how does blood pressure affect glomerular filtration?
 Constriction of the afferent arteriole decreases the blood flow into the glomerulus and thus the glomerular hydrostatic pressure, which leads to a decrease in GFR. In contrast, constriction of the efferent arteriole decreases blood flow out of the glomerulus, and this increases the glomerular hydrostatic pressure and leads to an increase in glomerular filtration rate. 