Three-dimensional visualization of the male and female endocrine system. The endocrine system is the regulator of the human body, responsible for maintaining homeostasis by producing and directing chemical messengers called hormones. Hormones act on nearly every cell to carry out a variety of functions related to metabolism, water and mineral balance, sexual development, growth, and stress reactions. Most hormones travel through the body via the bloodstream. Other hormones act locally and arrive at their site of action via microcirculation, the flow of blood through small vessels in the body.