**General Notes on Biomechanics and Mechanobiology**

**1** 

**Mechanical Properties of Living Cells and** 

**Tissues Related to Thermodynamics,** 

**Experiments and Quantitative** 

*Department of Mechanics, Faculty of Applied Sciences* 

Miroslav Holeček, Petra Kochová and Zbyněk Tonar

*Department of Histology and Embryology, Faculty of Medicine in Pilsen* 

Although Galileo Galilei laid down the fundamentals for a mathematical description of natural processes, a long time passed before living organisms became a focus in physics. Given the high-spirited concept from René Descartes, living organisms were considered subject to the same universal laws as all objects. However, this approach did not provide scientists with an apparatus for systematically describing the physics of living matter. Isaac Newton's examination of physical reality was based on analysis of the forces that cause movement of objects. Although he developed a very efficient and fruitful mathematical apparatus, living organisms appeared as "black boxes" therein. Terms such as "trajectory" and "force" became highly problematic when attempting to describe such phenomena as the growth, assembly, and physical activities of complex biological systems. These problems became apparent during the 20th century with advances in thermodynamics, molecular physics, computer simulations, and highly sophisticated experimental and imaging

From the perspective of physics, living cells are considered physical systems, i.e., material structures composed of atoms and molecules governed by the laws of physics. A living cell becomes material with certain rheological properties. Its molecular structure is described using terms from macromolecular chemistry, polymer physics, statistical mechanics, and thermodynamics. Most of the biological attributes for living matter are reduced or neglected on purpose, as they are typically undefined using these physical methods. However, even physicists must reflect the enormous complexity of biological systems. When considering a living cell as a "material", we cannot ignore that the phenomena, such as the "material", is able to move spontaneously, and cells can migrate through pores and avoid barriers while simultaneously changing their shape as well as their viscoelastic and rheological properties. Moreover, these physical objects of interest are growing and multiplying in number, and

**1. Introduction** 

methods.

**Physics and living matter**

**Morphology – A Review** 

*University of West Bohemia, Pilsen* 

*Charles University in Prague, Pilsen* 

 *Czech Republic* 
