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.
The mature lymphocytes from primary lymphoid organs migrate to secondary lymphoid regions through blood circulation to give protection from invading foreign agents. The secondary lymphoid organs are the regions, where the immune competent lymphocytes interact with foreign agents and execute immune response. Production of antibodies from activated B cells, activation of cytotoxic T cells in response to antigens takes place in the secondary lymphoid organs.