Why does gas cause pain?

Question

If I have gas in my intestines, why does it hurt?

The mayo clinic has a lot of words, that describe the how and why you get gas.

Anything that causes intestinal gas or is associated with constipation or diarrhea can lead to gas pains. These pains generally occur when gas builds up in your intestines, and you're not able to expel it. Most people pass gas at least 10 times a day.

There are a few answers at Methods for dealing with gas pains? talking about how to get rid of gas.

But why do some, health people feel pain when they have gas? I can't imagine the gas bubble has a sharp point, so it's not like the gas bubble is poking your intestine.

Pain is "An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage." so some mechanism must be turning the physical presence of gas in the intestine to pain. What is that mechanism?

Clarify: this question is about a healthy persons normal daily gas causing occasional pain.

Answer 1

Try this: poke your tongue out of your mouth and, holding your hand in front of your mouth, jab your hand (finger, palm, whatever) a little with your tongue. Push at your hand. I predict your hand will interpret this as a very soft contact and nothing the slightest bit painful. Go ahead and push as hard as you can.

Next, push your tongue against your cheek so that your cheek bulges out a little and stretches. Push harder. Keep going. It hurts, right? In fact, you probably have to stop before you push as hard as you did against your hand. Your tongue isn't sharp, but the pain probably feels sharp.

Stretching is a different form of pain than other pressure sensations. I don't know why, but it is. The gas bubble distending the intestine locally is like your tongue distending your cheek. Someone even did a study (excerpt) putting balloons into people to prove that it is the distension in the intestine that is causing the reported pain.