Ps: excuse me if I made any grammar mistake and please notice that I'm a simple med student from second year. I've got a lot ahead to learn and I may not be 100% right in this conclusion, but for me it's the most coherent reason. If someone knows completely the answer I'll be glad to hear it from them. Thanks.

It's actually the liberation of some hormones like adrenaline , that affect the heart, which is a muscle , and may cause some alterations in the heart rate or in its contractibility like I said before.

When we are affected by a feeling (bad or good) our nervous system sends this information to the heart and actives the parasympathetic or sympathetic system. These systems control your heart rate, that's why you get your heart to beat faster, for example, when you are in danger or nervous.
In our hearts there are some fine lines called chordae tendineae , that help the valves in your heart not to retract towards the auricules or the arteries when blood fills an atrium or a ventricle .
When we receive a very bad new we get this pain because it may happen the rupture or damage of the chordae tendineae, and some people actually get heart problems because of this.
Anyways, this doesn't mean that you have or will have a heart problem because once in a while you have felt this pain. This only occurs to a few people , so don't worry.

It gets better, I'm sure. Enjoy it!

Oh no! I never left. I'm just here quietly watching quietly all posts and enjoying them :) by the way did you change to international studies?

Quite good actually. At first I found it difficult to adapt to all the changes and stuff, and it took me a while (must say) but everything's fine now and I love studying this.
How is your sister? :)

So do I

(trust me, I'm a woman)

(already trying it)

But I'm sure she also thought it... :)

Don't forget your grandmother

I mean not the part when you want her to fall, but the other when you want to help her just to have an excuse