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Water serves a great variety of functions in the body. It provides the fluid medium in which the chemical reactions of the cells take place; it furnishes the major transport medium for distributing oxygen, nutrients and other substances as well as carrying away waste products. It is important in excretion of wastes through the kidney etc. and it plays a key role in the body's temperature-control mechanisms. The water content of the tissues is continuously monitored in the brain.
Inorganic Salts : 4 percent of the weight of the body is comprised of inorganic salts—partly in dissolved form dissociated into ions and partly in combination with organic compounds.
Sodium and chloride ions are the most abundant ions in the body fluids; within the cell, potassium and phosphate ions are the major inorganic constituents. Calcium phosphate is the major constitutent of bones. Various other ions in smaller amounts, some in barely detectable traces are also present. Some of these trace elements are constituent of key enzyme systems, wihout which the normal reactions in the body could not take place. The acid-base balance, coagulation of blood, transport of oxygen and carbon dioxide, nerve conductivity, muscle contraction and coordination of metabolic activities-these all need inorganic salts.
Carbohydrates : Carbohydrates contain three elements : carbon, hydrogen and oxygen combined in the ratio CxH2yOy. They include sugars and starches and are the major sources of energy. Glucose is the form of simple sugar that is carried in the blood. It is an essential nutrient for all body-cells, particularly brain-cells. Starch consists of many glucose-units linked together. Whatever glucose is not immediately needed is synthesized into glycogen, which is stored within liver and muscle tissues.
1. An atom that loses its neutrality and becomes a charged particle is
called an ion
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