He glucocalix is a carbohydrate enriched layer that covers the exterior of diverse Cell types , particularly bacteria and human cells. This protective coating fulfills several very important functions for the cell.
Basically, glycocalyx is made up of polysaccharide chains (sugars) linked to various protein and lipid molecules, thus forming associations called glycoproteins and glycolipids, respectively. The result is a fibrous and sticky network with the ability to hydrate.
In eukaryotic cells, the composition of glycocalyx may be a factor used for cell recognition.
On the other hand, in the bacterial cells, the glycocalyx provides a protective layer against the factors of the host, in fact, the possession of a glycocalyx is associated with the capacity of the bacteria to establish an infection.
In humans, glycocalyx is found on the membranes of vascular endothelial cells and epithelial cells of the digestive tract.
On the other hand, the bacterial glycocalyx can surround individual cells or colonies, thus forming the so-called bacterial biofilms.
Glucocalix in bacteria
The structural characteristics and chemical composition of the bacterial glycocalyx differs according to the species, but in general this additional coating can come in one of two forms:
Limos
A glycocalyx is considered a layer of silt when the glycoprotein molecules are associated loosely with the cell wall.
However, bacteria that are covered with this type of glycocalyx are protected against dehydration and loss of nutrients.
Capsules
The glycocalyx is considered a capsule when the polysaccharides are more firmly attached to the cell wall.
The capsules have a sticky consistency which, in addition to protection, also facilitates adhesion to the solid surfaces of the environment .
Bacteria that have capsules are considered encapsulated, and generally have a higher pathogenicity (ability to cause disease), because the capsules protect bacteria, including phagocytic white blood cells of the immune system.
Glucocalix in humans
In humans, glycocalyx is very important for vascular function and for the digestive system.
Glucocalyx in the vascular endothelium
The blood vessels are actually small tubes made of cells. The cells inside the tube are called endothelial cells and must resist the pressure of the blood that flows over them constantly.
To resist this, vascular endothelial cells produce a mucilaginous layer. This glycocalyx also has enzymes and proteins that help the cells involved in the coagulation of the blood to adhere to the blood vessels when necessary.
The main function of glycocalyx in the vascular system is to maintain the homeostasis of the endothelium.
The alteration of the structure of the glycocalyx in the vascular endothelium could cause the formation of a blood clot within a blood vessel, obstructing the flow of blood through the circulatory system and in this way having detrimental effects on health.
Glucocalix in the digestive tract
The second best described example of glycocalyx in humans is found in the digestive system. The small intestine is responsible for absorbing all the nutrients that come from the food we eat.
The cells of the small intestine responsible for absorbing nutrients have many small folds called microvilli.
Each of the cells that make up the microvilli it is covered with glycocalyx, which is formed by mucopolysaccharides (long chains of complex sugars) and glycoproteins.
Thus, it provides an additional surface for absorption and also includes enzymes secreted by these cells that are essential for the final steps of the digestion of food.
Every time we eat, there is a risk of ingesting harmful material that can cross the intestinal lining.
Therefore, in addition to the function of digestion and absorption of nutrients, the glycocalyx of the intestinal epithelium must also serve as a protective barrier to filter out harmful products.
Other functions of glycocalyx
Glycocalix also fulfills other functions in defense against infection and cancer, cell adhesion, regulation of inflammation, fertilization and embryonic development.
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