The Heart and Circulatory System

This lesson covers the structure of the heart, the double circulatory system and how the heart functions as a pump, as required by the Edexcel GCSE Combined Science specification (1SC0). You need to label the chambers, valves and major blood vessels, explain double circulation and understand cardiac output.

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The Double Circulatory System

Humans have a double circulatory system. This means blood passes through the heart twice on each complete circuit of the body:

1. Pulmonary circuit — Right side of the heart pumps deoxygenated blood to the lungs, where it picks up oxygen and releases carbon dioxide. Blood returns to the left side of the heart.
2. Systemic circuit — Left side of the heart pumps oxygenated blood to the body tissues, where oxygen is delivered and carbon dioxide is collected. Blood returns to the right side of the heart.