Question 1

Is your heart actually on the left side of your chest?

Accepted Answer

Not really. The heart sits near the center of the chest behind the breastbone, but it leans slightly left and its pointed lower tip, the apex, presses against the left ribs. That tip is the thump you feel.

Question 2

What decides whether your heart points left or right?

Accepted Answer

Tiny spinning hairs called cilia in a three-week-old embryo create a leftward flow of fluid. That flow activates genes on the left side, which guide the heart tube to loop and point its tip toward the left.

Question 3

What is situs inversus?

Accepted Answer

Situs inversus is a condition, affecting about one in ten thousand people, in which the internal organs are arranged as a mirror image of the usual layout. The heart points right and the liver sits left. When complete, people often live normally and never know.

embryology

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The Spinning Hair That Decided Which Way Your Heart Points