Believing that colon is the same as the large intestine may not be a bad conclusion given the fact that colon is the most prominent part of the large intestine. That is mainly because of the other parts of the large intestine being considerably small. Additionally, many information sources regarding this matter tend to explain as colon and large intestine being the same thing. However, this article intends to explain the difference between the two.
Colon
Colon is the largest and the most significant part of the large intestine of higher vertebrates. Colon is the main organ that is responsible for the absorption of water from the food. After the absorption of nutrients is completed at the small intestine, the remainder of the food is watery, which is subjected to go through the colon, and water with salts are absorbed into the body as the waste food passes. Colon is the main reason for the waste food in mammals being solid. Additionally, the functions of water and salt absorption are very important for animals to maintain the osmotic balance of the body. However, aquatic vertebrates such as fish do not have a significantly large colon, as they do not have to conserve water due to its availability in their habitat.
There are four major segments in colon known as Ascending colon, Transverse colon, Descending colon, and Sigmoid colon. The food is passed through the colon via peristaltic movements aided by smooth muscles called taeniae coli. Ascending colon is the first segment of colon, which connects anteriorly with the caecum and runs upwards. Therefore, the food is allowed to be fermented anaerobically with the aid of gut flora (bacteria species). The transverse colon is horizontal and encased in the peritoneum. The descending colon barely absorbs water and salt, as the food has become faeces by the time it reaches this segment of the alimentary tract. Therefore, the descending colon mainly stores the faeces before the elimination. Sigmoid colon is ‘S’ shaped and facilitated with muscles to provide pressure before releasing into the rectum for defecation.
Large Intestine
Large intestine is composed of caecum, colon, rectum, and anal tract. Starting from the ileocecal junction, the large intestine ends at the anus, which is collectively 1.5 metres long in humans. The human large intestine accounts for 20% of the total length of the alimentary tract. After food being entered to the large intestine, it lasts for about 16 hours until the elimination takes place as faces.
Colon is the most prominent part of the large intestine where water and salt absorption take place. Despite the fact that the main function is water recycling via absorption, storing of faeces temporarily and timely elimination are also managed by the large intestine. Cecum is the first part of the large intestine; water and salt absorption starts there and the contents are mixed with the mucus for lubrication and facilitation of gut flora for fermentation. As the contents have passed through the colon, the formation of faeces is completed. The rectum is the temporary storage of faeces, and it can stretch a little to expand the storage capacity. The stretch receptors in the rectal wall signal the nervous system to stimulate the defecation, but it could be temporarily kept inside the rectum, and the faeces returns to the colon. The sphincters in the anal canal can keep the alimentary tract closed tightly. However, if the defecation is not done for a considerable time, it could result in constipation or hardened faeces.
The large intestine, being the last part of the alimentary tract, performs very important functions such as recycling of water, salt, and some vitamins; in addition, the elimination of waste food and facilitation of fermentation through gut flora to further digest the materials are other important roles.
Colon vs Large Intestine
• Colon is a part of the large intestine.
• Colon has four segments while the large intestine has four major parts including the colon. Colon is the most prominent part, but caecum, rectum, and anal canal are also there in the large intestine.
• Colon is mainly responsible for water and salt absorption from the food, whereas large intestine performs a range of functions as a whole.
• Rectum of the large intestine has receptors of the nervous system to manage defecation, but colon does not have any nerve receptors that the animal directly feels.
• Anal sphincter is aided with skeletal muscles to control defecation, but colon has a rich supply of smooth muscles.