The Physics of the Heart

As we are learning about fluids in motion, I started to wonder about the mechanism behind the pumping of the heart. The heart is made up of two different chambers: the two atria at the top of the heart and the two ventricles at the bottom of the heart. The heart beats by the contraction and relaxation of the heart muscle. To pump blood to the rest of the body, the heart muscle contracts the ventricle chambers causing the area to decrease.

Bernoulli's Equation

Due to the equation of continuity, we know that if the area decreases, the final velocity must increase and, therefore, the blood rushes from the heart to the rest of the body. Additionally, as the area decreases the pressure increases as shown by Bernoulli’s equation. This would force the blood to rush to regions of lower pressure, as fluids in motion flow from high pressure to lower pressure.

Finally, when the heart muscle relaxes, it increases the area of the atria chambers and, therefore, decreases the pressure, and the blood flows back to the heart to be re-oxygenated and cycled back out throughout the body again.