Endocrinology is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormone, as well as the integration of developmental events proliferation, growth, and differentiation (including histogenesis and organogenesis), and also the psychological or behavioral activities of metabolism, growth and development, tissue function, sleep, digestion, respiration, excretion, mood, stress, lactation, movement, reproduction and sensory perception as caused by hormones. Significant diseases include: diabetes, thyroid disease, androgen excess.