Large Intestine

Digestion:

Digestion means a person's ability to digest food. Under this process food is treated with heat, enzymes, or a solvent to promote decomposition or to extract essential components from food. Under this process breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the bloodstream. During all these processing the digestive system/tract plays a very crucial role. The digestive tract is a long tube-like structure that starts with the mouth and ends in the large intestine. 


Large Intestine:

The large intestine is the last part of the gastrointestinal tract that performs the important task of absorbing water and vitamins while converting digested food into feces. Large intestine is shorter than the small intestine in length, the large intestine is considerably thicker in diameter. The length of the large intestine is about 1.5 m in length and 2.5 inches in diameter in the living body. The large intestine wraps around the border of the abdominal body cavity from the right side of the body, across the top of the abdomen, and finally down the left side.


Starting on the right side of the abdomen, the large intestine is connected to the ilium of the small intestine by ileocecal sphincter.


Picture of Large Intestine:

(image will be uploaded soon)


Large Intestine is Made up of Four Tissue Layer They are:

  1. The innermost layer of the large intestine is known as the mucosa and it is made up of simple epithelial tissue. Here mucosa lacks villi which is found in the small intestine. Many mucosal glands secretes mucus which helps in lubrication of food.

  2. Above the mucosal layer there is a layer of blood vessels, nerves and connective tissues known as submucosa, which provides support to other layers of the intestine.

  3. Further submucosal layer is surrounded by muscularis layer which contain several visceral muscle cells, which help in contraction and relaxation of the large intestine.

  4. Outermost layer of the large intestine is known as the serosa layer, they are made up of squamous epithelial tissue and their secretion helps in the lubrication process.


Parts of Large Intestine:

Large intestine is made up of three parts they are:

  1. Cecum: The cecum is the first part of the large intestine. The cecum is intraperitoneal with various folds and pockets commonly known as retrocecal peritoneal recess surrounding it. 

  2. Colon: Colon is further divided into two parts, they are:

  1. Ascending Colon:  It travels through the right iliac fossa, right flank, and right hypochondriac region . It ends at the right colic flexure. 

  2. Descending Colon: The descending colon extends between the left colic flexure and sigmoid colon. It travels through the left hypochondriac region, left flank and left iliac fossa.

  1. Rectum: The rectum stretches between the rectosigmoid junction and the anal canal.

  2. Anal Canal: The ana canal, forms the terminal part of the gastrointestinal tract. It extends from the anorectal junction to the anus. 


Function of Large Intestine:

There are so many major function of digestion which are performed by large intestine: 

  1. Formation and Elimination of Feces: When food is consumed by the small intestine then undigested food moves to the large intestine where absorption of remaining water takes place. Under this process conversion of liquid chyme into feces takes place. This feces consists of food, bacteria, inorganic salt, unabsorbed substance, etc.

  2. Absorption of Vitamins: Large intestine absorbs various vitamins produced by its own bacteria. There are more than 700 types of bacteria present in our large intestine. The major function of these bacteria are to breakdown left over fibre and polysaccharides and further convert them into short-chain fatty acid, which are absorbed by the large intestine by diffusion process.

  3. Absorption of Water and Electrolytes: During this process water is absorbed by the large intestine by osmosis process as during this process diffusion is happening as per concentration gradient. Sodium ion is absorbed by the sodium-potassium pump in the colon region.

  4. Antibody Production: The large intestine is a house for many lymphoid tissue, and these lymphoid tissue is crucial for immunity. They help in creation of various antibodies, which are helpful against various harmful bacteria.

  5. Acid Reduction: bicarbonates which are present in large intestine  neutralize acidity caused by the synthesis of fatty acids. 


Disorder of the Large Intestine:

There are several disorder which are caused in large intestine, they are:

  1. Constipation is one of the major disorders caused by any kind of  abnormality in the large intestine. During constipation there is painful and infrequent elimination of feces. This type of problem arises mainly due to dehydration.

  2. Coeliac disease is another disorder caused in the large intestine which leads to many problems like diarrhoea, abdominal pain, loss of appetite.

  3. Lactose intolerance is the most common type of disorder in the large intestine under this intestine is unable to digest lactose found in food and drink which cause gastric problems, bloating, cramps, etc.

FAQ (Frequently Asked Questions)

1. Define the Large Intestine?

The large intestine is the last part of the gastrointestinal tract that performs the important task of absorbing water and vitamins while converting digested food into feces.The length of the large intestine is about 1.5 m in length and 2.5 inches in diameter in the living body.

2. Different Parts of the Large Intestine?

Large intestine is divided into three parts they are:

  1. Caecum: The cecum is the first part of the large intestine. The cecum is intraperitoneal with various folds and pockets commonly known as retrocecal peritoneal recess surrounding it.

  2. Colon: Colon is further divided into two parts, they are:

  • Ascending Colon:  It travels through the right iliac fossa, right flank, and right hypochondriac region . It ends at the right colic flexure. 

  • Descending Colon: The descending colon extends between the left colic flexure and sigmoid colon. It travels through the left hypochondriac region, left flank and left iliac fossa.

  1. Rectum: The rectum stretches between the rectosigmoid junction and the anal canal.

3. Function of the Large Intestine in the Human Body?

There are several function which are performed by large intestine during digestion process:

  1. It helps in formation and elimination of feces.

  2. It absorbs various vitamins and minerals.

  3. It absorbs various electrolytes and water.