Learn how blood flows through the heart, and understand the difference between systemic and pulmonary blood flow. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Ever wonder why the heart sounds the way that it does? Opening and closing of heart valves makes the heart rhythm come alive with its lub dub beats. Rishi is a pediatric infectious disease physician and works at Khan Academy. [9:50]

Learn the difference between the pulmonary and systemic circulatory systems in the body. Rishi is a pediatric infectious disease physician and works at Khan Academy.