Elements in the human body

Phosphorus. Eighty-five percent of the phosphoms, the second most abundant element in the human body, is located in bones and teeth (24,35). Whereas there is constant exchange of calcium and phosphoms between bones and blood, there is very Httle turnover in teeth (25). The Ca P ratio in bones is constant at about 2 1. Every tissue and cell contains phosphoms, generally as a salt or ester of mono-, di-, or tribasic phosphoric acid, as phosphoHpids, or as phosphorylated sugars (24). Phosphoms is involved in a large number and wide variety of metaboHc functions. Examples are carbohydrate metaboHsm (36,37), adenosine triphosphate (ATP) from fatty acid metaboHsm (38), and oxidative phosphorylation (36,39). Common food sources rich in phosphoms are Hsted in Table 5 (see also Phosphorus compounds). 

Table 1.1 Percentage Composition of Selected Elements in the Human Body...

After iron, zinc is the second most abundant trace element in the human body an average adult has 3 g of Zn, corresponding to a concentration of about 0.6 mM. Some 95% of zinc is intracellular. It is essential for growth and development in all forms of life, and has been proposed to have beneficial therapeutic and preventative effects on infectious diseases, including a shortening of the length of the common cold in man. 

As hydrogen is the most common element in the human body, it is not surprising that nuclear magnetic resonance has found applications in the field of medicine as magnetic resonance imaging or MRI. 

Selenium is an essential trace element in the human body. This nutrient is an important part of antioxidant enzymes that protect cells against the effects of free radicals that are produced during normal oxygen metabolism. Selenium is also essential for normal functioning of immune system and thyroid gland. 

The other metallic elements in the human body amount to less than 1 g each, but at least seven of them play essential roles. They include copper (100 mg), manganese (20 mg), and cobalt ( 5 mg). Others, such as chromium (<6 mg), tin, and vanadium, have only recently been shown essential for higher animals.156157 Nickel, lead, and others may perhaps be needed. 

Yukawa M, Suzuki-Yasumoto M, Amano K, et al. 1980. Distribution of trace elements in the human body determined by neutron activation analysis. Arch Environ Health 35 36-44. 

The neutral isotope of iodine is an essential element in the human body most of the iodine-127 is located in the thyroid gland. Iodine s radioactive isotope, iodine-131, is readily absorbed in the body, where it becomes concentrated in the thyroid gland and may produce cancers. Exposure to radioactive iodine is an increasing concern since it is produced by fission reactions in nuclear reactors and by nuclear weapons tests. 

The role iron plays in the lives of humans is significant. Iron is primarily used in the production of steel, and it is an essential element in the human body, where it is part of the protein hemoglobin, which is responsible for carrying oxygen. Iron s two principal oxidation states are Fe (III) and Fe (II), and a complex cycle that is responsible for the conversions between the two forms exists in na-... 

Name at least three elements in addition to those shown in the table that you would expect to find in the list of the top ten elements in the human body. Explain your choices. 

Copper is the third most abundant metallic element in the human body, following iron and zinc. It also occurs in all other forms of life and it plays a role in the action of a multitude of enzymes that catalyze a great variety of reactions. There are two cross-cutting ways to classify the copper-containing enzymes (1) According to the structural and spectroscopic characteristics of the copper complex at the active site. (2) According to the function of the enzyme. We shall base discussion on the first of these, with allusions to function as we go along. 

The distribution of elements in living materials is very different from that found in the earth s crust. Table 18.2 shows the distribution of elements in the human body. Oxygen, carbon, hydrogen, and nitrogen form the basis for all biologically important molecules. The other elements, even though they are found in relatively small amounts, are often crucial for life. For example, zinc is found in over 150 different biomolecules in the human body. 

Tab. 3.14 Essential and non-essential trace elements in the human body...

Calcium is the fifth most common element in Earth s crust. Its abundance is estimated to be about 3.64 percent. It is also the fifth most abundant element in the human body. 

Carbon is the fifth most common element in the universe, by weight, and the fourth most common element in the solar system. It is the second most common element in the human body after oxygen. About 18 percent of a person s body weight is due to carbon. 

Select one of the essential elements. Check your school library or the Internet for details about the role of each element in the human body and for any guidelines and recommendations about the element. 

The average amounts of some essential and non-essential elements in the human body are shown in Table 2.1. This shows that the weights of some of the essential elements in the body vary by six or more orders of magnitude. Oxygen, at 45 kg, is by far the most abundant element with the majority being present as one simple inorganic compound water. Some of the elements listed in Table 2.1, and marked with an asterisk, have no known beneficial function and are present in the body simply because they are present in rocks and soils and find their way into water and foodstuffs and from thence into the human body many of these elements are present in only minute quantities. 

The accompanying table lists the essential elements in the human body. Of special interest are the trace elements, such as iron (Fe), copper (Cu), zinc (Zn), iodine (I), and cobalt (Co), which together make up about one percent of the body s mass. These elements are necessary for biological functions such as growth, transport of oxygen for metabolism, and defense against disease. There is a delicate balance in the amounts of these elements in our bodies. Too much or too little over an extended period of time can lead to serious illness, retardation, or even death. 

O How many of the Top Ten elements in the human body are also Top Ten elements in the earth s crust, ocean, and atmosphere What are these elements ... 

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