Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: PART I METABOLISM THE combustible constituents of our body continually undergo chemical changes, in that they are burned by the inhaled oxygen. The products of combustion are removed from the tissues, in which the combustion takes place, by the circulating blood and lymph; one of these products, the carbonic acid gas, is excreted from the body by the lungs; the other products, by glands. That the body may continue to exist, new material for combustion must be supplied to it from without. This is effected by the partaking of nourishment which is made absorbable by digestion, and, after absorption, supplied to the tissues by the blood and then assimilated. Metabolism, therefore, includes the following parts of physiology: 1. The chemical constituents of the body and their physiological importance. 2. Blood, the gases of the blood and respiration, circulation of the blood, respiratory movements, lymph. 3. Secretions. 4. Nutrition, alimentary principles, food, digestion, absorption and assimilation of the digested food. 5. Survey of metabolism as a whole. chapter{Section 4CHAPTER I CHEMICAL COMPOSITION OF THE HUMAN BODY The fifteen elements of which the body is composed are present in about the following proportions: Carbon, 18.5$ Oxygen, 65.0£ Hydrogen, il.0$ Nitrogen, 2.5$ Sulphur, Phosphorus, Chlorine, Iodine, Fluorine, Silicon, Potassium, Sodium, Calcium, Magnesium, Iron,—together The adult human body contains about 3 g iron. Other elements, traces of which are sometimes found, must be regarded as accidental constituents. The body is, therefore, mainly composed of non-metals (metalloids). Oxygen, nitrogen, and, in small quantities, hydrogen are the only free elements; only the free oxygen is of physiological importance. ...