Biomechanics, or biological mechanics, uses the principles of mechanics to investigate the effects of energy and forces on biological matter and/or material systems in order to model and predict the mechanical behavior of a living system. Biomechanics is often broken down into two aspects: biofluid mechanics and biosolid mechanics, where biofluid mechanics deals with the properties and movement of fluids under the influence of a force while biosolid mechanics deals with the properties and movement of solids. A typical focus is the cardiovascular system and blood’s flow properties. Biomechanical engineers also study the flow of fluids in the body and the transfer of chemical substances across membranes and synthetic materials. Biomechanics also includes the study of motion, material deformation, and fluid flow. For example, studies of the fluid dynamics involved in blood circulation have contributed to the development of artificial hearts, while an understanding of joint mechanics has contributed to the design of prosthetic limbs.