Facts About Rectums

Your colon plays a vital role in digestion. It’s an important part of your gastrointestinal (GI) tract, which makes up the digestive system.

By the time food reaches the colon, it’s already through most of the digestion process. The colon’s main role is to absorb water, vitamins, and electrolytes from partially digested food after it goes through the small intestine. Then, your colon prepares your body to get rid of the waste by passing stool (poop).1

Taking the mystery out of your colon will help you better identify signs of common colon problems and help you feel more comfortable talking about this hard-working body part with your healthcare provider.

The following facts will help re-acquaint you with your colon. You’ll learn where your colon is, how long your intestines are, the function of the large intestine, and even how much poop is in your body.


The Colon is 5 Feet Long

Male large intestine anatomy, illustration

Your colon, or large intestine, stretches from the end of your small intestine to your anus. In order, the parts of the large intestine are:2

  • Cecum
  • Ascending colon
  • Transverse colon
  • Descending colon
  • Sigmoid colon
  • Rectum
  • Anal canal

The large intestine is about five feet long and forms an inverted U-shape around your abdomen. Your colon is three inches wide at its widest point, the cecum. It’s just under an inch wide at its narrowest point, the sigmoid colon.2


Colon Transit Time Is 12 to 48 Hours

Wall clock
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Many people believe the food they eat comes out in their next bowel movement. It actually takes a long time for food to make its way through the entire length of your digestive system.

This length of time is known as transit time and can be measured with a colonic transit time test.

Average transit times vary depending on the person. Factors that affect transit time include:3

  • Race
  • Sex
  • Typical diet
  • Amount of physical activity

Transit time longer than 72 hours can be a sign of a bowel disorder.3


Bowel Movement Frequency Varies

man outside a public rest room
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Some people consider one bowel movement per day to be normal. But research doesn’t support this. The frequency of bowel movements varies widely among individuals and varies widely for any single individual.4


100 Trillion Microbes Live in Your Colon

illustration of various bacteria
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Our colons are host to trillions of microorganisms known as microbiota or gut flora. The majority of these organisms are bacteria.

The identification of the role of the microbiota led to the popularity of using probiotics as supplements and food additives to enhance digestive health and immune function.5


Your Colon Is Never Empty

row of glasses with various amounts of water
Larry Washburn/Getty Images

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.

Stool is made up of:

  • Bacteria
  • Liquid
  • Undigested food
  • Dietary fiber
  • Fat
  • Minerals
  • Protein

How Much Does Poop Weigh?

The weight of poop varies from person to person. However, adults generally excrete about 128 grams, or 0.25 pounds, of poop every day.6


Your Rectum Is Usually Empty

empty box on table
Richard Drury/Stone/Getty Images

The muscles that line the descending and the sigmoid colons move fecal matter into the rectum at periodic intervals. In response, the rectum expands and holds onto the stool.

Your internal and external sphincter muscles contain the stool within the rectum. Once you decide to have a bowel movement, voluntary and involuntary muscles work together to expel the stool.


The Colon Absorbs 1 Quart of Water a Day

Close-Up Of Glass Jar On Table At Restaurant
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It’s the colon’s job to complete the process of digestion. Its main purpose is to absorb water and electrolytes from the material passed from the small intestine. This material is then formed into a stool that can be passed during the process of a bowel movement.

When a person experiences diarrhea, they are passing stool that has not been in the colon long enough to have had enough liquid absorbed to firm up the stool.

The opposite occurs when a person experiences constipation. In that case, the stool has been in the colon too long and becomes dried out, hard, and difficult to pass.4


Meals Can Trigger a Bowel Movement

Dagwood sandwich, close-up
Tom Grill / Getty Images

One of your body’s reflexes is the gastrocolic reflex. When you eat something, this reflex kicks in and starts a process of movement throughout your entire digestive tract.

Large meals and fatty meals appear to cause a greater gastrocolic reflex and may prompt the need to poop.7 This information is useful for those who are prone to either constipation or diarrhea.

For the person with constipation, a large, fatty meal in the morning may work with the body’s natural biorhythms to encourage a bowel movement. The person prone to diarrhea should stick to small, low-fat meals.


Healthy Stools Are Not Always Brown

group of colorful stools
Leslee Mitchell/Moment/Getty Images

There’s no need to panic if you see some variation in the color of your stools. Various factors can affect stool color. Healthy stools typically fall into the brown range but can be yellow or orange as well.

Notify your healthcare provider if your stools are bright or dark red, or black or tar-colored. This may be a sign of internal bleeding.


You Can Live Without a Colon

Nothing beats the company of good friends!
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The nutrients from food that are essential for survival are mainly absorbed by your small intestine. Therefore, a person can have their colon removed and continue to have a healthy life.

Some health conditions, like colon cancer or inflammatory bowel disease, may make it necessary to remove a person’s colon. In some of these cases, a procedure called a colostomy is done. During the procedure, an opening is made in the abdomen so that fecal material can be collected outside of the body in a colostomy bag.

Another option is the use of a J-Pouch, in which the last part of the small intestine is used to hold stool internally.

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