Endocrinology is a branch of medical science specialising in the study, disorders, diagnosis and treatment of the endocrine system (an integrated system of small organs) and their secretions, called hormones. The physicians who specialise in endocrinology are called Endocrinologists, who are trained in investigation, diagnosis and treatment for endocrine and hormonal disorders. Glands are located throughout the human body and release hormones into the bloodstream. Hormones can regulate different functions such as growth, mood and metabolism and are produced by endocrine glands such as the pituitary, thyroid and adrenal glands.