When listening to a heartbeat it consists of two thumps. Is it contracting twice very quickly or is the second thump caused by something else?
In: Biology
Your heart consists of two parts–the atria and the ventricles. The ventricles are the part that does all the actual contraction to push blood to your lungs (on the right side) or to the rest of the body (on the left side. There’s entry valves, which open inwards and close when the pressure in the ventricles get high; and exit valves, which open outwards and close when the pressure in the ventricles gets low.
The first sound (called “lub” in medicine…yes, really) is the sound of the “entry” valves to the ventricles slapping shut as the main contraction happens. The second sound (“dub”) is the sound of the “exit” valves snapping shut as the muscle relaxes and the heart starts to fill.
[This](https://www.youtube.com/watch?v=A2YoGyNhAns) is a nice animation.
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