Controlling Blood Flow to Tissues (IMAGE) University of California - San Diego Caption Arterioles constrict and relax in response to a variety of factors, including viscosity enhancers. Credit UC San Diego, Jacobs School of Engineering Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.