COMPOSTION OF HUMAN BODY

Almost 99% of the mass of the human body is made up of six elements : OXYGEN, CARBON, HYDROGEN, NITROGEN, CALCIUM, AND PHOSPHORUS.  only about 0.85%  is composed of another five elements: potassium,sulfur, sodium, chlorine, and magnesium. All 11 are necessary for life.

MAJOR CLASSES OF COMPOUND IN THE HUMAN BODY:
       Most of the elements are found within compounds. Water and minerals are inorganic compounds.Organic compounds include fat, protein,carbohydrates, and nucleic acids.

•  WATER: Water is the most abundant chemical compound in living human cells, accounting for 65%  to 90% of each cell. For example,  blood and cerebrospinal fluid are mostly water.

• FAT: The percentange of fat varies from person to person, but even an obese person has more water than fat.                             
• PROTEIN: In a lean male, the percentages of protein and water are comparable. its about 16% by mass. Muscles, including the heart, contain a lot of muscles. Hair and fingernails are protein. skin contains a large amount of protein, too.
• MINERALS: Minerals account for about 6 percent of the body. they include salts and metals. common minerals include sodium, chlorine, calcium, potassium, and iron.
• CARBOHYDRATES: Although humans use the sugar glucose as an energy source, there isnt that much of it free in the bloodstream at any given time. sugar and other carbohydrates only account for about 1% of body mass.
• OXYGEN: Oxygen is the most abundant element in the human body accounting for approximately 65% of a person's mass, Each water molecule consists of two hydrogen atoms bonded to one oxygen atom, oxygen is essential for cellular respiration. 
• CARBON: Carbon is contained in all organic compounds, which is why carbon is the second most abundant element in the body, accounting for about 18% of body mass. Carbon is found in proteins, carbohydrates, lipids, and nucleic acids. Its also found in carbon dioxide.
• HYDROGEN: Atoms are the most numerous type of atom in a human, but because they are so light, they only make up around 10% of the mass. Hydrogen is in water, plus its an important electron carrier.
• NITROGEN: Is about 3.3% of body mass. its found in proteins and nucleic acids.
• CALCIUM: accounts for 1.5% of body mass. its used to build bones and teeth, plus its important for muscle contraction.
• PHOSPHORUS: Is about 1% of the body mass. breaking bonds connecting phosphate molecules is a major component of energy transfer.
• POTASSIUM: is around 0.2%-0.4% of the mass of a person. positively-charged ion in the body.                                                                                                                                                 Other trace elements included metals which are often cofactors for enzymes. Trace elements included in our body.