Body and Its Defenses e-bog

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. It is the purpose of this volume to present such material on physiology, hygiene, and sanitation as may be of practical service to young people. For this reason function is emphasized rather than structure, and the laws of health receive more attention than the mechan ical operation of bone, muscle, gland, and tissue. In the earlier chapters of the book stress of teaching is laid on right habits of sitting, of standing, and of walk ing; on the relation of the school desk to spinal curva ture; on laws of growth and their relation to correct habits of posture; on the development of muscular vigor; and on the renewal of the tissues of the body. Attention is also called to the source of all muscular energy - the blood. Simple tests, easily applied, explain the cause of rapid and slow heartbeat and Show how the power of the heart and of the lungs may be increased gradually. Reasons are given why the untrained heart should not be greatly taxed, and why extreme breath lessness is objectionable. The effect of alcohol on the heart and on the arteries is made plain, and the effect of tobacco on the action of the heart is illustrated by means of the sphygmograph.