The heart drives a double circulation
The heart drives a double circulation

The heart is a muscular organ that works as two pumps side by side. In a double circulatory system, blood passes through the heart twice during one complete circuit of the body.
Step-by-step lessons on AQA GCSE Biology 2.2.2 The heart and blood vessels. Each one builds up to exam-style questions. Start with the foundational topics and build up to the higher-tier material.