27.5: Elastin is Responsible for Tissue Elasticity

Elastic fiber contains the protein elastin along with lesser amounts of other proteins and glycoproteins. The main property of elastin is that it will return to its original shape after being stretched or compressed. Elastic fibers are prominent in elastic tissues found in skin and the elastic ligaments of the vertebral column.

Ligaments and tendons are made of dense regular connective tissue, but in ligaments not all fibers are parallel. Dense regular elastic tissue contains elastin fibers and collagen fibers, allowing the ligament to return to its original length after stretching. The ligaments in the vocal folds and between the vertebrae in the vertebral column are elastic. Dense irregular elastic tissues give arterial walls the strength and the ability to regain original shape after stretching

While older adults are at risk for tendinitis because the elasticity of tendon tissue decreases with age, active people of all ages can develop tendinitis. Young athletes, dancers, and computer operators; anyone who performs the same movements constantly is at risk for tendinitis.

Elastic cartilage contains elastic fibers as well as collagen and proteoglycans. This tissue gives rigid support as well as elasticity. Tug gently at your ear lobes, and notice that the lobes return to their initial shape. The external ear contains elastic cartilage.

This text is adapted from Openstax, Anatomy and physiology 2e, Section 4.3: Connective tissue supports and protects.

Tissues such as skin, lungs, and blood vessels must be strong as well as elastic to work properly. Tissues owe their elastic properties to the elastic fibers present in their extracellular matrix.

Each of these fibers is composed of tropoelastin aggregates assembled on the microfibrils.

Tropoelastins are the precursors of elastin molecules, made up of alternating hydrophobic and cross-linking domains.

The hydrophobic motifs, which cover more than 80 percent of the total protein, allow elastin to self-associate, stretch, and recoil when needed. The cross-linking domains allow cross-links to form between neighboring tropoelastin molecules.

Together, these structural features allow fibres to stretch more than fivefold compared to a rubber band of a similar cross-section.

As elastin fibers mature, the elastin aggregates form an amorphous core surrounded by microfibrils. These elastin structural features confer remarkable tissue elasticity.