Structure of the tissue

A fundamental goal in constitutive modelling is to predict the mechanical behaviour of a material under various loading states. A biological tissue is a collection of cells, and extracellular matrices, that perform various specialized functions. There are four basic primary tissues types: muscular, nervous, epithelial and connective. Muscle tissue produces mechanical work through contraction–relaxation. For example, skeletal muscles are responsible for locomotion primarily through voluntary muscle contraction, cardiac muscles provide the active pumping of blood from the heart, and smooth muscles, which are part of the organs of the digestive tract, facilitate peristalsis, propulsion, microcirculation, etc.

Nervous tissue provides communication among organs and systems predominantly by electrical signals. Neurons are responsible for the production and propagation of the waves of depolarization in the myelinated and unmyelinated nerve fibres, smooth muscle syncytia and other cell aggregates. Neuroglial cells are a diverse group of morphoelements that play a supportive, mainly trophic, role.

Epithelial tissue covers the outer and inner surfaces of most of the organs. Various types of cells line the digestive, reproductive and urinary tracts, blood vessels, ducts, etc. They act as a protective barrier and are instrumental in selective regulation of the transport of specific agents and substrates.

Connective tissue includes a diverse set of cells surrounded by a large amount of extracellular matrix. Its main function is to provide a level of mechanical support to the organ.