Leukocytes are: Function, Formation, Part, Cause, Abnormalities
Leukocytes or better known as white blood cells are blood cells that contain a nucleus. Leukocyte synthesis (leukopoiesis) in the human body is one of the processes of blood cell synthesis or hemopoiesis. The process of hematopoiesis occurs since in the womb, a few weeks after gestation, the yolk sac is the main place for hematopoiesis to occur.
After entering six weeks to 6-7 months in the womb and about two weeks after birth, hematopoiesis occurs in the liver and spleen. Bone marrow is the most important site from 6-7 months of fetal life and is the only source of new blood cells during normal childhood and adulthood.
Definition of Leukocytes
Leukocytes are other cells found in the blood. The general function of leukocytes is very different from that of erythrocytes. Leukocytes function to carry food from the absorption site throughout the body, carry waste materials in the opposite direction and defend the body from harmful foreign objects. The number of leukocytes in the blood is not as much as erythrocytes. Leukocytes are in the amount between 0.1-0.2% of the number of erythrocytes. Leukocytes are not needed all the time by the body.
Also Read: Definition of Leukocytes
These cells are only needed in places where problems with foreign bodies occur. To protect the body from attack by foreign objects in a certain place, leukocytes will be in place of cells that are attacked by foreign objects. If there are enough foreign bodies or their handling requires a certain period of time, some of the leukocytes can reproduce by mitosis outside the bone marrow tissue. (Hoffbrand, 2010)
Normal levels of leukocytes in the blood are less than erythrocytes in a ratio of 1: 700 (Under normal conditions there are 4 × 109 up to 11×109 white blood cells in a liter of healthy adult human blood – about 7000-25000 cells per drop.
In every cubic millimeter of blood there are 6000 to 10000 (an average of 8000) white blood cells. In the case of leukemia, the number can increase to 50000 cells per drop. If the number is more than 11000 cells/mm3 then this condition is called leukocytosis and if the number is less than 4000 cells/mm3, it is called leucopenia. (Hoffbrand, 2010)
Leukocyte function
White blood cells have several functions in the body, namely:
- Defensive function: defends the body against foreign objects, including germs that cause infection.
- Reparative function: repair or prevent damage, especially vascular damage. Leukocytes that play a role are basophils that produce heparin. So that the formation of thrombus vessels - blood vessels can be prevented.
Also Read: Loose connective tissue
Granulocytes and monocytes have an important role in protecting the body against microorganisms. with their ability as phagocytes (phago-eating), they feed on live bacteria that enter the circulatory system. Through the microscope sometimes can be found as many as 10-20 microorganisms ingested by a granulocyte.
When performing this function they are called phagocytes. with the power of its amoeboid movement it can move freely in and out of blood vessels and walk around all parts of the body. in this way he can: (Sadikin, 2011)
Surrounds the area affected by infection or injury, captures living organisms and destroys them, removes other materials such as dirt, debris and others, in the same way, and as granulocytes have enzymes that can break down proteins, which allow damaging living tissue, destroying and throw it away. in this way diseased or injured tissue can be removed and healing possible. (Sadikin, 2011)
As a result of the phagocytic action of white blood cells, inflammation can be completely stopped. If the activity does not work perfectly, it can form pus. Pus contains the “corpses” of friends and foes – phagocytes killed in the process are called pus cells.
Likewise there are many dead germs in the pus and added to the large amount of thawed tissue. and the pus cells will be removed by healthy granulocytes that work as phagocytes. (Sadikin, 2011)
Leukocyte Formation
The formation of white blood cells begins with the early differentiation of pluripotent hemopoietic stem cells into various types of committed stem cells. In addition to these committed cells, to form erythrocytes and form leukocytes. There are two types of leukocytes, namely myelocytic and lymphocytic. The formation of myelocytic leukocytes begins with young cells in the form of myeloblasts, while the formation of lymphocytic leukocytes begins with young cells in the form of lymphoblasts.
Leukocytes formed in the bone marrow, especially granulocytes, are stored in the marrow until they are needed in the circulation. Then, when the need increases, several factors such as cytokines will be released. Under normal circumstances, granulocytes circulating in the whole blood are about three times the number stored in the marrow. This number corresponds to a six-day supply of granulocytes. While most of the lymphocytes will be stored in various lymphoid areas except for a few lymphocytes which are temporarily transported in the blood.
Also Read: Lysosomal Function
The life span of granulocytes after their release from the bone marrow is normally 4-8 hours in circulating blood, and a further 4-5 hours in tissues. In cases of severe tissue infection, the overall life span is often reduced. This is because the granulocytes quickly travel to the infected tissue, perform their functions, and enter into a process in which the cells themselves must be destroyed. Monocytes have a short life span, which is 10-20 hours, in the blood before being in the tissues.
Once inside the tissue, these cells swell to a very large size to become tissue macrophages. In this form, the cells can live for months or even years. These tissue macrophages will be the basis for the tissue macrophage system which is an advanced defense system in the tissue to fight infection.
Lymphocytes continuously enter the circulatory system along with the outflow of lymph from the lymph nodes and other lymphatic tissues. Then, after a few hours, the lymphocytes travel back to the tissues by diapedesis and then re-enter the lymph and return to the lymphoid tissue or to the blood again next. Lymphocytes have a life span of weeks, months, or even years, but this depends on the body's need for these cells.
Leukocyte Parts
Leukocytes or white blood cells are produced by the bone marrow. Leukocytes or white blood cells that have been produced have a short life of only 1 to 3 days. Leukocytes or white blood cells are divided into:
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monocytes
Is a component of leukocytes or white blood cells whose job is to break down and fight the germs of disease that exist in the body.
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Lymphocytes
Is a component of leukocytes or white blood cells whose job is to form antibodies to the body.
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Neutrophils
Is a component of leukocytes or white blood cells whose function is to form the first level of resistance in various types of infections.
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Basophils
Is a component of leukocytes or white blood cells whose job is to give a signal when there is an infection that attacks.
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Eosinophils
Is a component of laukocytes or white blood cells whose job is to fight all bacteria that are lodged in the body.
Also Read: Big and Small Circulatory System
Causes of High Leukocytes
The normal number of leukocytes or white blood cells is around 4,500 to 10,000 cells per microliter. When a person's body has a leukocyte or white blood cell count that is too high, it can means leukocytes or white blood cells or you are sick because of leukocytes or white blood cells alone. Many things can be the cause of high leukocytes including:
- The production of leukocytes or white blood cells is higher than usual because leukocytes or white blood cells work against infections in the body.
- Leukocytes or white blood cells become more in number because they react to certain types of drugs.
- Leukocytes or white blood cells become higher in number because there is a problem with the bone marrow so that the production of leukocytes or white blood cells increases.
- High leukocytes or white blood cells due to boosting the immune system.
- The cause of excess leukocytes or white blood cells because the body is under stress.
- Leukocytes or high white blood cells because a person is taking drugs that contain inflammation.
- Leukocytes or high white blood cells caused by consuming excessive cigarettes that have been done for several years.
Apart from the causes above, leukocytes or white blood cells can increase in number due to: a person is suffering from a disease caused by leukocytes or white blood cells themselves. example :
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Leukemia
Is a type of cancer that attacks the spinal cord, so it can affect the production process of lymphocytes and meiloid.
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Myelofibrosis
Is a disorder suffered by the spinal cord that can cause the body to produce leukocytes or white blood cells in more quantities than usual.
Abnormalities that occur in leukocytes
- SHIFT TO THE LEFT (Shift To The Left), An increase in the number of young leukocytes in the peripheral blood. For example, an increase in the number of rod neutrophils > 10% in the peripheral blood.
- NEUTROPHILIA, An increase in the number of neutrophils in the peripheral blood is more than normal, this can be caused by:
- Acute infections e.g. pneumonia, pneumonia, meningitis
- Local infection accompanied by the production and accumulation of pus
- Intoxication, eg to chemicals, uremia.
- In addition there is also Physiological Neutrophilia caused by excessive exercise, stress, this is also called Pseudonetrophylia.
- Eosinophilia, An increase in the number of eosinophils in the peripheral blood, is found in:
- Allergic diseases (Urticaria, Asthma bronchiale).
- Parasitic infections (eg: Schistosomiasis, Trichinosis, Hookworm)
- After irradiation
- Hodgkin's disease, Poly arthritis nodosa, etc
- Malignancy, skin diseases such as Eczema
- BASOPHILIA, An increase in the number of basophils in the blood, is found in:
- Infection by viruses (Smallpox, Chickenpox)
- Sometimes after splenectomy, chronic hemolytic anemia
Also Read: Blood plasma
- MONOCYTOSIS, An increase in the number of monocytes in the blood, is found in:
- Bacillary infection (TB, subacute endocarditis)
- Protozoan infections (Malaria, chronic amoebic dysentery)
- Hodgkin's disease, Rheumatoid arthritis
- LYMPOSYTOSIS, An increase in the number of lymphocytes in the blood, is found in:
- Acute infections (Pertussis, hepatitis, infectious mononucleosis) and chronic infections
- In infants (infants and children)
- Chronic inflammation eg Ulcerative Colitis Kol
- Metabolic disorders (hyperthyroidism)
- NEUTROPENIA, Decrease in the number of neutrophils in the peripheral blood, causes:
- Infectious disease
- Typhoid fever, Hepatitis, Influenza, measles, malaria, as well as every type of acute infection.
- Chemicals and physics for example in radiation and drugs, Hyperspleenism, liver disease.
- LYMPHOPENIA, Decrease in the number of lymphocytes in the peripheral blood, causes:
- Corticosteroid death for example due to therapy with steroid drugs.
- Severe disease eg: heart failure, kidney failure, severe tuberculosis.
- AGRANULOCYTOSIS, The sudden disappearance of granulocytes in the peripheral blood in a previously normal person. In common agranulocytosis, the leukocyte count is low and mature lymphocytes are the only type of leukocyte present in the peripheral blood. Cause: Autoimmune disease, also drugs examples of drugs: Antalgin and sulfonamides.
- LEUKEMOID REACTION, Reactive leukocytosis that is not a malignant process (benign) with immature and mature leukocytes entering the circulation in excessive numbers.
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