Mineral Metabolim-

Mineral elements present in the body are supplied by the diet and are of two types-
· principal elements
· trace elements

Water balance-

Water is most common and abundant compound of all living system. An equilibrium is maintained between the intake and the loss of water from body. The regulatory mechanism of body water is influenced in addition to other factor by certain hormones, such as ADH oxytocin and aldosterone.

Acid number of fats-

Naturally occurring oils and fats are the esters of higher fatty acids with the trihydric alcohol glycerol and are enormously found in nature.
Chemically, fats are identical with oils in all respect except that the fats are solid at room temperature whereas oils are liquid.
Fat is the reserve food material in human body. It acts as insulator for the loss of body heat and also serves as a padding material for protecting internal organs.
Physical properties of fats-
Fats are insolublein water and soluble in organic solvent such as ether, chloroform, benzene. Melting point is low and pure fats have no colour, odour or taste. The specific gravity of solid fat is about 0.86.
Chemical properties-
1)Hydrolysis-
Hydrolysis of fats takes place by lipase producing fatty acids and glycerol. Phosholipase attack the ester linkages of phosholipids.
2) Saponification-
Hydrolysis of fatby alkali is called saponification. The products are glycerol and the alkali salts of fatty acids which are called soaps.
3)Halogenation-
Fats react with halogens to give addition product.
4)Rancidity-
Nearly all natural fats are oxidized when expose to air, light, moisture, particularly if warm, developing an unpleasant odour and taste. This happens due to the formation of peroxides at the double bond of unsaturated fatty acids. Vitamin E is an important natural antioxidant.

Triglycerides

Triglycerides are the ester of fatty acids with glycerol. They are the best reserve food material in the human body. They act as insulator for the loss of body heat. The chemical structure of triglycerides consist of three different molecules of fatty acids with one molecule of glycerol. They are insoluble in water and soluble in organic solvents such as ether, chloroform, benzene. Their meltin points are low. Triglycerides on hydrolysis give three molecules of fatty acids and glycerol.

LIPID-

Lipids are the heterogeneous group of organic compounds related to fatty acids which are insoluble in water and soluble in organic solvents like ether, chloroform and benzene. It occurs widelyin plant and animal kingdom,eg. Oils, fats, waxes. Lipids are important dietary constituents on account of high caoric value.
IMPORTANT BIOLOGICAL FUNCTION-
1) In the body, fat serves as an efficient source of energy when stored in adipose tissue.
2) Lipid serves as an insulating material in the subcutaneous tissue and around certain organ.
3) Lipids provide essential fatty acids, which are not synthesized by human body.
4) Lipids are the carriers of fat-soluble vitamin.
5) Lipids are used to form substances essential for maintaining cellular integrity such as lipoproteins and glycolipids, in combination with proteins and carbohydrates respectively.
6) It provides building blocks for different high molecular weight substance.
7) They produce metabolites through oxidation in the tissues, which are used in the interconversion of substances.