how to draw a mammalian heart

1. Draw a straight pencil line down the centre of the page 2. Now draw parallel lines on both sides of this first line, about one centimetre away from it. These lines should reach from the top of the first line to about two thirds of the way down it. 3. Next draw the side outlines for the right and the left. 4. Now give these walls some thickness. The atria walls are thin, the right ventricle wall is thicker than the atria walls. The wall of the left ventricle should be made thicker than the right. 5. Now add the valve flaps and the cords. 6. Make your diagram less angular by curving the ends of the arteries. You can also put the semi-lunar valves in position. Now label the different parts of the heart. Add arrows to show the direction of the blood flow. Use two different colours – one for blood rich in oxygen (oxygenated blood) and the other for blood low in oxygen (deoxygenated blood).