Eicosanoids are often thought of as "local hormones". They have a variety of effects on in the body. Hormones are chemical messengers that regulate activities within the body. The thing about hormones is that they don't mind commuting. Many are produced in one area of the body, and then travel through the bloodstream to affect tissues located far away. Eicosanoids work like hormones, but they do not like to travel. Eicosanoids go by the nickname "local hormones" because they act on cells close to their site of production. Eicosanoids also rapidly break down, so they are not able to travel very far. There are different types of eicosanoids, but the three most researched types are prostaglandins, thromboxanes, and leukotrienes [Dr Rebecca Gillaspy] (see: Wikipedia).