Circulatory System
This picture shows the nerves, arteries, and spinal cord throughout an American Black Bear. The main abundance of nerves, arteries and veins in the center is where the heart is located. The heart of an Black Bear works the same way a human one does. It is true that all mammals have a 4-chambered heart, on the right side the blood comes in and goes to the lungs to be oxygenated. Once oxygenated the blood heads back into the left side of the heart where through the left atrium, left ventricle and aorta it is pumped to the rest of the body. The difference between a humans circulatory system and a Black Bear's is the path of the blood after the heart, instead of the blood going through mostly arteries to the rest of the body, American Black Bears have more veins than anything else. This is because veins have valves, which allow the blood from going the wrong way in the body. Where we stand on two legs so the blood has an easier time traveling down towards our libs where we need it, an American Black Bear is 4-legged so valves help the blood to only flow one way throughout the body.