Re-absorbing nitrogen

The most important elements to life are carbon, hydrogen, oxygen, and nitrogen — the CHON atoms — as well as sulfur and phosphorus. These elements are combined in hundreds of ways to construct the building blocks of life, such as carbohydrates, fats, proteins, and nucleic acids. 

The d-block elements such as iron (Fe), zinc (Zn), and copper (Cu) are needed in smaller quantities and are found as metallo-enzymes, such as hemoglobin in your blood that transports oxygen to your cells (see Climbing Aboard the 

Oxygen Transport earlier in this chapter), and others that are responsible for different electron-transfer and acid-base reactions in the body. 

Consider the statement, You are what you eat. You are what your food eats, too. For example, plants convert water and soil into fruits and vegetables that contain the minerals and elements from where they grow. These minerals and elements then pass along the food chain to us. Essentially, we eat the matter that makes up our environment. By virtue of these plants our bodies are built from the same elements that are found in the soil and water. We are of this planet, and not surprisingly, we share a similar chemical composition with both the Earth s crust and the oceans, but especially the oceans — from whence we came. This can clearly be seen in Table 17-1. 

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