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Endocrine System
Reviewed by: Larissa Hirsch, MD
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Sistema endocrino
What Is the Endocrine System?
The endocrine system is made up of glands that make hormones. Hormones are the body's chemical messengers. They carry information and instructions from one set of cells to another.
The endocrine (EN-duh-krin) system influences almost every cell, organ, and function of our bodies.
What Does the Endocrine System Do?
Endocrine glands release hormones into the bloodstream. This lets the hormones travel to cells in other parts of the body.
The endocrine hormones help control mood, growth and development, the way our organs work, metabolism , and reproduction.
The endocrine system regulates how much of each hormone is released. This can depend on levels of hormones already in the blood, or on levels of other substances in the blood, like calcium. Many things affect hormone levels, such as stress, infection, and changes in the balance of fluid and minerals in blood.
Too much or too little of any hormone can harm the body. Medicines can treat many of these problems.
What Are the Parts of the Endocrine System?
While many parts of the body make hormones, the major glands that make up the endocrine system are the:
hypothalamus
pituitary
thyroid
parathyroids
adrenals
pineal body
the ovaries
the testes
The pancreas is part of the endocrine system and the digestive system. That's because it secretes hormones into the bloodstream, and makes and secretes enzymes into the digestive tract.
Hypothalamus: The hypothalamus (hi-po-THAL-uh-mus) is in the lower central part of the brain. It links the endocrine system and nervous system. Nerve cells in the hypothalamus make chemicals that control the release of hormones secreted from the pituitary gland. The hypothalamus gathers information sensed by the brain (such as the surrounding temperature, light exposure, and feelings) and sends it to the pituitary. This information influences the hormones that the pituitary makes and releases.
Pituitary: The pituitary (puh-TOO-uh-ter-ee) gland is at the base of the brain, and is no bigger than a pea. Despite its small size, the pituitary is often called the "master gland." The hormones it makes control many other endocrine glands.
The pituitary gland makes many hormones, such as:
growth hormone, which stimulates the growth of bone and other body tissues and plays a role in the body's handling of nutrients and minerals
prolactin (pro-LAK-tin), which activates milk production in women who are breastfeeding
thyrotropin (thy-ruh-TRO-pin), which stimulates the thyroid gland to make thyroid hormones
corticotropin (kor-tih-ko-TRO-pin), which stimulates the adrenal gland to make certain hormones
antidiuretic (an-ty-dy-uh-REH-tik) hormone, which helps control body water balance through its effect on the kidneys
oxytocin (ahk-see-TOE-sin), which triggers the contractions of the uterus that happen during labor