For many of us, nothing quite gets us going in the morning like a cup of coffee. And when I say gets us going, I mean both mentally and physically, because it's no secret that for a lot of the population, coffee has an incredibly rapid laxative effect. So how exactly does a cup of coffee make you need to poop? In the latest episode of Reactions, a video series produced by the American Chemical Society, all is explained. And you'll never enjoy your morning espresso in quite the same way again.

But first off, we should explain that the coffee/poop question has both a long and a short answer. As the American Chemical Society explains in the video above, although scientists have long known that many people experience a laxative effect from coffee, and now understand the mechanism that triggers this, what's less clear is why this happens.

Initially, researchers thought caffeine was to blame for all the bowel movements. But then they discovered that decaffeinated coffee has the same effect, while energy drinks and caffeinated soft drinks don't, so they figured there had to be something else going on.

They now believe that one of these triggers could be the acidic nature of coffee, which causes our stomachs to secrete more gastric acid than usual. This boost in acidity can cause our stomachs to dump their contents more quickly into our intestines, which could help explain why coffee seems to speed the digestive process up so much.

But coffee also has an impact on our large intestine itself. The drink has been shown to increase levels of two hormones in our bloodstream called gastrin and cholecystokinin, which help us clear waste from our bodies. Gastrin is in charge of peristalsis, which is the wave-like relaxation and contraction of muscles that pushes waste out, and cholecystokinin triggers the release of digestive enzymes and bile that regulate the pooping process.

But this is where scientists get a little fuzzy, because even though they understand this mechanism, they're still not sure which of the nearly 1,000 compounds inside coffee is causing this effect.

Watch the video above to find out more about why coffee sends you running to the bathroom. And you know what's really cool? If you're reading this because you want to know why coffee goes right through you, then you're in an elite group, because the beverage only has a laxative effect on around 3 out of 10 people according to the American Chemical Society. Aw guys… we're special!