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.
Lymph nodes are part of the immune system. They release lymphocytes, a certain type of white blood cell that fights infection. The blood vessels and lymph vessels carry the lymphocytes to and from different areas in the body. Each lymphoid organ plays a role in the production and activation of lymphocytes. Organs in the lymph system include: Adenoids.