While the brain and nervous system provide instantaneous information messaging, thoughtful communication which occurs between the brain and the different tissues of the body within the endocrine system through hormones. Endocrinology is the study of hormones, including how they are secreted and the functions they perform.
Hormones are a vital part of our reproductive system. LH and FSH are two hormones that travel to the gonads. They stimulate the production of the human sex steroids known as testosterone and estradiol. Sex steroids communicate back to the pituitary gland. All of this communication is made possible by receptors.
Sex steroids can have a tremendous impact on individuals, affecting the ratio of muscle to fat in men and promoting balding and the growth of facial hair in women.