Elastin is able to stretch and rebound thanks to the structure of the elastin molecules. An elastin fibre consists of a number of fibrils grouped together, and an elastin fibril is formed by multiple elastin molecules.
Elastin is formed of peptides, fibroblasts, and amino acids, which are structured in a particular shape that determines its function. Elastin stretches and rebounds thousands of times a day without us knowing. It happens every time we smile, frown, raise an eyebrow.
Loss of skin elasticity is known as elastosis.