Page:Structure and functions of the body; a hand-book of anatomy and physiology for nurses and others desiring a practical knowledge of the subject (IA structurefunctio00fiskrich).pdf/17

 STRUCTURE AND FUNCTIONS OF THE BODY.

CHAPTER I.

COMPOSITION AND GENERAL STRUCTURE OF THE BODY.

Anatomy is the study of the physical structure and physiology the study of the normal functions of the human body.

Chemical Constitution of the Body.—In the body only twenty elements have been found. These include carbon, oxygen, hydrogen, nitrogen, sulphur, phosphorus, calcium, magnesium, manganese, chlorin, potassium, and fluorin. For the most part they appear in very complex and highly unstable combinations, though oxygen and nitrogen may be said to exist uncombined in the blood, alimentary canal, and lungs. Hydrogen also occurs in simple form in the alimentary canal, but as the result of fermentation, not as an element of the body.

Of the organic compounds some contain nitrogen and some do not. The most important of the former are the proteins, which are found only in living bodies and consist of carbon, hydrogen, oxygen, nitrogen, and sulphur combined in very similar proportions. The important proteins in the body are the serum albumen and fibrin found in the blood, myosin in muscle, globulin in the red blood-corpuscles, and casein in the milk. Similar to the proteins but capable of passing through membranes