In common language it includes the principles and facts of the origin, development, structure, functions and distribution of plants and animals. Life exists because of the exercise of organs. Physiologists study functions, the action of organs. Physiology deals with the processes, activities and the phenomena incidental to life, the characteristic actions which constitute life, those qualities which determine a living organism from one which does not live, those actions which depend upon an intelligence. The body is incapable of creating new forces.
Force is that which originates or arrests motion.
Vital force is the energy which gives life or action to an organism, the vital power which distinguishes living matter from the dead. Organic force is the inherent vigor latant in an organ. Nerve force is the power or ability to conduct impulses. Reserve force is the energy which is stored in an organ or organism that is not required for normal functionating. Intelligent actions are the expressions of the sum total of life.