To maintain pressure in the glomerulus and therefore keep the glomerular filtration rate steady, angiotensin II constricts both the efferent and afferent arteriole, but with a much greater effect on the efferent arteriole. Remember, the effect of angiotensin II is greater on the efferent arteriole. This means that the blood entering the glomerulus has a much harder time leaving it because the exit is far smaller than the entrance. This causes a backup of blood in the glomerulus, increases the pressure within it and, therefore, keeps the GFR at an appropriate
