Large Intestine
Large Intestine

Large Intestine: 4 Anatomy, Histology, Structure, and Function

The large intestine or colon in the anatomy is the intestinal part between the appendicitis and the rectum. The main function of this organ is absorbing water from feces. In mammals, the colon is made up of ascending, transverse, colon (descending), sigmoid colon, and rectum.

The colon from the appendectomy to the mid-transverse half is often referred to as “right colon”, while the remaining is often referred to as the “left colon”.

Anatomy and Histology of Large Intestine

Macroscopic colon can be divided into six parts, i.e. Cecum, ascending colon, transverse colon, the Descending colon, sigmoid, and rectum.

These six sections are difficult to distinguish histologically. The main characteristic of the cecum, the colon, and the rectum is that it does not form a small intestine-like villi, having a long and simple tubuli-shaped gland, does not have an acidophilic granular cell (Panneth cells), and has a lot of lymphatic nodules.

Cecum

This large intestine section is shaped like a pouch that connects the ileum (the end of the small intestine) with the colon.

Colon

This is the longest part of the large intestine and is divided into four parts:

  • Ascending colon, located on the right in the abdominal cavity.
  • Transverse colon, crosses from right to left at the top of the abdominal cavity.
  • Descending colon, located at the left of the abdominal cavity.
  • The sigmoid colon, the end of the colon connected to the rectum.

Rectum

The stool is stored until finally ejected through the anus.

Anus

The last part of the large intestine.

The histological depiction of the colon in general is that the Lieberkuhn Kripta contains longer and straighter in the mucosa tunica compared to the small intestine.

The epithelium of the large intestine is cylindrical and contains much more Goblet cells than the small intestine

Lamina Promale Colon is consist of reticular connective tissues and a nodulus lymphaticus. 

As in the small intestine, the tunic of the muscularis mucosa in the colon consists of a circular layer inside and the outer longitudinal layer. Mucosal tunics consist of loose connective tissues, fats, and Meissner plexus. On the outside of the mucosal tunic there is an external and serous tunic,  The serous tunics consist of mesothelium and subserosal connective tissue. 

Large Intestine Structure

Broadly, the colon has a similar wall structure with a small intestine and most other digestive organs. The structure of the colon is composed of the following 4 walls (from outside to inside):

Serosa Layer

It is an outer layer consisting of blood vessels, lymph and nerves. Serosa layer of the colon is a connective tissue that is covered by visceral peritoneum. The serosa layer has small cavities where the serous fluid discharge serves as a lubricant for muscle movement.

Muscle Layer

The muscle layer of the colon is a layer of smooth muscles that work without us knowing. There are two types of muscle fibers, namely the longitudinal muscle fibers (elongated) and the circular muscle fibers. The combination of contraction of these two types of muscles will result in intestinal peristalsis that serves to break down food and bring it to the next digestive organ.

Read also: Facts About The Muscular System You Need To Know

Submucous Layer

It is a loose connective tissue layer containing blood vessels, lymph, nerves and mucous glands. Blood vessels in the submucous layer of the colon play an important role in passing the absorbed foods.

Mucous layer

The mucous layer is composed of simple epithelial cells and thin connective tissues. Mucosal layer has goblet cells that can produce mucus. This mucus is the secretion of all glands found in the colon. The coating of the production is influenced by the secretion and enterocytes hormones, it is often also called intestinal juice.

Large intestine function

Colon functions are:

Absorb water

Most of the food digestion process and nutrient absorption have been resolved in the small intestine. But the colon helps to improve the digestive process by absorbing water. With this, formed material remnants of the digested food are dense to be removed from the body as a feces.

Absorbs vitamins

The next colon function is to help the absorption of vitamins that are formed from the activity of good bacteria that do live in the colon. There are about 700 species of good bacteria that live in the colon and help in maintaining our health.

Some of these good bacteria functions are breaking down the undigested polysaccharide into fatty acids that are easily absorbed by the colon. The fermentation of this undigested polysaccharide produces nitrogen, carbon dioxide, hydrogen sulphide, and methane that is excreted by the body as a flatus (farting).

Bacteria in the colon also produce vitamin K as well as biotin. When we lack intake of this vitamin from food, the production of vitamins by these bacteria will be very helpful to maintain health.

Reduce acidity

Large Intestine Function

The digested food will be broken down by bacteria, but there are bacteria that cause food to become acidic. This colon function will reduce food acidity.

Absorbing food that is not absorbed by the small intestine

In the small intestines of nutrient absorption, sometimes nutrients are left behind. Well, inside this colon will reabsorb nutrients that have not been absorbed by the body.

Strengthens the immune system

It can be proved when experiencing diarrhea. A person who is experiencing diarrhea will defecate many times until the colon is not left. Then the reaction of the body will experience weakness.

Read also: The Causes of Frequent Bowel Movements

Thank you very much for reading Large Intestine: Anatomy, Histology, Structure, and Function, hopefully useful.

Large Intestine: 4 Anatomy, Histology, Structure, and Function

Post in | Last updated: April 4th, 2020 |