Physiology
the science which the bodies of living beings under normal conditions, and of the use of their various parts or organs. It is divided into plant physiology, animal physiology, and human physiology. One of the simplest forms of animal life is seen in the the amœba of pond water or in the white Boston Normal School of Gymnastics corpuscle or leucocyte of the blood. was founded in 1889 to provide for the instruction of teachers of physical edufor the schools, and the system was introduced into the public schools of the city in 1890. Eight States, Illinois, New York, New Jersey, Nevada, Rhode Island, California, Maryland and Delaware , have now passed laws making physical education obligatory in all the schools.
It has been most developed in the Gary school, where 24 per cent. of the time in the elementary grades is devoted to it, with a proportionately diminished time in the higher grade.
Vol. VII-Cyc These simple organisms composed each of a single physiological unit, which is termed a cell, that is to say, there are no organs for the carrying on of the various functions of life, but all take place in the same microscopic semifluid mass of complex organic nature termed the cell protoplasm. All animals, no matter how complex be their structure, resemble this primitive type, for they consist of an aggregation of microscopic cells. In the leucocyte or amœba all kinds of labor proceed in the same cell which imbibes its own food, prepares PHYSIOLOGY its own nutriment from the food so taken in, is capable of moving from place to place, and in the end is capable of reproducing its like by division. In the higher animal by the evolution of different types of cell, which start from the same parent cell initially but develop afterward along different lines, there come to be formed the various different tissues, glands and organs, each with its own specific function to perform for the general welfare of the whole mass or colony of cells constituting the animal or individual. Thus the skeletal system develops for the support and maintenance of form of the whole, the muscular system to bring about the movements of the animal as a whole and of its various parts with respect to one another; the digestive system for preparing the nutriment for the whole system; the vascular or circulatory system with its contained blood for carrying the nutriment so prepared and distributing it to all the various parts; the respiratory system for taking in oxygen from the air, necessary for the combustion of the foodstuffs and for carrying off the carbon dioxide formed by such combustion in the various tissues; the excretory system for the removal of chemical waste products formed in the tissues; and the nervous system for setting the animal tissues in communication with what is passing both in the body and in the external world.
PIACENZA cell is close to a capillary (a thin blood vessel) along which the fluid food flows and as it flows the fluid part or plasma exudes and bathes the tissues. The plasma which has thus passed out of the blood vessels is collected into another system of vessels, the lymphatics, and eventually emptied into one of the great veins. The lymph stream is also the drain into which is thrown by each cell the waste products of its activity. The carbonic acid that is formed in the tissues is carried away by the blood, and escapes out of the system from the lungs. Some of the useless water is also got rid of in the same way, and some more of it is sweated out by the glands in the skin; the rest is filtered out of the blood by the kidneys. There are many other waste matters besides carbonic acid and water. These are to a large extent prepared for excretion in the liver, and to some extent actually taken out of the blood by that organ, being poured into the intestines, mixed with other matters, dissolved in a fluid called BILE (q. v.) They are all taken out of the blood by the kidneys, and cast out of the body along with the water filtered out by the same organs, as urine. For comparative physiology, see the articles on the various functions and groups of animals. Consult works by Loeb, Piersol, Lyle, Cannon, Lamarck, etc.