What Is the Circulatory System 4 Your Heart 6 Your Blood 8 Your Blood Vessels 16 A Healthy Circulatory System 18 Glossary 22 To Learn More 23 Index 24
4 Can you feel your heart pound after a fast run Your heart works hard when you exercise It also works when you rest What Is the Circulatory System
heart blood vessels 5 The movements of your heart keep blood moving through your body Your heart pumps blood through tubes called blood vessels Your heart blood and blood vessels make up your circulatory system The Circulatory System
