Closeup into a REAL blood clot. Blood clots within our vessels are what stop bleeding when we scrape our skin in a fall. But they are also the culprit behind both heart attacks and strokes, the two leading causes of death across the globe. In a heart attack or stroke, a blood clot can form over a ruptured atherosclerotic plaque, fully blocking arterial flow, causing death of the heart or brain tissue that was once fed by the previously open artery. We can prevent atherosclerosis and subsequent heart attacks and strokes with a diet low in saturated fat, healthy weight, exercise, and smoking cessation. Image: James Archer, electron microscope