A hormone is a substance made by one tissue and carried by the bloodstream to another tissue in which it exerts some effect.
Sex hormones affect the growth and function of the reproductive organs.
They also impact sexual behavior. The development of secondary sex characteristics, such as breasts in women and a deeper voice in men, is controlled by these hormones, as well. The menstrual cycle, pregnancy, and lactation are directed by the female sex hormones. The hormone levels fluctuate and are closely interrelated. Disorders may be due to an excess or deficiency of hormone, or the target tissue may be unable to respond to the hormone.