The pituitary gland is a pea-sized organ at the base of your brain that controls many of your body's most important functions by releasing chemical messengers called hormones into your bloodstream. Despite being barely larger than a jellybean, it's sometimes called the “master gland” because it tells other glands throughout your body what to do.

Your pituitary gland manages an impressive range of jobs. It signals your bones and muscles when to grow during childhood and adolescence. It helps control how much you urinate and how thirsty you feel. It tells your thyroid gland (in your neck) to regulate your energy levels and metabolism. It even responds to stress by triggering the release of hormones that help your body handle emergencies.

The gland sits in a small, bony pocket behind the bridge of your nose, protected by your skull and connected to a part of your brain called the hypothalamus. The hypothalamus acts like a command center, sending signals to the pituitary about what the body needs, and the pituitary responds by releasing the right hormones at the right times. When doctors discover that someone isn't growing normally or has certain medical problems, they often check whether the pituitary gland is working properly, since so many body systems depend on its signals.