Why do our hearts have four chambers?

Dr. Michael Roizen, MD
Internal Medicine
As the heart develops in the unborn child, it takes on several distinct appearances, each resembling other animal hearts and each a step higher on the evolutionary ladder. At first, the tube-like heart is much like a fish heart. When it divides into two chambers, it is similar to a frog heart; with three chambers, a snake or turtle heart. Finally, with four chambers, the fully formed heart looks like what it is: the heart of a human being, the most highly evolved mammal.

The four-chambered heart has a distinct advantage over simpler structures: It allows us to send our "dirty" blood to the cleaners-the lungs-and our "clean" blood to the rest of the body without having to mix the two. That system is very efficient. The blood coming from the left side of the heart is pure, fully oxygenated, and ready to fuel the muscles. A fish heart, on the other hand, has to pump blood, which is only half as pure, to the body because it doesn't have separate chambers that enable it to clean the blood in one cycle and distribute it in the next.

Our sophisticated ticker allows us to process energy more efficiently and, therefore, move further from our energy source. We can do lots of work in between looking for food, while a fish has to live in its energy source, eating all the time.
YOU: The Owner's Manual, Updated and Expanded Edition: An Insider's Guide to the Body that Will Make You Healthier and Younger

More About this Book

YOU: The Owner's Manual, Updated and Expanded Edition: An Insider's Guide to the Body that Will Make You Healthier and Younger

Between your full-length mirror and high-school biology class, you probably think you know a lot about the human body. While it's true that we live in an age when we're as obsessed with our bodies as...

Continue Learning about Heart and Circulatory System

Heart and Circulatory System

Heart and Circulatory System

Your circulatory system is made up of your heart and three main types of blood vessels -- arteries, veins and capillaries. Your heart is at the center of the system, acting as a pump to distribute nutrient- and oxygen-rich blood t...

hrough your body; it then takes away carbon dioxide and other waste your body doesn't need. Signs of poor circulation include cold hands and feet, numbness, dizziness, migraines, varicose veins and pain in your feet or legs. Untreated, poor circulation can lead to stroke, high blood pressure, kidney damage and other diseases. Learn more about your heart and circulatory system with expert advice from Sharecare.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.