Endocrinology is a branch of biology and medicine dealing with the endocrine system, diseases and specific secretions known as hormones. It is also related to the proliferation, growth and differentiation of developmental phenomena and psychological or behavioral activities related to metabolism, growth and development, tissue function, sleep, digestion, breathing, excretion, mood, stress, breastfeeding, movement, reproduction. Sensory perception caused by hormones. His areas of expertise include behavioral endocrinology and comparative endocrinology.