Question

73.Structural proteins of connective tissue: examples, structure and functions.

(please more explanatıon Im medicine student) thank you...

Answer 1

The connective tissue is abundantly oresent in the body and mainly functions in providing structural integrity, binding, support, insulation and forms the core part of extracellular matrix. The connective tissue is made up of cells suspended in the ground substance along with fibres. The ground substance and fibers make up the ECM. Ground sunstance is a viscous fluid that fills ups the spaces between the cell It contains cell adhesion molecules and peptidoglycan that allow cell to cell communication. The major structural proteins of connective tissue include:

1. Collagen fibers that are fibrous proteins secreted into the extracellular space which provide high tensile strength to the ECM. Collagens comprise of over 40 different types of proteins but mainly consist of 4 major type.

• Type I collagen forms fibers and is found in most connective tissues with bone, ligaments, tendon and skin.
• Type II collagen forms fibers are less organized than type I fibers and are found mainly in cartilage.
• Type III collagen forms much thinner fibers than type I. This type makes up reticulin fibers in organs and help organize cells within organs.
• Type IV collagens form branched networks and help organize the basement membrane.

2. The thin and long elastic fibers form branching network in the ECM and help to stretch and recoil. Elastin is the main functional component of elastic fibers. Elastin protein are crosslinked together to form a network. Tensile forces which stretch elastin protein into an extended conformation when removed, return to disorganized conformation, forming a recoil force.

3. Proteoglycans form a porous, gel-like substance that maintains diffusion of small molecules and resists compressive forces. They are proteins with long sugar side chains and repeated disaccharide units called glycosaminogans. Proteoglycans can bind to specific metabolites and signaling molecules participating in cell cell communication.

4. Reticular fibers are short, fine collagenous fibers which can branch extensively to form a delicate network.

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