Firstly, they can actually sense any fluctuation in sodium chloride concentration inside the lumen inside our distal convoluted tubule. And if the sodium chloride concentration inside the tubule drops, then what the maculus densa cells do is they are capable of stimulating the African arterial, this blood vessel right here, to actually dilate an increase in diameter. And that not only decreases the resistance of the blood flow, but it also increases the amount of blood that reaches arglomerilus and that increases the hydrostatic pressure in araglomerilus. And this controls or regulates the filtration rate inside our glomerulus, also known as the glomerul filtration rate. So function number one of macular density cells is to regulate the filtration rate within the nephron. Now the second function of macular density cells is to stimulate the release of certain types of molecules that go on to stimulate the other cells in the juxtaglomerelaparatus known as our granule cells.