There's a lot going on in our brains when we orgasm. People who have had orgasms inside fMRI scanners show just how which areas of the brain light up before and during the big O. While there's still a lot we don't know, we at least have a good idea what's going on.

1. Genital stimulation will send a signal to your limbic system. Go time.

The highly emotional area is activated when you're sexy-timing.

2. The brain responds to both orgasm and pain

Regions of the brain called the anterior cingulate cortex and the insular cortex increase in activity during sex. When they light up in response to pleasure, they can help inhibit pain sometimes. Which is why some people enjoy both. Sex. And pain. And that's why you have O-face too.

O face:

3. When you do orgasm...

It's like someone let out a huge firework. Your heart races. Pupils dilated. Sex flush. All thanks to the hypothalamus of the brain.

4. Then you release oxytocin, and dopamine.

The "bonding hormone" or the "cuddling hormone," and that's the reason why you feel loved after sex. It also releases dopamine, the happy hormone that rewards you for all the sex you just did.

Here's a video of what's going on: