Hemoglobin carrying oxygen

Anemia maybe one cause of cancer-related fatigue. In its mission to search out and kill cancer cells, chemotherapy and other treatments often destroy rapidly dividing healthy cells, particularly those in the bone marrow, where we manufacture red and white blood cells and platelets. A protein in red blood cells (hemoglobin) carries oxygen throughout the body, and people with anemia may get less... 

During the functional stage, hemoglobin carries oxygen to the tissues. Proliferation, specialization, and function occur in sequence, but the cellular stages overlap proliferating cells or reticulocytes, for example, synthesize hemoglobin. 

Heme The iron-bound porphyrin that, as part of the protein hemoglobin, carries oxygen in blood. 

We have already encountered the protein rhodopsin, the photoreceptor that generates and transmits nerve impulses in retinal cells (Real Life 18-2). Other proteins serve for transport and storage. Thus, hemoglobin carries oxygen iron is transported in the blood by transferrin and stored in the liver by ferritin. Proteins play a crucial role in coordinated motion, such as muscle contraction. They give mechanical support to skin and bone they are the antibodies responsible for our immune protection and they control growth and differentiation—that is, which part of the information stored in DNA is to be used at any given time. 

Iron is indispensable in the human body (see Mineral nutrients). The average adult body contains 3 grams of iron. About 65% is found in hemoglobin, which carries oxygen from the lungs to the various parts of the body. Iron is also needed for the proper functioning of cells, muscles, and other tissues (4). 

Cell-Free Hemoglobin. Hemoglobin seems to be the logical choice for a red cell substitute because of its high capacity to carry oxygen (Fig. 

Carbon monoxide, or CO, is a highly toxic chemical that chemically binds to hemoglobin, rendering it incapable of carrying oxygen to the tissues of the body. CO is produced by the incomplete combustion of fossil fuels. Carbon monoxide levels across the United States fell, on average, by 39 percent between 1989 and 1998. 

Carbon monoxide poisoning results when carbon monoxide replaces oxygen bound to hemoglobin. The oxygenated form of hemoglobin, Hb 02 carries 02 to the lungs. 

ERYTHROCYTES. Erythrocytes are biconcave diskshaped, blood cells (with pits or depressions in the center on both sides), the primary function of which is to transport hemoglobin, the oxygen-carrying protein. The biconcave shape of the erythrocyte provides a large surface volume ratio and thereby facilitates exchange of oxygen. The average diameter of erythrocytes is 7.5 pm, and thickness at the rim is 2.6 pm and in the center about 0.8 pm. The normal concentration of erythrocytes in blood is approximately 3.9-5.5 million cells per pL in women and 4.1-6 million cells per pL in men. The total life span of erythrocytes in blood is 120 days. 

Carbon monoxide (CO) is generated in incomplete combustion processes. In households the main sources are all kinds of fuel burners (fuel oil, wood, natural gas, coal etc.) and automotive exhaust gas. Carbon monoxide is an odorless and invisible gas, and, due to its affinity to hemoglobin, which is higher than that of oxygen, it reduces the blood s capacity to carry oxygen. Hence it is toxic, especially for unborn and small children as well as for the elderly or people with heart problems or anemia. Even small amounts of CO can be harmful. Tab. 5.6 gives an overview of the relation between CO concentration and the corresponding symptoms of intoxication. 

In addition to energy production, mitochondria play a role in several other cellular activities. For example, mitochondria help regulate the self-destruction of cells (apoptosis). They are also necessary for the production of substances such as cholesterol and heme (a component of hemoglobin, the molecule that carries oxygen in the blood). 

Ultimately, over periods that may be very short, as in the case of volatile substances such as acetone or alcohol, or very long, as with substances such as the dyestuff aniline which latches on to the hemoglobin in the blood that normally carries oxygen, most chemicals will be removed from the body by the body s natural processes. As we have seen, however, there are exceptions, such as lead, that will stay in the bones forever. 

The blood is made up of a liquid portion called the plasma and a solid portion which in turn comprises both red cells and white cells. The red cells, which are formed in the bone marrow and then passed into the blood stream, contain a chemical called hemoglobin that has the capacity to carry oxygen to the body tissues and carbon dioxide away from the body tissues. The white cells are involved in maintaining immunity to infection and in fighting disease. It is the interference by a virus with the immume process of the white cells that give rise to what we know as AIDS (auto immune deficiency syndrome). This condition, however, does not occur from exposure to chemicals. 

A number of chemicals, however, besides lead, which we have already looked at, have the capacity to damage the constituents of the blood and the bone marrow where the blood cells are made. Some act to destroy the red and white cells themselves some act to block the hemoglobin and prevent it from carrying oxygen still others actually change the chemical nature of the hemoglobin, while some act directly to irritate and eventually destroy the bone marrow. A few of the more common are considered below. 

Rudolph AS, Cliff RO, Klipper R, et al. Circulation persistence and biodistribution of lyophilized liposome-encapsulated hemoglobin an oxygen-carrying resuscitative fluid. Crit Care Med 1994 22 142. 

Most proteins have molecnlar masses between 5000 and 500,000. The hormone insnlin, for example, has a molecular mass of about 6000. Hemoglobin, which carries oxygen around in our bloodstream, has a molecular mass near 68,000. ApoB-100, the protein part of the low-density lipoproteins, generally known as the carrier of bad cholesterol, has a molecnlar mass of 513,000. Nucleic acids have molecular masses that range from a few thonsand to many millions. These are clear examples of big molecnles. 

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