A closed, double circulatory system
A closed, double circulatory system
The human circulatory system consists of the heart, blood vessels and blood. It is closed because blood remains inside vessels rather than flowing freely through the body cavity.
Step-by-step lessons on OCR GCSE Biology 2.2.3 The human circulatory system. Each one builds up to exam-style questions. Start with the foundational topics and build up to the higher-tier material.