collagen

(noun)

Any of more than 28 types of glycoprotein that forms elongated fibers, usually found in the extracellular matrix of connective tissue.

Related Terms

Examples of collagen in the following topics:

  • Connective Tissues: Loose, Fibrous, and Cartilage

    • Fibrous connective tissues contain large amounts of collagen fibers and few cells or matrix material.
    • A cartilage with few collagen and elastic fibers is hyaline cartilage.
    • In contrast, fibrocartilage contains a large amount of collagen fibers, giving the tissue tremendous strength.
    • Loose connective tissue is composed of loosely-woven collagen and elastic fibers.
    • Fibrous connective tissue from the tendon has strands of collagen fibers lined up in parallel.

  • Morphology of Sponges

    • Mesohyl is an extracellular matrix consisting of a collagen-like gel with suspended cells that perform various functions.
    • Some of these more-specific cell types include collencytes and lophocytes, which produce the collagen-like protein to maintain the mesohyl; sclerocytes, which produce spicules in some sponges; and spongocytes, which produce the protein spongin in the majority of sponges.
    • These cells produce collagen to maintain the consistency of the mesohyl.

  • Platelets and Coagulation Factors

    • When the endothelial layer is injured, collagen is exposed, releasing other factors to the bloodstream which attracts platelets to the wound site.

  • Extracellular Matrix of Animal Cells

    • Collagen is the most abundant of the proteins.

  • Physiological Processes in Sponges

    • In gemmules, an inner layer of amoebocytes is surrounded by a layer of collagen (spongin) that may be reinforced by spicules.
    • The collagen that is normally found in the mesohyl becomes the outer protective layer.

  • Cell Types in Bones

    • Osteoblasts, which do not divide, synthesize and secrete the collagen matrix and calcium salts.

  • Bone Remodeling and Repair

    • Fibroblasts produce collagen fibers that connect the broken bone ends, while osteoblasts start to form spongy bone.

  • Arteries, Veins, and Capillaries

    • Veins and arteries both have two further tunics that surround the endothelium: the middle, tunica media is composed of smooth muscle, while the outer tunica externa is connective tissue (collagen and elastic fibers).

  • Types and Functions of Proteins

    • For example, hemoglobin is a globular protein, which means it folds into a compact globe-like structure, but collagen, found in our skin, is a fibrous protein, which means it folds into a long extended fiber-like chain.

  • Control of Metabolism Through Enzyme Regulation

    • Vitamin C is a coenzyme for multiple enzymes that take part in building collagen, an important component of connective tissue.