Circulatory System

A series of free Science Lessons for 7th Grade and 8th Grade, KS3 and Checkpoint Science in preparation for GCSE and IGCSE Science.

Circulatory System
The circulatory system consists of the heart and blood vessels (arteries, capillaries and veins). Arteries carry blood away from the heart towards an organ, while veins carry blood from an organ towards the heart.
The human circulatory system is a double circulatory system. It has two separate circuits and blood passes through the heart twice. The pulmonary circuit is between the heart and lungs and the systemic circuit is between the heart and the other organs.

What is in the blood?
Blood transports materials and heat around the body, and helps to protect against disease. It contains plasma, red blood cells, white blood cells and platelets.

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