Iron And Your Body

IRON AND YOUR BODY Blood and rusty metal are both red in colour for the same reason — the strong attraction between iron and oxygen. These two naturally occurring elements — one a heavy metal and the other a gas found in the air — combine together to form red coloured compounds. In the human body the combination of these 2 elements is essential for life. The main role of iron in the body is in the red blood cells. Here it combines with a protein to form a substance called haemoglobin. When we breathe in, oxygen in our lungs is attracted to the iron in haemoglobin and combines with it to form oxyhaemoglobin. This is transported around the body by the blood cells, and oxygen is released wherever it is needed to allow the conversion of carbohydrates (sugars) into energy. This is why blood in the arteries is bright red, whereas blood in the veins (which return blood to the heart and lungs for a further dose of oxygen) is darker in colour. Lack of iron in the body is known as iron deficiency. It is easy to see how such a deficiency can cause a general lack of energy, and tiredness. Iron in the Body The Body as a Chemical System: Chemical Elements that Make Up the Body What are our bodies made of, and how do they work? These questions are fundamental to the study of medicine and to many chemists, biologists, and engineers. We know that our bodies are matter, and thus must be composed of atoms that have been specially arranged to produce the molecules and larger structures that sustain our lives. We know that the properties of an atom (e.g., size, electronegativity, number of valence electrons) determine how that atom will interact with other atoms; furthermore, the properties and reactions of molecules depend on the properties and interactions of the atoms in the molecules. Hence, to study the human body as a complex organization of molecules that undergoes a wide array of interrelated chemical reactions, we should begin by asking one of the most basic questions about any system of molecules: What sort of atoms does the system contain? The complete answer to this question will have two main parts: 1) what elements do the atoms represent, and 2) what interactions are found between the atoms (because the properties of a given atom can be altered by interactions with other atoms). Hence, our discussion of the human body as a chemical system begins by answering the question, "What type of atoms does the body contain?" Of the more than 100 chemical elements known to scientists today, only a relatively small number of these elements are found in the human body. In fact, only 24 different elements are thought to be essential to the human body. (Other elements, such as mercury, are sometimes found in the body, but do not perform any known essential or beneficial function.) The largest elemental components of the body, by mass, are oxygen (65%), carbon (18%), hydrogen (10%), and nitrogen (3%). The other elements in the body, such as calcium, phosphorus, iron, and copper, are known to physiologists as mineral elements and trace elements. Although these elements make up a much smaller percentage of the mass of the body than oxygen, carbon, hydrogen, and nitrogen, the mineral and trace elements are vital to the body's proper functioning. These elements must be present in the body in the proper amounts, and they must be available to react with other elements to form critical molecules and participate in important chemical reactions. In this tutorial, we will describe the importance of one essential trace element in the body, iron. Although iron comprises only 0.008% of the body's mass (approximately 6 g for a 160-lb (75-kg) adult male), we cannot live without this important element in our bodies. The Crucial Role of Iron in the Body You learned from the "Hemoglobin and the Heme Group: Metal Complexes in the Blood" tutorial that iron is necessary for oxygen transport in the blood. Recall that iron is the central atom of the heme group, a metal complex that binds molecular oxygen (O2) in the lungs and carries it to all of the other cells in the body (e.g., the muscles) that need oxygen to perform their activities. Without iron in the heme group, there would be no site for the oxygen to bind, and thus no oxygen would be delivered to the cells (which would result in the cells dying). In addition to hemoglobin, other important proteins in the body that contain heme groups (and therefore contain iron) include myoglobin, which takes oxygen from hemoglobin and allows the oxygen to diffuse throughout the muscle cells, and the cytochromes, which supply the body with its energy currency. (You will learn more about cytochromes in the Chem 152 tutorial, "Energy for the Body: Oxidative Phosphorylation".) Other proteins, such as those needed for DNA synthesis and cell division, also rely on iron. Furthermore, iron is used to help produce the connective tissues in our body, some of the neurotransmitters in our brain, and to maintain the immune system. Hence, iron is necessary for allowing the cells that need oxygen to obtain O2, for supplying the body with a reliable source of energy, and for maintaining several other important structures and systems in the body. Iron Disorders Because iron plays such a crucial role in the body, it is important for us to maintain an adequate supply of iron to form hemoglobin and the other molecules in the body that depend on iron to function properly. Yet, our bodies continually lose iron (in small amounts) through everyday process such as urination, defecation, sweating, and sloughing off skin cells. Bleeding, particularly menstrual bleeding in women, contributes to further loss of iron from the body. To compensate for these losses and to maintain an adequate supply of iron, we should consume approximately 18 mg of iron daily. Certain conditions, including heavy bleeding and pregnancy, further increase the requirement for iron consumption. Good dietary sources of iron include red meat, liver, egg yolk, beans, nuts, and fortified cereals. When the body's supply of available iron is too low, a condition known as iron deficiency results. People with iron deficiency cannot produce an adequate amount of hemoglobin to meet their body's oxygen-transport needs. When the deficiency becomes severe (so that there are too few circulating red blood cells or the hemoglobin content of these cells is very low), the condition is diagnosed as iron-deficiency anemia. The most common symptoms of iron-deficiency anemia are tiredness and weakness (due to the inadequate oxygen supply to the body's cells) and paleness in the hands and eyelids (due to the decreased levels of oxygenated hemoglobin, which is red-colored). Iron-deficiency anemia can be treated with iron supplements, and by adopting strategies to improve the body's absorption of the iron in the supplements (e.g., taking iron with vitamin C, which enhances absorption, but not with milk, which limits absorption). It is also possible to have too much iron deposited in the body tissues. This condition is known as iron overload. If the iron overload becomes severe (usually when the total amount of iron in the body exceeds 15 g), the condition is diagnosed as hemochromatosis. Hemochromatosis can result in serious damage to the body's tissues, including cirrhosis of the liver, heart failure, diabetes, abdominal pain, and arthritis. A recessive genetic mutation can put some people (e.g., those of Irish or Celtic descent) at a higher risk for developing hemochromatosis. Treatment for hemochromatosis consists of removing blood from the patient to decrease the amount of iron in the body, and treating the symptoms (e.g., liver disease and diabetes). The human body requires iron to function properly. For example, iron is used in the production of hemoglobin in red blood cells. Iron in hemoglobin attracts oxygen molecules, allowing the blood to carry oxygen to body cells. Red blood cells are constantly being replaced, so it is important that there is a constant supply of iron in our diets. The iron in the cereal is pure iron-the same kind of iron that is found in nails and automobiles. That's why it was attracted to the magnet! It is mixed into the cereal batter along with many other additives. The very tiny pieces of iron that you saw react quickly with HCl and other chemicals in the digestive tract, changing to a form that is more readily absorbed by the body.