Human Haemoglobin And Sickle Cell Disease Biology Essay

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Blood is necessary for every living organism and is the general nutrient fluid, which makes the exchange of matter in the body of every organism. By the heart and blood vessels, blood circulates through tissues and organs of the body and keeps them alive.  One of the major functions of blood is that it carries nutrients to all parts of the body. Wherever blood goes, there is nutrition and consequently life. When the blood supply stops, there is no nutrition and thus no life. Blood also transports oxygen from lungs to tissues and carbon dioxide from the tissues to the lungs. It carries useful substances (hormones, etc) at all parts of the body. Furthermore, it transports useless and harmful substances from the tissues to various organs of elimination such as kidneys (urine), skin (sweat), etc. It also helps the body's defence against microbes and regulates body temperature, because it contributes to the normal distribution of heat in different parts of the body by the movement.

The colour of the blood of mammals, birds, reptiles and fish is red. This is due to a colouring matter, containing haemoglobin. Haemoglobin is used mainly for transporting oxygen. The haemoglobin, when combining with oxygen forms oxyhaemoglobin. It is haemoglobin that gives oxygen to the tissues and then the oxidation (combustion) in the various cells can be completed.  When the blood contains large amounts of oxyhaemoglobin, then colour is bright red (arterial blood). If it contains small amounts of oxyhaemoglobin, then the colour is dark red (venous blood). Another feature of blood is that it is slimy texture. This is consistent with the molecules of the liquid blood plasma. The taste is blood glyph (brackish). This is due to alkaline salts it contains. Furthermore, the specific weight of blood is 1.057 and more specifically it is a bit heavier than an equal volume of water. Through our body a quantity of blood, which is about 6 pounds, is released and it is 7% of all liquid contained in our bodies. It also covers the 1/12 of the whole weight of our body.

The red blood cells are the most numerous cells in peripheral blood. The normal number of them is about 4.5-6 million per micro liter (4.5-6 Ã- 106/ml). Their name is due to their pink-red color pigment hemoglobin which they contain a big quantity of. Haemoglobin is an oxygen carrier protein and is approximately the 90-95% of their weight. Morphologically, as platelets, they differ from all of the other body cells because they have no nucleus. They are produced in the bone marrow and stem directly from the mature erythroblast, which loses the nucleus just before entering the peripheral blood. Normal red blood cells have a disc-shaped shape, but they are thinner in the center, so finally they have a biconcave shape. As a result, on the painted coating a less polished central region is displayed, which is approximately the 1 / 3 of the diameter of the normal erythrocyte. The biconcave shape in combination with the flexibility, which are given by the membrane, allow the red blood cells to pass through the capillaries or slits of the splenic vessels. The red blood cells, because of the haemoglobin they contain, they can transport oxygen from the lungs to the tissues where it is necessary for energy efficiency.

As far as haemoglobin is concerned, the haemoglobin found in red blood cells carries oxygen from the lungs to the tissues and carries carbon dioxide in the reverse route (the "gas exchange"). The normal values for men are 13,5 to 17,5 g/dL (g%) and for women from 11,5 to 15,5 g/dL (g%). When the haemoglobin in someone's blood is reduced it is possible that he suffers from cell anemia. Thus, elevated values may indicate secondary erythrocytosis (rarely true polycythemia). False impaired can be found incomplete mixing of the blood sample with anticoagulant or blood sample from a vein in receiving saline. 

The molecule of haemoglobin (a protein conjugate) is a tetramer composed of 2a and 2b polypeptide chains, each associated with a heme group. The group is a product of heme porphyrin containing divalent iron (Fe 2 +). Haemoglobin (Hb) occurs in different forms based on the amino acid sequence of each subunit. In adults, there are three types of haemoglobin: The HbA1is the 97%, the HbA2 2% and 1% HbF haemoglobin in healthy people. In the newborn HbF is 80%, but this ratio gradually decreases and approximately the eighth month after birth haemoglobin levels reach those of adults. The HbS is an abnormal form of HbA and occurs in people with sickle cell anemia, genetic disorder which produces abnormal haemoglobin HbS (presence of valine instead of glutamic acid). In situations of hypoxia caused precipitation of HbS in erythrocytes become sickle-shaped. The sickled cells are stiff red, have a short shelf life, higher viscosity than normal cells, events that lead to severe anemia.

Sickle cell anemia (also known as sickle cell disease) is a blood disorder that affects the production of haemoglobin (Hb), which is the protein in blood that carries oxygen throughout the body. Sickle cell anemia can pass from parent to child through the genes. Genes carry information on human characteristics such as eye color, hair color and haemoglobin. The haemoglobin found in people that suffer from sickle cell disease is abnormal and gets rough shape. This has resulted in altering the shape of red blood cells, which are the cells that contain haemoglobin. These cells have a normally round shape. In children with sickle cell anemia blood cells have a resembling sickle shape. The abnormal cells live for less time than normal and because of their shape it is difficult for them to pass through small vessels. Sickle cells are often trapped in small blood vessels and trigger intense pain.

Sometimes changes occur in genes, causing this kind of medical disease. Such changes occur in genes, (beta) B-globin in sickle cell anemia, when a person normally inherits two B-globin genes to produce the protein B-globin in haemoglobin. A person can have the sickle cell change (mutation) in one of two genes of B-globin. This person is called sickle cell carrier and is healthy. The carriers may be at risk of having impaired child with sickle cell anemia if the partner is also a sickle cell carrier. When a person has sickle cell change (mutation) in one of the genes of B-globin, and has a particular mutation in another gene of the B-globin may suffer from this disease.

The patients that suffer from sickle cell anemia have mainly anemia, but under certain conditions an aplastic crisis may occur. In this case, the bone marrow stops producing red blood cells, causing the patient strong anemia. It may also show severe chest pain. The pain is the result of entrapment of red blood cells in the lungs. Swelling in hands and feet can also be observed, a symptom that occurs frequently in infants. The pain in any part of the body is possible, but usually in the abdomen and back. The pain is the result of dehydration of the patient or a cold. There is also a possibility that the patient has crises of entrapment. This is because the red cells can be trapped in the spleen of the patient resulting in marked anemia. One stroke is also possible. Children that suffer from sickle cell anemia can have a closed vessel in the brain and a stroke can be caused. In addition, infections can occur. Children with sickle cell anemia can be easily affected by specific bacteria, so whenever a patient has fever or other symptoms should be examined immediately by a doctor.

Unfortunately there is no permanent cure for sickle cell anemia, apart from the bone marrow transplantation, but it is a very risky surgery. There is also some kind of treatment of sickle cell anemia, which is primarily aimed at addressing the acute problems and to remedy or prevent the complications and crises. Transfusions are applicable in both these cases are particularly important in situations of aplastic crisis in spleen entrapment is most common in childhood acute phase. The transfusion may be simple or exchange transfusion as appropriate. Chronic treatment with transfusions, however, can overload the body with iron, where iron chelation therapy in this case is necessary. During the operation applies hydration (saline), administered painkillers to relieve the patient, and given antibiotics in case of infection. As a precaution, penicillin is given for at least the first five years, already from the first two months of life, folic acid. Thus vaccination for hepatitis B, pneumococcal, haemophilus influenza and meningococcal is recommended. As part of the treatment some medicines such as hydroxyurea, erythropoietin, or even a combination of both and often good results can be used.

However prevention is always very important because it can help in preventing this disease. If a couple wants to have children and both parents have the abnormal gene, they should get genetic counseling before deciding to start a family. It can be tested in early pregnancy to determine whether the fetus has sickle cell anemia or not. Thus, if the fetus carries the abnormal gene and has the disease parents are given the opportunity to choose the termination of pregnancy. However, individuals that may have an increased risk of having sickle cell anemia can often have blood tests done to determine whether they have the abnormal gene or not.