Cardiology

The heart pumps blood, very quickly.
In fact, it also does many other things.
It kills you from the inside,
It bursts, and it swells,
And can tear you apart.
It can make you say the most ridiculous things,
Like 'I love you'
And 'I hate you'.
It brings people together,
While it drives others to madness.
It's just like any other pump, really,
Except mine's just crazy about you.