You might already know that we pass about two litres of gas a day, most of which escapes our body without us even noticing.
But how come our bodies know how to stop when the air does? After all, flatulence leaves via the same exit as faeces.
So if our bowels are full, and the door is open, then... what’s stopping us from accidentally letting it all loose?
Well, there’s good news an bad news: in a recent TikTok, GI surgeon Dr Karan Rajan said that our bodies are surprisingly good at telling a number two from a wandering whiff.
But HOW we tell the two apart is a little grosser than I, at least, expected.
How do our rectums tell farts from poop?
The doctor says our rectums sort of “sample” the substance in the rectal chamber before deciding what to do with it (hey, I’m just the messenger).
In his video, Dr Rajan explained that the “anal sampling mechanism,” also known as the “rectoanal inhibitory reflex”, is to thank for our clean undies.
“It’s a reflex that allows your body to sample the contents of the rectal chamber and allows the rectum to distinguish between a solid, liquid, and a gas,” he revealed.
The International Continence Society says it’s thought that the substances are “sensed by the anal mucosa” (tissue similar to the inside of our nose) in this mechanism.
Research says this “testing” may happen multiple times an hour. Oh, lovely.
Speaking to gut health company ZOE, gastroenterologist Dr. Will Bulsiewicz explained that once your body knows what it;s dealing with, it helps us to decide which of the two sphincters in our colon to open.
“We have two layers to the sphincter. The external is our squeeze muscle. Like when you decide to squeeze your cheeks to stop a poop from coming out, you are activating the external anal sphincter,” he shared.
The expert added that the recto-anal inhibitory reflex has to take place for the internal sphincter, which we have more control over and which holds our poop in, to release.
Can the process go wrong?
Even more “fun” news ― Dr Rajan says that though the system is “amazing,” it’s not perfect for most people.
It can struggle to tell the difference between solid and non-solids, and “sometimes it senses liquid as gas.”
The NHS says that some signs of faecal incontinence include:
- poo leaking out without you being able to stop it
- feeling like you need to poo, but not being able to get to the toilet in time
- not being able to get fully clean after going to the toilet
- seeing streaks or stains of poo in your underwear
If you notice any of these or have had changes to your stool that don’t go away, they recommend seeing your GP.