Luke Davis has illustrated the evolution of the 4-chambered heart In the 2-Chambered fish heart you can see there is only the need for the atrium and the ventricle because oxygen is absorbed through the gills. The 3-chambered heart with 2 atria and 1 ventricle is found in amphibians due to the oxygen being absorbed through the skin. The 3 chambered reptile heart only has 3 chambers because its metabolism is much slower which requires less oxygen per liter of blood to be delivered throughout the body. Finally, our 4 chambered heart consists of the left and right atrium and the lower chambers of the left and right ventricle. This ensures that we have complete segregation of oxygenated and deoxygenated blood. As the illustration shows, the 4 chambered heart found in mammals has only been around for about 170 million years.
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Luke Davis has illustrated the evolution of the 4-chambered heart In the 2-Chambered fish heart you can see there is only the need for the atrium and the ventricle because oxygen is absorbed through the gills. The 3-chambered heart with 2 atria and 1 ventricle is found in amphibians due to the oxygen being absorbed through the skin. The 3 chambered reptile heart only has 3 chambers because its metabolism is much slower which requires less oxygen per liter of blood to be delivered throughout the body. Finally, our 4 chambered heart consists of the left and right atrium and the lower chambers of the left and right ventricle. This ensures that we have complete segregation of oxygenated and deoxygenated blood. As the illustration shows, the 4 chambered heart found in mammals has only been around for about 170 million years.