The endocrine system is made up of glands, that produce hormones, which tell your cells what to do.

The endocrine system is made up of many glands. Some are the pituitary, thyroid, parathyroid, adrenal and the pancreas.

The master gland; or the pituitary gland, is the gland of all glands. Although the pituitary gland is only the size of a pea, its one of the most important glands in the endocrine system.

The pituitary gland controls all of the other glands. So to simplify the pituitary gland tells the other glands what to do.

The parathyroid glands are four tiny glands located in the neck, that control calcium levels. They produce the parathyroid hormone, and regulate the amount of calcium in the blood, and the bones.

The parathyroid are located behind the thyroid, and are as small as a grain of rice.