Essential and Trace Elements in Bioligical System

Out of 109 known elements 30 elememts are believed to be essential for normal growth and survival of living organism. nineteen of the 30 are trace elements, out of which 12 are transition metals. 

The elements that are required in relatively large amounts (quantities) are called

macronutrients and the elements which are required in small quantities are called

micronutrients

Classification of the Essential Elements

1. Buik structural elements: H, C, N, O, P, S

2. Macrominerals: Na, K, Mg, Ca, Cl

3. Trace elements Fe, Zn, Cu

Ultratrace elements: Non metals: F, I, Se, Si, As, B

                                    Metals: Mn, Mo, Co, Cr, V, Ni, Cd, Sn, Pb, Li

These 30 essential elements have been classified into the six bulk or structural

elements, five macronutrients and 19 trace elements. The 19 essential trace elements

include the three prominent biological active metals - iron, zinc and copper. All the

remaining essential elements are considered as ultratrace since they involve less than 10 mg

in adult human.

Criteria for Essential Elements

1. A physiological deficiency appears when the element is removed from purified diet.

2. The deficiency can be relieved by the addition of one specific element.

3. A specific biochemical function is associated with a particular element.

The simplest definition of an essential element is that, it is an element required for

the maintenance of life, its absence results in death or a severe malfunction of the

organism