So this is basically a structure that consists of three different types of cells. Now, two of these different types of cells are the maculadens of cells and the juxtaplamelmerolar cells. And these two different types of cells basically have their own unique function. So, basically, when our blood volume drops inside our vessels, when our blood pressure drops, and when the profusion rate inside our kidneys drops that simply means when the rate at which our fluid is passing through the kidneys drops, this causes our maculodenta cells to basically release a prostaglandin that travels to our juxtaglomero cells. And this causes those cells to release an enzyme called rena. Now, note that juxtaplinaril cells don't have to be activated, they don't have to be stimulated by the macula density to actually release Rena.