The document summarizes the structure and function of the mammalian heart. It describes the four chambers of the heart - right and left atria and ventricles. It explains how blood flows through the heart, is pumped to the lungs or body, and is returned to the heart via veins. Valves ensure one-way blood flow. Mammals and birds have a four-chambered closed circulatory system where blood stays in vessels and nutrients diffuse between blood and tissues.

1. My heart is a muscle and it pumps blood Like a big old black steam train My veins are the tracks And the city is my brain - The Cruel Sea (1993)

2. The Heart

3. Animation

4. Right atrium Right ventricle Left atrium Left ventricle 1 2 3 4

6. Superior vena cava Inferior vena cava Left pulmonary artery Left pulmonary vein Right pulmonary vein Aorta 1 2 3 4 5 6 7 Right pulmonary artery

8. Tricuspid valve Pulmonary valve Mitral valve Aortic valve 1 2 3 4

16. right atrium lungs pulmonary arteries mitral valve right ventricle tricuspid valve pulmonary veins left atrium aortic valve vena cava pulmonary valve left ventricle aorta

17. BODY The Mammalian Heart