Zoology: Animals
Molecules
Collagen
Collagen (/ˈkɒlədʒən/) is the main structural protein in the extracellular matrix of a body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals. 25% to 35% of a mammalian body's protein content is collagen.
In collagen, amino acids are bound together to form a triple helix of elongated fibril known as a collagen helix. The collagen helix is mostly found in connective tissue such as cartilage, bones, tendons, ligaments, and skin. Vitamin C is vital for collagen synthesis, while Vitamin E improves its production.
Depending upon the degree of mineralization, collagen tissues may be rigid (bone) or compliant (tendon) or have a gradient from rigid to compliant (cartilage). Collagen is also abundant in corneas, blood vessels, the gut, intervertebral discs, and the dentin in teeth. In muscle tissue, it serves as a major component of the endomysium. Collagen constitutes 1% to 2% of muscle tissue and accounts for 6% of the weight to skeletal muscle. The fibroblast is the most common cell creating collagen in a body. Gelatin, which is used in food and industry, is collagen that was irreversibly hydrolyzed using heat, basic solutions, or weak acids.
Collagen is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins, such as enzymes. Tough bundles of collagen called collagen fibers are a major component of the extracellular matrix that supports most tissues and gives cells structure from the outside, but collagen is also found inside certain cells. Collagen has great tensile strength, and is the main component of fascia, cartilage, ligaments, tendons, bone and skin. Along with elastin and soft keratin, it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. It strengthens blood vessels and plays a role in tissue development. It is present in the cornea and lens of the eye in crystalline form.
Wound healing
Collagen is one of the body's key natural resources and a component of skin tissue that can benefit all stages of wound healing. When collagen is made available to the wound bed, closure can occur. Wound deterioration, followed sometimes by procedures such as amputation, can thus be avoided.
Collagen is a natural product and is thus used as a natural wound dressing and has properties that artificial wound dressings do not have. It is resistant against bacteria, which is of vital importance in a wound dressing. It helps to keep the wound sterile, because of its natural ability to fight infection. When collagen is used as a burn dressing, healthy granulation tissue is able to form very quickly over the burn, helping it to heal rapidly.
Throughout the four phases of wound healing, collagen performs the following functions:
- Guiding function: Collagen fibers serve to guide fibroblasts. Fibroblasts migrate along a connective tissue matrix.
- Chemotactic properties: The large surface area available on collagen fibers can attract fibrogenic cells which help in healing.
- Nucleation: Collagen, in the presence of certain neutral salt molecules, can act as a nucleating agent causing formation of fibrillar structures.
- Hemostatic properties: Blood platelets interact with the collagen to make a hemostatic plug.