Day 2: The Heart of the Matter

Comparative Anatomy of the Chicken Heart

A Chicken's Heart A Human's Heart

Like the human heart, the chicken heart has four chambers - a right atrium and ventricle which receives deoxygenated blood from the body and sends it to the lungs and a left atrium and ventricle which receives oxygenated blood from the lungs and sends it to the body.

Birds have a much higher metabolic rate than humans. The average body temperature of a chicken is 41-45 degrees C, compared to a human's average body temperature of 37 degrees C. The pulse rate of a chicken can reach as high as 400 beats/min. All of these factors place a great demand on the chicken's heart which has to work much harder than a human heart.

The chicken's heart is adapted to handle the increased stress placed on it by its high metabolic rate. The size of the heart in relation to body mass is larger in birds (about 0.8%) than in mammals (about 0.6%). The inside walls of the atria and ventricles are much smoother than those of the human. And the valves, though present, are much simpler. The smoother walls and simpler valves of the bird's heart reduces friction as the blood is pumped through; less friction means less work.

The ventricles of the bird heart have more muscle mass and less chamber space than those of a human. Externally, the ventricles appear more slender and pointed than in a human heart.

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