Endocrinology is defined as the study of the glands and the hormones of the body and their related disorders. Glands of the body include, the pituitary, located in the brain; the thyroid, located in the neck; the thymus, located in the chest region; the adrenals, which sit on top of the kidneys; the pancreas, located just below and behind the stomach; the ovaries in women, and the testicles in men. Hormones are the substances the the endocrine glands secrete directly in to the bloodstream. Some examples of the many different hormones found in the body are testosterone, estrogen, and insulin.