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The large intestine is an important organ involved in the process of digestion. Digestion is the process of breaking down food materials into simple compounds which can be easily absorbed by blood and can be transported to the different parts of the body. The large intestine is a terminal segment of the gastrointestinal tract, which is a continuous, tube-like channel, through which the food passes along with the digestive system. The role of the large intestine is to absorb the water remaining in the indigestible food which compacts excrement prior to defecation.
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Key takeaways: Digestion, egested waste, large intestine, small intestine, feces, Parts of the large intestine, Disorders of large intestine.
What is a Large Intestine?
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The large intestine is an important organ in the digestive system. Its function is to absorb the water and vitamins present in the indigestible food and convert the digestible food into feces.
Fun fact: Large Intestine is smaller in length than the small intestine.
Large Intestine
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Size and location
The large intestine is considerably thicker than the small intestine. The large intestine extends up to 1.5 m in length and 2.5inches in diameter. The large intestine wraps around the corners of the abdominal cavity from the right-hand side of the body, across the top of the abdomen, and down to the left side.
Egested waste
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The rectum is the last part of the intestine that holds the waste. The indigestible food passes from the small intestine to the large intestine. All the water from undigested food is absorbed by the large intestine leaving the undigested food into semi-solid waste. This waste is stored for some time in the rectum and is eliminated from the body in the form of feces.
Histology of the Large Intestine
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There are four tissue layers in the large intestine -
- The innermost layer is known as mucosa and it is made up of simple epithelial tissues. Mucosal glands secrete mucus which helps in food lubrication.
- Just above the mucosal layer, there is a layer of blood vessels, nerve tissues and connective tissues known as submucosa which provides support to other layers.
- The submucosal layer is further covered by muscularis layer containing several visceral muscle cells, which help in the contraction and relaxation of the intestine.
- The outermost layer is known as the serosa layer which is made up of squamous epithelial tissues.
Parts of Large Intestine
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Large intestine is made up of three parts-
Cecum: The cecum is intraperitoneal with various folds and pockets and is commonly known as retrocecal peritoneal recess.
Colon: Colon has two parts -
- Ascending colon - It travels through the right iliac fossa, right flank, and right hypochondriac region.
- Descending colon - It extends between the left colic flexure and sigmoid colon. It travels through the left hypochondriac region, left flank, and left iliac fossa.
Rectum: The rectum stretches between the rectosigmoid junction and the anal canal.
Anal canal: The anal canal makes up the terminal part of the gastrointestinal tract. It extends from the anorectal junction of the anus.
Parts of Large Intestine
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Function of Large Intestine
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There are many functions of large intestine-
- Formation and elimination of feces: Water from undigested food is taken from the undigested food and the remaining food material is converted into a semi-solid substance called feces.
- Absorption of vitamins: Large intestine absorbs various vitamins produced by its own bacteria.
- Absorption of water and electrolytes: In this process, water is absorbed by the large intestine by the process called osmosis as diffusion is happening as per concentration gradient.
- Antibody production: The large intestine is the storehouse of many lymphoid tissues. These lymphoid tissues are very essential for immunity. They help in the creation of various antibodies which are helpful against harmful bacteria.
Disorders of the Large Intestine
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Some of the disorders which are caused in the large intestine is mentioned below -
- Constipation is one of the major disorders caused by any kind of problem in the large intestine. Dehydration is the main cause of constipation.
- Coeliac disease is another disorder that is caused in the large intestine which leads to problems like diarrhea, abdominal pain, and loss of appetite.
- Lactose intolerance is one of the most common types of disorder in the large intestine. In this disorder, the intestine is unable to digest lactose found in food and drink which causes gastric problems, cramps, bloating, etc.
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Things to Remember
- Digestion is the process of breaking down food materials into simple compounds which can be easily absorbed by blood and can be transported to the different parts of the body.
- The large intestine is a terminal segment of the gastrointestinal tract, which is a continuous, tube-like channel, through which the food passes along with the digestive system
- The large intestine’s function is to absorb the water and vitamins present in the indigestible food and convert the digestible food into feces.
- The rectum is the last part of the intestine that holds the waste.
- The large intestine extends up to 1.5 m in length and 2.5inches in diameter.
- Mucosal glands secrete mucus which helps in food lubrication.
Previous Year Questions
- Food is moved along the alimentary canal by the contraction known as... [JIPMER 2003]
- Which cells of "Crypts of Lieberkuhn" secrete antibacterial lysozyme?... [NEET 2017]
- Secretin and cholecystokinin are digestive hormones. They are secreted in….[NEET 2005]
- Which of the following statements is not correct?... [NEET 2015]
- Jaundice is a disorder of... [NEET 2010]
- A person who is eating boiled potato, his food contains the component...[NEET 2000]
- Anxiety and eating spicy food together in an otherwise normal human, may lead to...[NEET 2012]
- Calcium deficiency in the body occurs in the absence of...[NEET 1994]
- Duct leading from parotid gland and opening into vestibule is...[NEET 1998]
- Emulsification of fat is carried out by...[NEET 1990]
Sample Questions
Ques. Explain the process of digestion. (3 marks)
Ans. Digestion is the process of breaking down complex food materials into simpler compounds that can be easily absorbed into plasma and can be transported to different parts of the body. This process generates energy which is utilized by cells to carry out the different processes.
Ques. What is the location of the large intestine in the human body? (3 marks)
Ans. The large intestine extends up to 1.5 m in length and 2.5inches in diameter. The large intestine wraps around the corners of the abdominal cavity from the right-hand side of the body, across the top of the abdomen, and down to the left side.
Ques. Write in brief about the large intestine? (3 marks)
Ans. The large intestine is the last part of the gastrointestinal tract that performs important tasks like absorbing water and vitamins from the indigestible food. The large intestine is 1.5 m in length and 2.5 inches in diameter.
Ques. Mention any three functions of the large intestine in the human body? (3 marks)
Ans. There are many functions of the large intestine, some of them are -
- It helps in the formation and elimination of feces.
- It absorbs the water and vitamins from the indigestible food
- It absorbs minerals and electrolytes.
Ques. Mention some disorders caused in the large intestine. (3 marks)
Ans. Some of the disorders which are caused in the large intestine is mentioned below -
- Constipation is one of the major disorders caused by any kind of problem in the large intestine. Dehydration is the main cause of constipation.
- Coeliac disease is another disorder that is caused in the large intestine which leads to problems like diarrhea, abdominal pain, and loss of appetite.
- Lactose intolerance is one of the most common types of disorder in the large intestine. In this disorder, the intestine is unable to digest lactose found in food and drink which causes gastric problems, cramps, bloating, etc.
Ques. What do you mean by egestion? (3 marks)
Ans. The undigested and unabsorbed food is passed from the small intestine to the large intestine. All the water and minerals are absorbed by the large intestine and the remaining food is converted into a semi-solid substance called feces. These feces are later eliminated from the body through excretion. This process of elimination of food waste is called egestion.
Ques. What would happen if there is no large intestine in the body? (3 marks)
Ans. The large intestine can be removed from the body without affecting the digestion process. For some diseases like inflammatory bowel disease, the large intestine can be removed completely. Generally, it is replaced by a fecal pouch from the small intestine sutured to the anus.
Ques. Explain the different parts of the large intestine. (5 marks)
Ans. The large intestine consists of three parts -
Cecum: The cecum is intraperitoneal with various folds and pockets and is commonly known as retrocecal peritoneal recess.
Colon: Colon has two parts -
- Ascending colon - It travels through the right iliac fossa, right flank, and right hypochondriac region.
- Descending colon - It extends between the left colic flexure and sigmoid colon. It travels through the left hypochondriac region, left flank, and left iliac fossa.
Rectum: The rectum stretches between the rectosigmoid junction and the anal canal.
Anal canal: The anal canal makes up the terminal part of the gastrointestinal tract. It extends from the anorectal junction of the anus.
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