Oxygen
Carbon
Hydrogen
Explanation:
Oxygen :
Oxygen is the most abundant element in the human body. It makes up 65 percent of the total weight of a person. For a person with a weight of 155, about 94 pounds of her total weight would be made of the element oxygen. This is due mainly to the body's water content. Water makes up the majority of the human body, and the two elements that make up water are oxygen and hydrogen. Oxygen is also present in both our inhalations and exhalations. When breath in air from the surrounding atmosphere, some of it is oxygen. When we exhale, we breathe out the molecule carbon dioxide, which is made of the elements carbon and oxygen.
Carbon :
Carbon is the second most abundant element in the human body, and makes up about 18 percent of your total weight. For a person weighing 170, 35 pounds of that weight is from the element carbon. Carbon forms the backbone of DNA, which present in most of the cells present in the human body. Carbon is also present in the sugar molecules your body uses for energy. We consume carbon from the food we eat, and release it back into the environment when we exhale.
Hydrogen :
Hydrogen is the most abundant element in the universe, and is also the smallest element. It makes up about 9 percent of the total weight of the human body. A person who weighs 170 pounds gets about 15 pounds of that weight from hydrogen. Two hydrogen atoms are present in every water molecule. Hydrogen is found in many other biological molecules in the human body. The present of hydrogen atoms on a fatty acid molecule determines if the fat is saturated or not.
Other Abundant Elements :
Beyond these three elements, the next three elements that occur in greatest abundance in the human body are nitrogen, calcium and phosphorous. Together, these elements make up about six percent of the total weight of the human body. Nitrogen is found in the proteins, while calcium and phosphorous have their greatest concentrations in your bones and teeth. Phosphorous is also present in the DNA chain and is an essential component to the membranes enclosing your cells.
