Let's discuss the three ways by which our cells can basically communicate with one another using chemicals, using molecules. Now we basically have an autocrine signaling pathway, we have a paracrine signaling pathway and we have the endocrine signaling pathway that is used by the endocrine system. Now an autocrine signaling basically means that our cell produces some type of chemical. That cell releases that chemical into the extracellular fluid and then that chemical binds onto that same cell that release that chemical and creates some type of change. And some examples of this will be seen in the immune system when we'll discuss the immune system of the human body. Now the second type of signaling pathway is our paracrine signaling pathway.