damage to the macula densa would impact blood flow to the kidneys because the afferent arterioles would not dilate in response to a decrease in filtrate osmolarity and pressure at the glomerulus would not be increased. as part of the body's blood pressure regulation, the macula densa monitors filtrate osmolarity; if it falls too far, the macula densa causes the afferent arterioles of the kidney to dilate, thus increasing the pressure at the glomerulus and increasing the glomerular filtration rate.