The pineal (pronounced: pih-NEE-ul) body, also called the pineal gland, is located in the middle of the brain. It secretes melatonin(pronounced: meh-luh-TOE-nin), a hormone that may help regulate when you sleep at night and when you wake in the morning.
The gonads are the main source of sex hormones. Most people don't realize it, but both guys and girls have gonads.
In guys the male gonads, or testes (pronounced: TES-teez), are located in the scrotum. They secrete hormones called androgens(pronounced: AN-druh-junz), the most important of which istestosterone (pronounced: tess-TOSS-tuh-rone). These hormones tell a guy'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 guy's body when it's time to produce sperm in the testes.
A girl's gonads, the ovaries (pronounced: OH-vuh-reez), are located in her pelvis. They produce eggs and secrete the female hormones estrogen (pronounced: ESS-truh-jen) andprogesterone (pronounced: pro-JESS-tuh-rone). Estrogen is involved when a girl begins to go through puberty. During puberty, a girl will experience breast growth, will begin to accumulate body fat around the hips and thighs, and will 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.
Although the endocrine glands are the body's main hormone producers, some other organs not in the endocrine system — such as the brain, heart, lungs, kidneys, liver, and skin — also produce and release hormones.
The pancreas (pronounced: PAN-kree-us) is also part of the body's hormone-secreting system, even though it is also associated with the digestive system because it produces and secretes digestive enzymes.
The pancreas produces (in addition to others) two important hormones, insulin (pronounced: IN-suh-lin) and glucagon(pronounced: GLOO-kuh-gawn). They work together to maintain a steady level of glucose, or sugar, in the blood and to keep the body supplied with fuel to produce and maintain stores of energy.