Definition
Definition
Keratin is a protein particularly rich in cystine (a variety of sulfur amino acids made up of cysteine used in the composition of many proteins such as albumin or insulin), very common in humans, but also in animals, and possessing many qualities including its resistance.
La keratinization is the transformation of the superficial layers of the skin (epidermis), or of a mucous membrane (layer of cells covering the inside of hollow organs in contact with the air) which are progressively enriched with keratin.
Generalities
Dead tissues, which perform protective functions, contain keratin:
- Hair and fur.
- Stratum corneum (the most superficial layer of the epidermis made up of dead cells).
- Nails.
- Horns.
- Claws.
- Feathers.
- Oldest boy.
Classification
There are 2 types of keratin:
- La soft keratin which tends to flake (fall off) in scales, having a plastic, translucent nature, and easily retaining water.
- La hard keratin, more compact than the previous one but also more resistant, yellow in color. This variety of keratin does not tend to flaking.
Anatomy
La keratin consists of filament of a particular variety, the protofilaments, having a diameter of 7 to 8 nanometers (billionths of m) and which, for certain organs (hairs), have a symmetrical arrangement of hexagonal shape.
Between the protofilaments is an amorphous material, called "interfilamentous matrix».
Symptoms
physiology
amino acids entering into the composition of keratin varies from one species to another, but also from one organ to another.