The endocrine system helps regulate the body's functions through glands that release hormones directly into the bloodstream. Major glands include the pituitary gland, which controls other glands; the thyroid gland, which regulates metabolism; and the adrenal and gonadal glands, which regulate other processes like stress response and reproduction. Disorders can result from too much or too little hormone production and can affect growth, metabolism, and other bodily functions.