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
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
, 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:
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
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
corticotropin (kor-tih-ko-TRO-pin), which stimulates the adrenal gland to make
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
The pituitary also secretes endorphins (en-DOR-fins), chemicals that act on the
nervous system and reduce feelings of pain. The pituitary also secretes hormones that
signal the reproductive organs to make sex hormones. The pituitary gland also controls
and the menstrual cycle in women.
Thyroid: The thyroid (THY-royd) is in the front part of the lower
neck. It's shaped like a bow tie or butterfly. It makes the thyroid hormones thyroxine
(thy-RAHK-sin) and triiodothyronine (try-eye-oh-doe-THY-ruh-neen). These hormones
control the rate at which cells burn fuels from food to make energy. The more thyroid
hormone there is in the bloodstream, the faster chemical reactions happen in the body.
Thyroid hormones are important because they help kids' and teens' bones grow and
develop, and they also play a role in the development of the brain and nervous system.
Parathyroids: Attached to the thyroid are four tiny glands that
work together called the parathyroids (par-uh-THY-roydz). They release parathyroid
hormone, which controls the level of calcium
in the blood with the help of calcitonin (kal-suh-TOE-nin), which the thyroid makes.
Adrenal Glands: These two triangular adrenal (uh-DREE-nul) glands
sit on top of each kidney. The adrenal glands have two parts, each of which makes
a set of hormones and has a different function:
The outer part is the adrenal cortex. It makes hormones called
corticosteroids (kor-tih-ko-STER-oydz) that help control salt and water balance in
the body, the body's response to stress, metabolism,
the immune system,
development and function.
The inner part is the adrenal medulla (muh-DUH-luh). It makes
catecholamines (kah-tuh-KO-luh-meenz), such as epinephrine (eh-puh-NEH-frun). Also
called adrenaline, epinephrine increases blood pressure and heart rate when the body
is under stress.
Pineal: The pineal (pih-NEE-ul) body, also called the pineal gland,
is in the middle of the brain. It secretes melatonin (meh-luh-TOE-nin), a hormone
that may help regulate when we sleep at night and wake in the morning.
Reproductive Glands: The gonads are the main source of sex hormones.
In boys the male
gonads, or testes (TES-teez), are in the scrotum. They secrete hormones called
androgens (AN-druh-junz), the most important of which is
(tess-TOSS-tuh-rone). These hormones tell a boy's body when it's time
to make the changes associated with puberty,
like penis and height growth, deepening voice, and growth in facial and pubic hair.
Working with hormones from the pituitary gland, testosterone also tells a boy's body
when it's time to make sperm in the testes.
gonads, the ovaries (OH-vuh-reez), are in her pelvis. They make eggs and secrete
the female hormones
(pro-JESS-tuh-rone). Estrogen is involved when a girl starts puberty.
During puberty, a girl will have breast growth, start to accumulate body fat around
the hips and thighs, and have a growth spurt. Estrogen and progesterone are also involved
in the regulation of a girl's menstrual
cycle. These hormones also play a role in pregnancy.
Pancreas: The pancreas (PAN-kree-us) makes insulin
(IN-suh-lin) and glucagon
(GLOO-kuh-gawn), which are hormones that control the level of glucose,
or sugar, in the blood. Insulin helps keep the body supplied with stores of energy.
The body uses this stored energy for exercise and activity, and it also helps organs
work as they should.
What Can Help Keep the Endocrine System Healthy?
To help keep your child's endocrine system healthy: