parathyroid cancer.
• Parathyroid tumors.
• Pituitary tumors.
• Thyroid cancer.

Thyroid disease:

• Hypothyroidism and hyperthyroidism.
• Thyroiditis.
• Thyroid nodule.

Sexual development, function and reproduction conditions:

• Amenorrhea (absent periods).
• Erectile dysfunction.
• Growth hormone deficiency and excess (acromegaly or gigantism).
• Hormonal acne.
• Hormone-related infertility.
• Hypogonadism.
• Menopausal disorders.
• Polycystic ovary syndrome (PCOS).
• Premenstrual syndrome (PMS).

Calcium and bone conditions:

• Hypercalcemia and hypocalcemia.
• Osteopenia and osteoporosis.
• Vitamin D deficiency.

What healthcare providers treat endocrine system issues?

An endocrinologist is a healthcare provider who specializes in the endocrine system and conditions related to your hormones. They can diagnose endocrine conditions, develop treatment and management plans, and prescribe medication. Pediatric endocrinologists specialize in conditions that affect children under 18.

Some endocrine conditions may require more than one provider. For example, care for cancer affecting endocrine tissues would also involve oncologists and other cancer specialists.

How can I keep my endocrine system healthy?

It’s not possible to prevent all types of endocrine system-related conditions, like those that have autoimmune causes. But there are some steps you can take to try and keep your endocrine system healthy, including:

• Maintaining a weight that’s healthy for you.
• Exercising regularly.
• Getting proper nutrition.
• Getting quality sleep.
• Limiting or avoiding alcohol.
• Avoiding or quitting smoking.

Chemicals called endocrine disrupters can also affect your endocrine system. These chemicals are in many everyday products, including some:

• Cosmetics.
• Food and beverage packaging.
• Toys.
• Carpets.
• Pesticides.

You can’t completely avoid contact with endocrine-disrupting chemicals (EDCs). But you can make informed choices to reduce your exposure to them and your risk of any potential health effects.

Lastly, if you have a family history of endocrine system-related conditions, like diabetes or thyroid disease, talk to your healthcare provider. They can help you understand your risk of developing the condition and let you know what symptoms to look out for. 

A note from Cleveland Clinic

Your endocrine system is vital to your existence. While normally, your body carefully balances its hormones, having too little or too much of a certain hormone can lead to health problems. If you’re experiencing any concerning symptoms, it’s important to talk to your healthcare provider. They’re available to help.