Sexually transmitted diseases (STDs) are infections that are passed from one person to another through sexual contact. The causes of STDs are bacteria, parasites, yeast, and viruses. There are more than 20 types of STDs, including. Chlamydia. Genital herpes. Gonorrhea.
Society for Endocrinology. Hormones. Oxytocin is a hormone that acts on organs in the body (including the breast and uterus) and as a chemical messenger in the brain controlling key aspects of the reproductive system including childbirth and lactation, and aspects of human behaviour.
Target cells are specific to the hormone; a hormone specific to a target cell can only affect that target tissue because of the presence of receptors for the hormone on the target cells. Some endocrine glands are so complex and so specific that certain sections of the gland produce different hormones.