# Defecation & flatulence **URL:** \ **Category:** Factual Questions\ **Created:** [April 14, 2011, 9:08am UTC](https://boards.straightdope.com/t/defecation-flatulence/578348 "2011-04-14T09:08:14Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![scudsucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scudsucker/32/14101_2.png) [@scudsucker](https://boards.straightdope.com/u/scudsucker)\ **Post date:** [April 14, 2011, 9:08am UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/1 "2011-04-14T09:08:14Z")
Yesterday, as I was on a training run I realised I needed to defecate. It was fairly uncomfortable - using a phrase favoured by a friend, ‘the turtles head was poking out’ - but the public toilets on my route were locked. When I returned to my car, and started driving to my next appointment (where a toilet awaited) I started farting. Large farts, but without the sense of pressure that I experienced while running - in fact, releasing the farts allowed me a sense of comfort for the 20 minutes or so it took to drive to the destination. Along the way, I was struck by the observation that flatulence usually (in my case, at least) precedes the need to defecate - aside from the unfortunate phenomenon known colloquially as “sharting” wherein a fart is accompanied by a number 7 on the [Bristol Stool Scale](http://en.wikipedia.org/wiki/Bristol_Stool_Scale) So why does the gas precede the solid? I would expect the gas/solid to be fairly evenly spread throughout the colon, with peristalsis moving both at the same rate. Once I did get to the toilet, my deposit (a number 4 on the Bristol scale) was accompanied (as I would expect) a large amount of gas, fairly evenly spread throughout the experience. What then causes the initial gaseous build up? (I mean, the large reservoir of gas that precedes the main event - I know what actually creates the gas) As a bonus answer: aside form the aforementioned sharting, how come most people are able to discern and release a fart, without releasing a turd? The sense of pressure is the same, but somehow I know that I am doing a fart, when I am doing so, rather than soiling myself. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [April 14, 2011, 12:34pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/2 "2011-04-14T12:34:52Z")
Bacteria that break down foods (especially things like beans that require a fair am’t of effort from said bacteria) produce the gas, which is going to find it’s way out faster than waste matter that has to be dried out somewhat as it’s moved along through the colon. Not much is stopping the gas, as you can imagine. Now, If you are sort of stuck and you’ve plugged yourself up holding it in, there are still gases being produced, but they are corked off. Not really very complicated or mysterious. ---
**Author:** ![scudsucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scudsucker/32/14101_2.png) [@scudsucker](https://boards.straightdope.com/u/scudsucker)\ **Post date:** [April 14, 2011, 1:20pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/3 "2011-04-14T13:20:57Z")
If I am sort of stuck and I’ve plugged myself up holding it… why would the gas be able to move faster than the faeces? It should all be stuck in place. As there is no release for the gas, there is no reason why gas would migrate down towards the rectum - no pressure differential, if you will. I can get that once a fart is released, that creates a “low pressure” zone immediately in the area of the sphincter, and that gas would push its way past to equalise the pressure - hence the combination of flatulence and faeces when one does use the toilet. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [April 14, 2011, 1:57pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/4 "2011-04-14T13:57:54Z")
> [@scudsucker](#): > > there is no reason why gas would migrate down towards the rectum - no pressure differential, if you will. Sure there is. Regional peristaltsis (contractions of the smooth muscle of the bowel wall) sets up pressure differentials from one part of the bowel to the next. So the gas will move from areas of higher pressure to lower pressure, and it will do so easier and more quickly than the more dense liquid or solid matter. ---
**Author:** ![Dung\_Beetle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dung_beetle/32/7945_2.png) [@Dung\_Beetle](https://boards.straightdope.com/u/Dung_Beetle)\ **Post date:** [April 14, 2011, 3:15pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/5 "2011-04-14T15:15:23Z")
> [@scudsucker](#): > > What then causes the initial gaseous build up? (I mean, the large reservoir of gas that precedes the main event - I know what actually creates the gas) A fart is the lonely cry of an imprisoned turd. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [April 14, 2011, 3:27pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/6 "2011-04-14T15:27:06Z")
> [@Dung\_Beetle](#): > > A fart is the lonely cry of an imprisoned turd. Sheer poetry - and from someone with quite an appropriate username for the thread! ---
**Author:** ![Dung\_Beetle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dung_beetle/32/7945_2.png) [@Dung\_Beetle](https://boards.straightdope.com/u/Dung_Beetle)\ **Post date:** [April 14, 2011, 3:31pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/7 "2011-04-14T15:31:17Z")
Yeah, I just couldn’t stay away. As for the lonely cry thing, I read it somewhere…maybe even here! ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [April 14, 2011, 3:48pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/8 "2011-04-14T15:48:56Z")
> [@Dung\_Beetle](#): > > A fart is the lonely cry of an imprisoned turd. For a second there I thought I was reading Carson McCullers. ---
**Author:** ![nivlac](https://avatars.discourse-cdn.com/v4/letter/n/3bc359/32.png) [@nivlac](https://boards.straightdope.com/u/nivlac)\ **Post date:** [April 14, 2011, 5:54pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/9 "2011-04-14T17:54:46Z")
> [@scudsucker](#): > > If I am sort of stuck and I’ve plugged myself up holding it.. why would the gas be able to move faster than the faeces? It should all be stuck in place. … Also, wouldn’t it make sense that it takes a smaller orifice for the gas to escape vs. a turd? If you’re completely plugged up, nothing gets out, but let’s say there’s a slight crack 😉 in the plug? ---
**Author:** ![Wheelz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wheelz/32/5718_2.png) [@Wheelz](https://boards.straightdope.com/u/Wheelz)\ **Post date:** [April 14, 2011, 6:03pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/10 "2011-04-14T18:03:05Z")
I don’t have much to add, except that I’d never before heard of the Bristol Stool Scale, and now that I have, it’s certainly the first time I’ve ever seen fecal matter described as “Fluffy.” ---
**Author:** ![EvilTOJ](https://avatars.discourse-cdn.com/v4/letter/e/ee59a6/32.png) [@EvilTOJ](https://boards.straightdope.com/u/EvilTOJ)\ **Post date:** [April 14, 2011, 6:23pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/11 "2011-04-14T18:23:49Z")
I don’t know why I’m surprised there’s a real life scale out there for how soft your poop is. ---
**Author:** ![Noel\_Prosequi](https://avatars.discourse-cdn.com/v4/letter/n/b19c9b/32.png) [@Noel\_Prosequi](https://boards.straightdope.com/u/Noel_Prosequi)\ **Post date:** [April 14, 2011, 11:48pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/12 "2011-04-14T23:48:18Z")
Since you cited the “turtle’s head” expression, you probably are aware that there is a related expression - “turtle’s breath” - for the flatulence preceding the stool. The fact that someone has gone to the trouble of naming the phenomenon should give you some comfort that you are not alone in experiencing this. (You hint, with the phrase “in my case at least”, that you are not sure if the experience is common.) As to how you can tell the difference - I suspect it is because gas is more variable in the rectum than solids. One can feel the relatively rapid alteration/variability in the sense of distension caused by gas as opposed to solids. Our internal sense detectors are sufficiently sensitive to detect the difference. ---
**Author:** ![Wile\_E](https://avatars.discourse-cdn.com/v4/letter/w/c37758/32.png) [@Wile\_E](https://boards.straightdope.com/u/Wile_E)\ **Post date:** [April 15, 2011, 1:09am UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/13 "2011-04-15T01:09:19Z")
> [@Elendil\_s\_Heir](#): > > Sheer poetry - and from someone with quite an appropriate username for the thread! Dung Beetle is like the Poo Whisperer of the boards. ---
**Author:** ![Dung\_Beetle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dung_beetle/32/7945_2.png) [@Dung\_Beetle](https://boards.straightdope.com/u/Dung_Beetle)\ **Post date:** [April 15, 2011, 2:22am UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/14 "2011-04-15T02:22:46Z")
:o. Aw, shucks! ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [April 15, 2011, 4:16am UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/15 "2011-04-15T04:16:52Z")
What’s that smell…? ---
**Author:** ![rock\_party](https://avatars.discourse-cdn.com/v4/letter/r/e19b73/32.png) [@rock\_party](https://boards.straightdope.com/u/rock_party)\ **Post date:** [April 15, 2011, 5:05am UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/16 "2011-04-15T05:05:37Z")
Over in these parts we call it ‘prairie doggin’. ---
**Author:** ![Ostrya](https://avatars.discourse-cdn.com/v4/letter/o/35a633/32.png) [@Ostrya](https://boards.straightdope.com/u/Ostrya)\ **Post date:** [April 15, 2011, 8:41am UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/17 "2011-04-15T08:41:58Z")
~joins the **Dung Beetle** fan club~ 🙂 ---
**Author:** ![scudsucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scudsucker/32/14101_2.png) [@scudsucker](https://boards.straightdope.com/u/scudsucker)\ **Post date:** [April 15, 2011, 11:42am UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/18 "2011-04-15T11:42:10Z")
Thank you all kindly for your comments. I stand (or squat, maybe?) enlightened. ---
**Author:** ![Dung\_Beetle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dung_beetle/32/7945_2.png) [@Dung\_Beetle](https://boards.straightdope.com/u/Dung_Beetle)\ **Post date:** [April 15, 2011, 12:53pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/19 "2011-04-15T12:53:35Z")
> [@the lone cashew](#): > > ~joins the **Dung Beetle** fan club~ 🙂 You are too kind. I myself look to **lieu** for words of poo wisdom. Since reading his canoe story years ago, I’ve been waiting for a chance to use the word “pooberg” in conversation, but you’d be amazed how often the subject doesn’t come up. ---
**Author:** ![Wile\_E](https://avatars.discourse-cdn.com/v4/letter/w/c37758/32.png) [@Wile\_E](https://boards.straightdope.com/u/Wile_E)\ **Post date:** [April 15, 2011, 2:54pm UTC](https://boards.straightdope.com/t/defecation-flatulence/578348/20 "2011-04-15T14:54:58Z")
> [@Dung\_Beetle](#): > > You are too kind. I myself look to **lieu** for words of poo wisdom. Since reading his canoe story years ago, I’ve been waiting for a chance to use the word “pooberg” in conversation, but you’d be amazed how often the subject doesn’t come up. I always think of lieu as more of the fart guy but I think I missed this canoe story and must now seek it out. [Next page](https://boards.straightdope.com/t/defecation-flatulence/578348.md?page=2)