What is fiber


Latin: fibra
English: fiber

1 definition

Fibers are structural components of the extracellular matrix consisting of elongated protein polymers.

In a broader sense, the term fiber is used in medicine as a macroscopic description for all elongated anatomical structures that have a significantly smaller diameter in relation to their length, e.g. muscle fibers, tendon fibers or nerve fibers.

2 classification

There are two different types of fiber:

Reticular fibers (Fibrae reticulares) are still listed as a separate fiber type in older textbooks. However, they are type III collagen. With a diameter of 20-40 nm, the fibers are significantly thinner than other collagen fibers. They occur mainly in the reticular connective tissue, but also in other tissues.

3 collagen fibers

Collagen fibers are made up of collagen molecules. They occur ubiquitously in the body and guarantee the tensile strength of the tissue. From a biochemical point of view, they have a triple-helix structure with three alpha chains in which every third amino acid is glycine. Of the around 25 different types of collagen, type I, II, III and IV collagens are particularly important.

4 elastic fibers

As the name suggests, elastic fibers can be stretched reversibly. They consist of elastin and microfibrils, which in turn are composed of glycoproteins (e.g. fibrillin, fibulin). Elastic fibers are found primarily in tissues where extensibility is an important functional property, e.g. in the lungs, in the skin and in arteries of the elastic type.