Understanding How The Bowel Works - Bladder & Bowel Community (2023)

The bowel is part of our digestive system and it works to digest the food we eat, absorb the goodness and nutrients into our blood stream, then process and expel the waste that the body cannot use.

The digestive system works by pushing food through the intestines which usually takes between 24 to 72 hours. Muscular contractions squeeze (peristalsis) the food through the different sections of the intestine. These different sections are separated by bands of muscles, or sphincters, which act as valves.

The passage of food from one area of the intestines to another is coordinated so that food stays in a specific area for long enough for the gut to do a particular job – absorb fluids and nutrients, or process and expel waste.

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Understanding How The Bowel Works - Bladder & Bowel Community (1)

The small bowel (small intestine)

Understanding How The Bowel Works - Bladder & Bowel Community (2)

The small bowel (or small intestine) is around 6 – 8 m long and roughly 2cm wide.

There are 3 parts of the small bowel (small intestine): the duodenum, the jejunum and the ileum.

Food passes from the stomach into the duodenum, which is the tube that leads from the stomach into the intestines. The food then passes through the jejunum and ileum before going to the large bowel (colon). The small bowel (small intestine) absorbs nutrients and much of the liquid from foods. At the point where food is passed from the small bowel into the large bowel (colon) it is of a ‘porridge like’ consistency.

The Large Bowel (Colon – large intestine)

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The large bowel (also known as the colon, or large intestine), starts at the final portion of the small bowel (small intestine) and goes all the way to the rectum. The large bowel (colon) is about 2m long and 6-7 cm wide.

This muscular tube is made up of the ascending colon, the transverse colon and the descending colon which ends at the rectum and the anus. The colon’s most important job is to store, process and get rid of waste. The colon also absorbs some nutrients and water. Key to this process are the hundreds maybe thousands of bacteria resident in the colon – both ‘good’ and ‘bad’ – which collectively make up the gut flora. The rectum can store waste but most of the time it’s empty. Waste is expelled through the anus.

The rectum and muscles

Once the bowel has done its work and absorbed nutrients from food, the waste travels to the rectum which stretches, triggering a message to the brain to say that the bowel is full and needs to be emptied. The pelvic floor muscles, when well-toned, ensure the anus remains closed until it’s time to go to the toilet.

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The rectum and anus

After food has travelled along the gut, it has become digested and the nutrients and fluids absorbed; the waste is then expelled through the rectum and anus.

The rectum and the upper portion of the anal canal are richly supplied with nerves. When the rectum is full, the nerves sense this fullness and then inform the brain whether this is due to gas or stool.

When we need to go to the toilet, the brain tells the anal sphincter muscles, via the nerves, to relax. As the muscles relax, the anus opens and the rectum empties. In some neurological and spinal conditions the brain cannot tell whether the bowel is full of waste (faeces) or just wind. This can lead to accidental leakage.

Anal sphincters

The anal canal is about 3 – 4cm long in women and sometimes slightly longer in men. The internal and external sphincters form 2 concentric rings which run along the length of the anal canal.

The internal anal sphincter (IAS) is made of smooth muscle and we do not have voluntary control of this muscle. It works automatically to keep the anus closed until we are ready to have a bowel movement.

The external anal sphincter (EAS) is made of striated muscle (the same as the pelvic floor muscles); we do have voluntary control over the EAS – allowing us to hold on if we are aware of wind or diarrhoea.

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The pelvic floor muscle

The pelvic floor muscles are layers of muscle stretched like a sheet from the pubic bone in the front, to the bottom of the backbone (coccyx). There are 3 openings through the pelvic floor in women and 2 in men -the anus (back passage), the vagina in women (birth canal) and the urethra (bladder outlet). The muscles support these 3 openings, but if they are weakened or not in good condition they cannot support the openings effectively.

An important part of the pelvic floor muscle regarding bowel control is the deepest layer called Levator Ani – which directly translated from Latin means ‘lift the anus’. One of the muscle groups within levator ani is the puborectalis. This muscle forms a supportive strap around the junction between the rectum and the anal canal and helps to keep us in control of our bowels by forming a flap like valve, which prevents stool passing too easily into the anal canal.

The sacral nerves

The brain tells the bowel what to do by sending electrical signals to the muscles in the pelvic floor, the sphincters and the urethra.

The commands from the brain to the bowel (colon) are sent as electrical impulses and are carried by a system of special fibres called nerves.

These signals start in the brain and go to the spinal cord and continue to the nerves located in the sacral area of the back.

Some of these sacral nerves go to the rectum, levator ani muscle, and external sphincter muscles, controlling their activities.

Two key sacral nerves that are vital to the functioning of the bowel are the pudendal nerve and the pelvic splanchnic nerve.

Through a series of reflexes and signals the nerves in the bowel is coordinated with the pelvic floor muscles and anal sphincters in order to store bowel contents until there is an appropriate place to go to the toilet and then to allow complete bowel emptying once on the toilet.

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This coordination ensures that the sphincters remain closed, opening only during defecation. So, when the rectum fills, and the pressure inside it increases, the nerves sense the pressure and tell the brain about it. The brain then sends signals via the nerves to keep the external sphincter closed. Normally, this prevents leakage and is called the guarding reflex.

When you need to go to the toilet, the brain tells the nerves to signal the rectum to empty, and relax the muscles surrounding the anus. The rectum empties and stool is expelled.

Sensory signals

The nerve pathways are also shared with fibres that carry sensory signals, such as pain or fullness. Pain that originates in the pelvic area is transmitted along these pathways to the sacral area, up the spinal cord and back to the brain.

The same happens as the rectum fills. This sensation of filling is registered by the nerves, which transmit the information to the brain.

The nerves can also tell the brain whether it’s gas or stool that’s filling the rectum.

For the bowel to function and work properly, and to relieve constipation, you need:

  • The nerves of the rectum and anus to be sending the correct messages to your brain, so that you can feel when stool or gas arrives in the rectum and can send messages to the muscles you want to hold on. These may not function normally in some neurological and spinal conditions and are sometimes damaged in childbirth.
  • The internal and external anal sphincters need to be working properly.
  • The stools should not be too soft or loose so that the sphincters can cope with holding on, but not so hard so that they are difficult to pass.
  • You need to be able to get to and onto a toilet and to be able to hold on until the correct place is reached.
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How does the bowel system work? ›

The bowel is part of our digestive system and it works to digest the food we eat, absorb the goodness and nutrients into our blood stream, then process and expel the waste that the body cannot use. The digestive system works by pushing food through the intestines which usually takes between 24 to 72 hours.

What is the pathway of poop? ›

Your stool passes out of your body through the rectum and anus. Another name for stool is feces. It is made of what is left after your digestive system (stomach, small intestine, and colon) absorbs nutrients and fluids from what you eat and drink.

Is the bladder connected to the bowel? ›

Both organs are positioned close to each other in the small pelvis facilitating interactions. Their striated closing and supporting muscles are part of the same pelvic floor structure. The distal colon and urinary bladder have a similar function of the storage and evacuation of faeces and urine, respectively.

Where is poop stored when constipated? ›

Fecal impaction is the result of severe constipation, when you're unable to regularly pass poop (stool or feces) and it backs up inside your large intestine (colon). Fecal impaction can also be defined by your inability to sense and respond to the presence of stool in your rectum.

How long does poop stay in your colon? ›

The bowel transit time varies, even in the same person. The average transit time through the colon in someone who is not constipated is 30 to 40 hours. Up to a maximum of 72 hours is still considered normal, although transit time in women may reach up to around 100 hours.

What organ controls bowels? ›

Several parts of the end of the gastrointestinal tract control bowel movements: the rectum and anal canal, the sphincters (circular muscles), and hemorrhoids. These are embedded in the pelvic floor muscles.

Where does all the poop and pee go to? ›

From the toilet, your poop flows through the city's sewage system along with all the water that drains from our sinks, showers and streets. From there, it goes to a wastewater treatment plant.

Where does poop go after flushing? ›

The big sewer pipes take all the sewage to a place where it is treated. This place is called a sewage treatment plant. All towns and cities have these. They are like a big factory where any harmful materials are removed.

What is poop called before its poop? ›

The rectum ampulla stores fecal waste (also called stool) before it is excreted. As the waste fills the rectum and expands the rectal walls, stretch receptors in the rectal walls stimulate the desire to defecate.

Which comes first bowel or bladder control? ›

Highly correlated to each other, first bowel control develops, then bladder control by day and finally bladder control at night. The relevance of these interrelations for toilet-training and for the management of enuretic and encopretic children is discussed.

Why do we pee after we poop? ›

When you do pass stool however, the relaxation of the stronger anal sphincter also decreases tension in the weaker urinary sphincter, allowing urine to pass at the same time.

Can your bowels block your bladder? ›

For example, when the bowel does not empty properly it will swell up and push down onto the bladder and could cause urinary problems. You can avoid constipation by following a healthy diet, which can also help some bladder problems.

What food will completely empty my bowels? ›

Apples and pears – Containing high levels of fibre, fructose and sorbitol, apples and pears are popular fruits that help you to empty your bowels. Also, apples and pears contain high levels of water content, which helps with digestion and with avoiding constipation. For best results, eat them raw.

How do I completely empty my bowels? ›

How to empty your bowels without straining
  1. Sit on the toilet properly: ...
  2. Brace – allow your stomach muscles to push forwards. ...
  3. With each urge to empty your bowels, repeat the brace.
  4. Keep your mouth slightly open and breathe out. ...
  5. As you finish, pull up your anorectal muscles (the muscles that control your bottom).

How to entirely empty your bowels every morning 1 minute routine? ›

10 ways to make yourself poop first thing in the morning
  1. Load up on foods with fibre. ...
  2. Or, take a fibre supplement. ...
  3. Drink some coffee — preferably *hot.* ...
  4. Get a little exercise in. ...
  5. Try massaging your perineum — no, really. ...
  6. Try an over-the-counter laxative. ...
  7. Or try a prescription laxative if things get really bad.
Jul 30, 2019

Why is my poop two feet long? ›

Extremely large poops may be the outcome of eating a very large meal or the result of chronic constipation that alters your bowel habits. If you've tried increasing your physical activity and upping fiber and water intake, and your poops still fill the toilet, it's time to talk to your doctor.

What food takes the longest to digest? ›

The foods with the longest time to digest are bacon, beef, lamb, whole milk hard cheese, and nuts. These foods take an average of about 4 hours for your body to digest. The digestion process still occurs even when asleep. Which means our digestive fluids and the acids in our stomach are active.

How many times a day should you poop? ›

You don't need to poop every day to be regular. It's normal and healthy to have a bowel movement anywhere between three times a week to three times a day. If you're producing soft, well-formed logs that aren't hard to push out, your bowels are probably in good shape.

What organ affects poop? ›

The large intestine includes the colon, rectum and anus. It's all one, long tube that continues from the small intestine as food nears the end of its journey through your digestive system. The large intestine turns food waste into stool and passes it from the body when you poop.

What is it called when you Cannot control your bowels? ›

Bowel incontinence, or faecal incontinence, is when you have problems controlling your bowels. It can be very upsetting and embarrassing, but it's important to get medical advice if you have it because treatment can help.

How do you fix a bowel control system? ›

Getting adequate fiber.

If constipation is causing fecal incontinence, your doctor may recommend eating fiber-rich foods. Fiber helps make stool soft and easier to control. If diarrhea is contributing to the problem, high-fiber foods also can add bulk to your stools and make them less watery.

Do planes empty their toilets in the air? ›

Airlines aren't allowed to drop sewage from the sky – pilots have no dump button – but there have been incidents. Fictional ones, too.

How do planes get rid of poop? ›

On a long-haul 747 flight, travelers might flush the toilets around 1,000 times, creating roughly 230 gallons of sewage—that's a lot of waste! When the aircraft lands, a “honey truck” siphons out the waste and disposes of it into the airport's underground sewage system.

What happens when you flush the toilet with the lid open? ›

Research published in 2013 by the University of Oklahoma and the Centers for Disease Control and Prevention have found that fecal matter, along with various pathogens and water particles, can blast through the air and on surfaces after flushing the toilet without the lid on.

How far does feces travel when you flush the toilet? ›

During the experiment, airborne particles ejected from the toilet traveled at speeds of up to 6.6 feet per second and reached 4.9 feet above the toilet within eight seconds, the scientists found. And, once airborne, smaller particles measuring less than 5 microns hung in the air for more than a minute.

How many gallons does it take to flush a poop? ›

Older Toilets Use More

Generally speaking, the older the toilet, the more water it uses. Toilets built before 1982 use 5 to 7 gallons per flush. Now, toilets are designed to flush using only 1.6 gallons of water.

What chemical dissolves human feces in toilet? ›

Some studies have concluded that the additives ash, urea, lime and lactic acid can sanitise faecal sludge safely [3, 9, 11, 12].

Should poop float or sink? ›

Healthy Poop Should Sink in the Toilet

Floating stools are often an indication of high fat content, which can be a sign of malabsorption, a condition in which you can't absorb enough fat and other nutrients from the food you're ingesting, reports Mount Sinai.

How long does it take to poop out food? ›

It takes about 36 hours for food to move through the entire colon. All in all, the whole process — from the time you swallow food to the time it leaves your body as feces — takes about two to five days, depending on the individual.

Why do I poop after every meal? ›

Passing stool immediately after a meal is usually the result of the gastrocolic reflex, which is a normal bodily reaction to food entering the stomach. Almost everyone will experience the effects of the gastrocolic reflex from time to time. However, its intensity can vary from person to person.

How long should you sit on the toilet? ›

Most professionals recommend spending no more time on the toilet than it takes to pass a stool. Studies have shown that the average bowel movement takes 12 seconds. Sometimes it does take longer, however, so at maximum, you should not spend more than 10 minutes on the toilet.

What part of the brain controls bladder and bowel? ›

Brainstem. The brainstem is located at the base of the skull. Within the brainstem is the pons, a specialized area that serves as a major relay center between the brain and the bladder (see the image below). The pons is responsible for coordinating the activities of the urinary sphincters and the bladder.

What does it mean when you feel like you have to pee right after you pee? ›

A urinary tract infection (UTI)

Besides frequent urination, signs of a UTI include fever, a burning feeling when you pee, discolored urine and constantly feeling like you need to pee (even after peeing). You may also feel bladder pressure or discomfort in your back or around your pelvis.

Is it possible to pee and poop at the same time? ›

The pelvic floor muscles relax when we defecate. However, they will not necessarily have to fully relax when we urinate. But when the pelvic floor musculature does relax, in addition to allowing stool to pass, it decreases the tension in our urinary sphincters, allowing urine to flow.

How do people without legs pee? ›

A small flexible tube (urinary catheter)) may be placed in your bladder during surgery to drain urine. This means you will not need to get out of bed to go to the toilet for the first few days after the operation. You may be given a commode or bedpan so you can also poo without having to get up to use the toilet.

Can men pee and poop at the same time? ›

The male body passes urine extremely close to the bowels and anus; in fact, when your rectum is ready to “send the kids off to the pool”, it presses up against your prostate and gives you the inability to pee and poo until the poo has passed. I can pee and poop at the same time.

Does a full bowel put pressure on the bladder? ›

Large amounts of stool in the colon can put pressure on the bladder which can cause the bladder to not fill as much as it should, or cause the bladder to contract when the bladder is not supposed to contract. This large amount of stool can also cause the bladder to not empty well.

What drug can cause loss of bowel or bladder control? ›

Antibiotics, such as cephalosporins (eg, cefaclor), penicillins (eg, amoxicillin), or macrolides (eg, clarithromycin) Cancer medications, such as cyclophosphamide, 5-fluorouracil, or paclitaxel. Laxatives, such as lactulose, docusate, or bisacodyl. Antacids that contain magnesium.

What drinks help you poop? ›

What to drink to make you poop? The following drinks can help relieve constipation: prune juice, lemon juice, apple juice, kefir, coffee, green tea, water or aloe vera juice.

What is the best food to keep your bowels regular? ›

Fibre rich foods include:
  • Wholegrains including breakfast cereals, whole wheat pasta and rice, wholegrain bread and oats.
  • Fruit such as berries, pears, melon and oranges.
  • Vegetables such as broccoli, carrots and sweetcorn.
  • Peas, beans and pulses such as lentils, kidney beans and butter beans.
Jan 2, 2020

What causes the bowels not to empty? ›

Causes of incomplete bowel movement

motility disorders of the intestines, including pelvic floor dyssynergia. prolapsed hemorrhoid. rectal abscess. infection of the colon.

What helps empty bowels every day? ›

If you aren't pooping as easily or often as you'd like, addressing these aspects can help.
  • Drink water. ...
  • Eat fruits, nuts, grains, and vegetables. ...
  • Add fiber foods slowly. ...
  • Cut out irritating foods. ...
  • Move more. ...
  • Change your bathroom posture. ...
  • Keep your bowel movements in mind.
Mar 20, 2019

What happens when you push too hard to poop? ›

Consistently straining when pooping can cause a number of health complications, including: Hemorrhoids. These swollen veins in your lower rectum and anus can cause pain, burning, and itching. To relieve the discomfort of hemorrhoids, try soaking in a warm bath for 10 minutes a day.

Is your colon ever empty? ›

Your Colon Is Never Empty

Many people believe they have emptied out their colons after multiple episodes of diarrhea or that they can keep their colons empty by avoiding food. However, since stool is made up in large part of bacteria, fecal matter is continuously being formed.

What causes incomplete evacuation of stool? ›

Causes of tenesmus include irritable bowel syndrome or ulcerative colitis. In some cases, you may actually have stool left behind (incomplete evacuation of stool). This happens when your anal and pelvic muscles do not coordinate well to allow stool to exit your body.

Does oatmeal make you constipated? ›

Oats are loaded with soluble fiber, which is a type of fiber that allows more water to remain in the stool,” says Smith. “This makes the stool softer and larger, and ultimately easier to pass.”

What exercises promote bowel movement? ›

If you are already fit, you might choose aerobic exercise: running, jogging, swimming, or swing dancing, for example. All of these exercises can help keep the digestive tract healthy. Stretching may also help ease constipation, and yoga may, too.

How many times a day should I poop? ›

You don't need to poop every day to be regular. It's normal and healthy to have a bowel movement anywhere between three times a week to three times a day. If you're producing soft, well-formed logs that aren't hard to push out, your bowels are probably in good shape.

How long does it take to digest food and poop it out? ›

The length of time it takes to complete the trip from mouth to anus is called the transit time. This time varies from person to person but is usually around 24 hours for someone with a fiber rich diet. There are many factors that determine how long it will take for food to pass through the body.

How do you keep your bowels healthy? ›

Make sure you drink enough water. Eat a healthy and varied diet.
Drink enough water
  1. Drink up to 8 glasses of fluid per day e.g. water, milk, soups and juices.
  2. Limit caffeine drinks to 2 per day.
  3. Eat food high in soluble fibre (pasta, rice, vegetables and fruit).
  4. Limit foods high in insoluble fibre (bran and muesli).

What are the signs of bowel problems? ›

Bowel disorders affect how your body digests and absorbs food. They can cause uncomfortable symptoms, such as diarrhea or constipation.
For example, you might experience:
  • discomfort or pain in your abdomen.
  • gas and abdominal bloating.
  • nausea.
  • diarrhea.
  • constipation.
  • vomiting.

What is the fastest food can pass through you? ›

The quickest to digest are processed, sugary junk foods like candy bars. Your body tears through them in a matter of hours, quickly leaving you hungry again.

How do you stimulate a sluggish bowel? ›

Eat high-fiber foods such as whole-wheat grains, fresh vegetables, and beans. Use products containing psyllium, such as Metamucil, to add bulk to the stools. Try to drink 2 to 3 liters of fluid a day (unless you have a medical condition that requires you to restrict your fluid intake).

What are the most common bowel problems? ›

Constipation, irritable bowel syndrome (IBS), nausea, food poisoning, gas, bloating, GERD and diarrhea are common examples. Many factors may upset your GI tract and its motility (ability to keep moving), including: Eating a diet low in fiber. Not getting enough exercise.

What are serious bowel conditions? ›

Types of bowel problems

Common issues such as constipation and difficulties emptying the bowel, faecal incontinence, bowel urgency and diarrhoea. Divertucular Disease. Irritable Bowel Syndrome. Inflammatory Bowel Disease (e.g. Crohn's and Ulcerative Colitis).

Can bowel problems affect the bladder? ›

Large amounts of stool in the colon can put pressure on the bladder which can cause the bladder to not fill as much as it should, or cause the bladder to contract when the bladder is not supposed to contract. This large amount of stool can also cause the bladder to not empty well.


1. Bowel, Bladder, and Pelvic Pain Program | Middlesex Hospital
(Middlesex Hospital)
2. Promoting Healthy Bladder and Bowel Habits in Schools
(Continence Foundation of Australia)
3. Standards of Practise: Bladder + Bowel Care
4. Managing Bladder and Bowel Issues in MS
5. Physical Therapy for Your Bladder and Bowel
(Can Do Multiple Sclerosis)
6. Good bladder and bowel habits—pelvic floor exercises | Gynaecology surgery | Mater Mothers
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