Cardiovascular so you can pump oxygenated blood through the heart
I'm pretty sure you can do it on both but a child would be safer to do cpr on to me because, on an infant their insides are still really fragile so you don't wanna press to hard :)
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I think lymph nodes produce white blood cells...so when you get sick, they produce many white blood cells to fight the bacteria or virus, and I assume they swell because they're over-producing white blood cells.
