The colon, or large intestine, is a muscular tube responsible for the final stages of digestion. Beginning where the small intestine ends, its primary function is to absorb remaining water and electrolytes from indigestible food matter. This reabsorption transforms liquid waste into a solid form, which the organ then stores and expels from the body.
The Average Mass of the Colon
The baseline weight of the colon refers only to the organ’s tissue, completely empty of contents, as measured in anatomical studies. The entire empty large intestine, including the colon, cecum, and rectum, weighs approximately 360 to 370 grams (12.7 to 13.1 ounces), or just under one pound. This figure represents the static mass of the muscular wall and mucosal lining. This measurement provides a static reference point for the organ’s physical structure. Since the colon is the longest segment, it contributes the most mass to this total figure.
Factors That Alter Colon Weight
The weight of the colon in a living individual is highly variable because the organ is rarely truly empty. The biggest contributor to this temporary mass is fecal matter, or stool, which continuously moves through the tract. Healthy adults typically carry a transient weight of colonic contents between 0.5 to 1.6 pounds (230 to 730 grams) at any given time.
Microbiota and Water Content
The gut microbiota, the community of microorganisms living in the colon, adds a relatively stable amount of mass. This bacterial biomass can weigh around 200 grams (0.44 pounds) and helps ferment undigested materials. Additionally, the large intestine contains approximately 187 grams of water, which is absorbed or retained based on the body’s hydration status.
Pathological Increases
Pathological conditions can dramatically increase the colon’s mass beyond normal fluctuations. Conditions like toxic megacolon involve extreme dilation and inflammation, causing the muscular wall to hypertrophy (thicken). This increase in tissue mass, coupled with a buildup of hardened fecal matter known as fecalomas, can lead to substantial weight gain within the abdomen.
Understanding the Colon’s Dimensions
While its weight is relatively low, the adult large intestine measures about 1.5 meters (5 feet) in length. This structure is positioned around the perimeter of the abdominal cavity, framing the smaller, much longer small intestine.
The diameter of the colon is not uniform throughout its length. The cecum, the pouch-like beginning of the large intestine, is the widest segment, averaging slightly less than 9 centimeters across. The transverse colon typically measures less than 6 centimeters in diameter, while the descending and sigmoid sections are slightly narrower.