In blood loss or dehydration, what does angiotensin II do at the glomerular arterioles?

1. Angiotensin II is a potent vasoconstrictor acting throughout the circulation. 2. At the glomerulus it constricts the afferent and the efferent arterioles alike. 3. Constricting both reduces the filtration rate and the renal blood flow together. 4. In blood loss or dehydration that is exactly what is wanted, since it limits further fluid loss. 5. Preserving blood volume and pressure is its primary role, and filtration is sacrificed to that end. 6. Constricting only the efferent vessel would raise filtration pressure and waste fluid the body cannot spare. 7. Dilating either vessel would increase renal flow at a moment when the body is trying to conserve volume. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 25 "The Urinary System", section 25.8 Endocrine Regulation of Kidney Function_