Flight 3606 turned back over Idaho and flew back to Seattle-Tacoma International Airport to return the heart, which should have been taken off a previous flight on December 9.

It's tipped slightly so that a part of it sticks out and taps against the left side of the chest, ... During an average lifetime, the human heart will beat more than 2.5 billion times.

Before we get into the nitty gritty, let’s have a little GCSE Science refresher. The human heart is home to four chambers: the left and right atria make up the upper chamber, and the left and ...

Heart chambers. On the inside, the heart is a four-chambered, hollow organ. It is divided into the left and right side by a wall called the septum.