This book uniquely presents conceptual understanding as well as advancements in the field of endocrinology. It emphasizes the harmonization between the function and the structure of different endocrine glands in the body. The book s initial chapters introduce hormones  biological synthesis, structure, function, and signaling pathways. The subsequent chapters examine the functional relationship between hypothalamus and pituitary gland and its leading and regulating roles on other endocrine and non- endocrine organs.  A separate chapter discusses the synergistic functions of adrenal glands and pineal gland in the circadian rhythm and analyze the role of corticoids in carbohydrate and mineral metabolism.