Albumin is one of the three main components of plasma. The other two proteins are globulins and fibrinogen. All three proteins are manufactured by the liver. These three proteins circulate in plasma and act as carriers for small molecules. Albumin, the most plentiful, is similar in texture to egg whites and gives blood its gummy texture. It is soluble in water and coagulable by heat. The globulins, three in number: alpha, beta, and gamma. They are divided on the basis of electrophoretic mobility. The globulins transport certain proteins. They number half the albumin proteins found in plasma. The globulin proteins are insoluble in water, soluble in saline solutions, and coagulable by heat. Globulins are also found in cerebrospinal fluid. Gamma globulins are the antibodies of the blood, giving immunity to disease. Only 3% of plasma is made up of fibrinogen. It is an important link in the chain of reactions that leads to blood clotting (coagulation). It uses the enzyme thrombin to form a web of fine protein fibres, called fibrin, that bindblood cells together, creating a bridge over which injured tissue can rebuild itself while blood continues to flow underneath. As an important factor to coagulation, it is often referred to as factorI. Research Albumin
Blood is one of the three main fluids in the body (the other two are the fluid around cells and the fluid inside the cells). It supplies oxygen, transports nutrients, waste, and hormonal messengers to each of the sixty billion cells in the body, as well as defending the body against foreign material. There are close to 30 trillion blood cells in an adult. Each cubic millimeter of blood contains from 4 1/2 to 5 1/2 million red blood cells and an average total of 7,500 white blood cells.
Blood has four main components: red blood cells, white blood cells, platelets, and liquid plasma. Since both red and white blood cells are continually being destroyed, the body must continue to produce new ones. About 2 1/2 million red blood cells die every second, at the same time, about 2 1/ 2 million new ones are created. Research Blood
Normal red blood cells are of four main groups in relation to their behaviour when mixed with bloodplasma (or serum) of another individual. Similarly the plasma (and serum) of each individual belongs to one of four groups. If cells of one group meet plasma of an 'incompatible' group, the cells stick together in blocks. These clumps obstruct blood vessels and may cause death. The interaction of the incompatible cells and plasma is called 'agglutination'. The provocative substance in the cells is called the agglutlnogen, while the defensive substance in the plasma is the agglutinin. A similar mechanism develops in relation to our immunity to infections by certain bacteria and viruses. In blood transfusion, the amount of plasma administered is small in relation to the large amount of plasma in the recipient's circulation. On the other hand, even a small quantity of cells given to a patient whose plasma will not tolerate that particular type of cell, will lead to clumping of the donor's cells in the recipient's blood vessels. The importance therefore lies in the cells of the donor and the plasma of the recipient.l Plasma and serum for this purpose are identical and the serum obtained when a small quantity of blood is allowed to clot is used for testing against the donor's red cells. In order to determine a patient's blood group, a small quantity of blood is obtained from a finger or ear prick and immediately mixed with citrate to prevent clotting; the cells are then tested against special serum of known groups. To obtain the patient's serum for cross-matching, 5 ml of blood is taken, by vein puncture, and allowed to clot.
The four common groups have been numbered variously. The Moss classification I, II, III, and IV was used extensively until the adoption of the International A, B, O classification, which describes the groups according to the presence or absence of the specific cell factors, which are of two types, A and B. Thus we have four blood groups in the international system. In the first of these, both cell factors are present but no serum factors. The serum factors are called anti-A and anti-B, and obviously the cellfactor A and the serum factor anti-A could not exist in the same person. The second group contains cellfactor A and serum factor anti-B. The third group contains cellfactor B with serum factor anti-A, and the fourth group contains neither cellfactor but both serum factors. The fourth group could therefore be given to any of the other groups and the cells, having no clumping factors, would be tolerated in any recipient. On the other hand, the first group with both cell factors could not be given to any other group. The terms universal donor, Group O (MossIV), and universal recipient, Group AB (MossI), were used to amplify the earlier grouping system. Transfusion with the wrong group of blood is usually fatal so that very great care has to be taken in the determination of the blood group, both of donor and recipient.
Since the 1950s hitherto unexplained incompatability was found to be due to the presence of other factors than the A, B, O, agglutinogens. The most important of these is the rhesus cellfactor. Certain monkeys (Rhesus species) have this factor naturally, but it is present in only 85 per cent of white people in England and America. The other 15 per cent - Rh negative - may become sensitized to Rh positive cells by repeated transfusion of Rh positive blood. A rhesus negative mother whose husband is ph positive may produce an Rh positive baby. A battle occurs between the unborn baby's cells and the mother's plasma. The baby may die before birth (miscarriage) or be born with very severe anaemia and jaundice. If born alive, the baby is treated by complete replacement of its blood to get rid of the mother' s sensitized Rh negative plasma. This is 'exsanguination-transfusion'. During the 1950s blood grouping in preparation for transfusion became a complex and very responsible task. In most hospitals it is undertaken by specialists - perhaps a pathologist or transfusion officer. During the 1980s as HIV paranoia spread, even more testing started to be done. Research Blood Groups
The transfer of blood from one individual to another first became a practical proposition during the Great War. The recognition of four major blood groups indicated that there were limitations on blood transfusion which necessitated very careful examination of the blood of the two individuals concerned. In the early days of transfusion after preliminary grouping, the blood was transferred from the donor to the recipient by the ' direct' method, using a two-way tap and syringe, so that the blood was not exposed to the air and had no opportunity for clotting. The 'indirect' method was later introduced in which the donor's blood was received into a solution of sodium citrate which prevented it from clotting by inactivating the calcium. Within an hour or so the blood was then injected into the veins of the recipient. Prior to the second World War, most large hospital centres in Great Britain maintained a panel of blood donors who were willing to come to the hospital at any hour of the day or night for emergency transfusion. The relatives of patients also were called upon, if with the right blood group, to give their blood.
The necessities of war, and the greater demands of surgery for blood transfusion led to the establishment of ' blood banks', in which are stored large quantities of blood taken at a convenient time from thousands of volunteers. With suitable refrigeration, blood may be stored for three weeks with safety and such blood is quite suitable for the treatment of shock and conditions of blood loss. Certain other disorders, mainly medical conditions affecting the formation of red cells in the bonemarrow, are preferably treated with the transfusion of fresh blood: this seems to possess properties which become lost in storage. Blood transfusion performs a double purpose. It replaces the oxygen-carrying red cells and its fluidfraction, the plasma, contributes protein which maintains the circulating blood volume, thus preventing the escape of water into the tissues. Plasma or serum may be separated from the whole blood and dried. In this form it was used extensively during the Second World War because it could be stored indefinitely and could be reconstituted by the addition of distilled water when infusion was needed in the treatment of shock. By the extraction of the fluid portion of the whole blood, the cell content may be concentrated. Such a preparation is known as packed cells. This has become of particular value if it is necessary to raise the haemoglobin rapidly without raising the blood volume unduly. Such a procedure may be required in the treatment of severe anaemia arising from toxaemia. Research Blood Transfusion
The endoplasmic reticulum (cytoskeleton) forms a network of membranous tubes and flattened sacs within a cell and is distributed throughout the cell, predominantly between the plasmamembrane and the membrane that encircles the nucleus. Endoplasmic reticulum networks may be loosely organized of tightly packed. The membranes that form the interrelated channels may appear smooth, while others appear rough. The rough-surfaced membranes are dotted with ribosomes that form granules on the outer surfaces and are the site of proteinsynthesis. The ribosomes on the rough surface deposit the newly formed proteins into the lumen, or inner space, of the
endoplasmic reticulum. The
endoplasmic reticulum segregates the proteins into those that will be needed in the cytoplasm and those that will be transported to the other organelles or secreted from the cell. The smooth
endoplasmic reticulum has no ribosomes and is, instead, a site of lipidsynthesis. The endoplasmic reticulum appears to serve several functions. Its membranes provide an increase in surface area where chemical reactions can occur. The channels of the reticulum provide both storage space for products synthesized by the cell and transportation routes through which material can travel through other parts of the cell. The endoplasmic reticulum is also the cell's membranefactory. Phospholipids and cholesterol, the main components of membranes throughout the cell, are synthesized in the smooth portion of the endoplasmic reticulum. These compounds form the coating of protein filled sacs, called vesicles, that break off from the endoplasmic reticulum, migrate to another organelle, fuse with it, and then deposit the protein cargo. Most of the proteins leaving the
endoplasmic reticulum are still not mature and undergo further processing in another organelle, the Golgi apparatus, before they are ready to perform their functions within or outside the cell. Research Endoplasmic Reticulum
Erythrocytes or red blood cells, carry 99% of the oxygen the body needs. Although plasma circulates throughout the body, it can only carry about one percent of the oxygen that the body needs. Red blood cells are the most abundant cells in the body, constituting about 45% of the blood. Their main function is to carry oxygen to tissue and remove carbon dioxide waste. Red blood cells are mainly made of water and hemoglobin, an iron- containing protein. Hemoglobin gives red blood cells their colour and is so highly concentrated in individual cells that it almost forms crystals. It is an important protein in the transport of oxygen and carbon dioxide. Red blood cells are manufactured in myeloid tissue, better known as red bonemarrow. It is found mainly in the sternum, ribs, and cranial bones, although a few other bones also contain small amounts of the tissue. Each cell is very small, about .008 centimeter in diameter and shaped like a round cushion, with a hollow on each side. The rate of red cellformation is regulated by a messenger hormone called erythropoietin which is
produced in the kidneys. This hormone signals the cell to begin growth. First, the cell splits in two. Each of the pair in turn divides until there are sixteen red blood cells. Inside each of the cells hemoglobin is being produced. This production continues until the concentration of the protein becomes 95% of the dry weight of the cell. As this saturation point nears, the cell expels its nucleus, taking on a biconcave shape and thus, increasing its oxygen- carrying potential. At this point, the cell is called a corpuscle. The production of a corpuscle takes six days to complete. Yet the cell will only live for 120 days. About two and a half million red blood cells are destroyed every second. They are broken down into their constituent parts, some of which can be used again to manufacture new red cells. Normal red bloodcell production depends upon the body having an adequate supply of iron and two main vitamins: B12 and folic acid. There are many diseases due to deficiencies in red cells, they are collectively known as anemia. Hemolytic anemia is caused by
excessive destruction of red blood cells. It is often caused by poisoning, or a disease such as malaria, or may be an inherited condition. Pernicious anemia, in which large numbers of abnormally large red cells are made, is due to lack of proper absorption of vitamin B12. It can now be easily controlled with regular injections of the vitamin. Research Erythrocytes
Fibrinogen is one of the three main components of plasma. The other two being globulins and albumin. Only 3% of plasma is made up of fibrinogen. It is an important link in the chain of reactions that leads to blood clotting. It uses the enzyme thrombin to form a web of fine protein fibres, called fibrin, that bindblood cells together, creating a bridge over which injured tissue can rebuild itself while blood continues to flow underneath. As an important factor to coagulation, it is often referred to as factorI. Research Fibrinogen
Gamma globulin is a mixture of proteins in plasma, the fluid portion of blood. It contains antibodies produced in the liver, spleen, bonemarrow, and lymphatic glands to protect the body from invading viruses or bacteria. Each disease antigen stimulates production of a specific antibody, which circulates in the blood for a period of time. Since the gamma globulin contains these antibodies, it is sometimes taken from patients who have recovered from chickenpox, hepatitis, and other infectious diseases and given to confer a rapid but short- term immunity on persons recently exposed to those diseases.
Persons who suffer from an unusual deficiency of gamma globulin known as agammaglobulinemia are deficient in antibodies and may require periodic infusions of gamma globulin to maintain protection. In 1969 scientists in England and at Rockefeller University determined the chemical structure of gamma globulin, an important advance in the knowledge of immunity. Research Gamma Globulin
Haemofiltration is a temporary treatment for patients in acute (usually temporary) kidney failure. Large volumes of plasma water are filtered out of the bloodstream, to be replaced by a sterile electrolyte solution. This has the effect of removing waste products, regulating the plasma electrolytes and getting rid of excess water. For critically ill patients it is safer than dialysis. Research Haemofiltration
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Albumin
