Activated Platelet (IMAGE) University of Sydney Caption An activated human platelet -- a blood clotting cell that plays a crucial role in preventing bleeding or causing the cardiovascular diseases such as heart attack and stroke. Credit Lining Arnold Ju (University of Sydney) and Qian Su (University of Technology Sydney). 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.