Cancer is the common term for aggressive and usually fatal forms of a large class of diseases known as neoplasms. A neoplasm is described as being relatively autonomous because it does not fully obey the biological mechanisms that govern the growth and metabolism of individual cells and the overall cell interactions of the living organism. Some neoplasm grow more rapidly than the tissues from which they arise; others grow at a normal pace but because of other factors eventually become recognizable as abnormal growths. The changes seen in a neoplasm are heritable in that these characteristics are passed on from each cell to its progeny, or daughter cells.
Classification of neoplasm as either benign or malignant relates to their behavior. A benign neoplasm, for instance, is encapsulated; malignant neoplasms are not. Malignancies grow more rapidly than do benign forms and invade adjacent, normal tissue. Tissue of a benign tumor is structured similarly to the tissue from which it is derived; malignant tissue has an abnormal and unstructured appearance. Most malignant tumors, in fact, show abnormalities in chromosome structure, that is, the structure of the DNA molecules that constitute the genetic materials duplicated and passed on the later generations of cells. Most important, benign neoplasm do not metastasize, that is, begin to grow at sites other than the point of origin, whereas malignant tumors do. The term cancer always denotes a malignant neoplasm, whereas the term of Tumor indicates a readily defined mass of tissue distinguishable from normal living tissue.
Tuesday, May 27, 2008
Skin Cancer
Skin cancer is the most common form of cancer in the United States and generally tropical such as in Indonesia, Brazil and African country. In United States more than 600,000 cases diagnosed annually. The most common types of skin cancer are the highly curable basal-cell or squamous-cell cancers. The most serious skin cancer is melanoma, which causes more than 6,000 deaths each year. Factors that increase the risk of developing skin cancer include excessive expose to the Sun's ultraviolet rays, a fair complexion, or occupational exposure to coal tar, pitch or radium.
A change in a mole or other spot on the skin may be the first sign of an early malignant melanoma or other form of skin cancer. Regular self-examination to detect changes in asymmetry, border, color, and diameter of a mole is the best way to detect a problem while it is still treatable.
A common benign mole is usually round and symmetrical, with smooth, even borders (top left). A persistence reddish patch or irritated area on the arms, legs, or shoulders may be a sign of basal-cell carcinoma (top right). Some forms of early malignant melanoma have an asymmetrical shape (bottom left) or an uneven border with notched or scalloped edges (bottom right).
The form of skin cancer that is sometimes to be avoided is warts or a nibble, abnormal moles and abnormal pimple or acne. If you have this abnormal sign on your skin you must check this condition to the doctor to make sure that those conditions are not including to dangerous cancer.
A change in a mole or other spot on the skin may be the first sign of an early malignant melanoma or other form of skin cancer. Regular self-examination to detect changes in asymmetry, border, color, and diameter of a mole is the best way to detect a problem while it is still treatable.
A common benign mole is usually round and symmetrical, with smooth, even borders (top left). A persistence reddish patch or irritated area on the arms, legs, or shoulders may be a sign of basal-cell carcinoma (top right). Some forms of early malignant melanoma have an asymmetrical shape (bottom left) or an uneven border with notched or scalloped edges (bottom right).
The form of skin cancer that is sometimes to be avoided is warts or a nibble, abnormal moles and abnormal pimple or acne. If you have this abnormal sign on your skin you must check this condition to the doctor to make sure that those conditions are not including to dangerous cancer.
Sunday, May 25, 2008
Cancer
In modern society cancer is the disease most feared by the majority of people throughout the world, supplanting the "white death" or tuberculosis, of the last century; the "back death," or bubonic plague, of the middle Ages; and the leprosy of biblical times. Cancer has been known and described throughout history, although its greater prevalence today is undoubtedly due to the conquest by medical science of most infectious diseases and to the increased life span of humans.
The study of cancer is known as the field of oncology. In the early 1990s nearly 6 million new cancer cases and more than 4 million deaths from cancer were being reported worldwide each year. The leading fatal cancer in the world is lung cancer, which has risen rapidly because of the spread of cigarette smoking in developing countries. Stomach cancer, prevalent in Asia, is the second most fatal form of cancer in men, after lung cancer. Also on the increase is the leading killer of women, breast cancer. The fourth on the list is colon or rectum cancer, a disease that mainly strikes the elderly. In the United States in the early 1990s more than one-fifth of all deaths were caused by cancer; only cardiovascular diseases accounted for a higher percentage.
In 1993 the American Cancer Society predicted that about 33 percent of Americans will eventually develop some form of the disease. Skin cancer is the most prevalent cancer in both men and women, followed by prostate cancer in men and breast cancer in women. Lung cancer, however, causes the most deaths in both men and women. Leukemia, cancer of the blood, is the most common type seen in children. An increasing incidence of cancer has been observed over the past few decades, due to improved cancer screening programs, to the increasing age of the population, and also to the large number of tobacco smokers, particularly women. In 1990 care and treatment of cancer patients in the United States cost more than $40 billion annually. The U.S. government was spending at least $2 billion each year for cancer research by the mild 1990s. Because of the marked improvement in the types of drugs available cancer patients under 30 years of age is decreasing, even though the number of deaths from cancer is increasing in the population as a whole.
The study of cancer is known as the field of oncology. In the early 1990s nearly 6 million new cancer cases and more than 4 million deaths from cancer were being reported worldwide each year. The leading fatal cancer in the world is lung cancer, which has risen rapidly because of the spread of cigarette smoking in developing countries. Stomach cancer, prevalent in Asia, is the second most fatal form of cancer in men, after lung cancer. Also on the increase is the leading killer of women, breast cancer. The fourth on the list is colon or rectum cancer, a disease that mainly strikes the elderly. In the United States in the early 1990s more than one-fifth of all deaths were caused by cancer; only cardiovascular diseases accounted for a higher percentage.
In 1993 the American Cancer Society predicted that about 33 percent of Americans will eventually develop some form of the disease. Skin cancer is the most prevalent cancer in both men and women, followed by prostate cancer in men and breast cancer in women. Lung cancer, however, causes the most deaths in both men and women. Leukemia, cancer of the blood, is the most common type seen in children. An increasing incidence of cancer has been observed over the past few decades, due to improved cancer screening programs, to the increasing age of the population, and also to the large number of tobacco smokers, particularly women. In 1990 care and treatment of cancer patients in the United States cost more than $40 billion annually. The U.S. government was spending at least $2 billion each year for cancer research by the mild 1990s. Because of the marked improvement in the types of drugs available cancer patients under 30 years of age is decreasing, even though the number of deaths from cancer is increasing in the population as a whole.
Monday, May 19, 2008
Blood Clotting
The clotting process is initiated by a protein called tissue factor, which is bound to the membranes of most cells outside the bloodstream. Blood coming into contact with these membranes sets off a sequence of reactions involving various blood protein called factors. Thus, a molecule of factor VII coming into contact with tissue factor converts to an active form that in turn converts ten molecules of factor X into thromboplastin, with the help of calcium ions. Thromboplastin in turn binds to factor Va, which then binds to the protein prothrombin to form two million molecules of the clotting enzyme thrombin. Thrombin acts as a catalyst to convert fibrinogen to billions of molecules of the insoluble protein fibrin, the basis of the final clot. The clot is made firm by factor XIII, reinforced by blood platelets.
Because minor injuries often occur, the clotting process is almost constantly taking place somewhere in the body. It must be terminated quickly, however, or blood would clot everywhere and death would ensue. To prevent this form happening, plasma proteins known as fibrinol-ysins, or plasmin, dissolve old clots in the bloodstream.
Blood Transfusions
Transfusions involve the intravenous administration of blood from a donor to a patient. The procedure's safety and effectiveness relates, in large measure, to careful donor selection and to pre-transfusion testing. Blood is now mainly transfused as components rather than as whole blood; a donated unit is separated into its cellular and plasma constituents and transfused according to the patient's clinical needs. Thus, blood from single donor can provide or the needs of several patients.
There is no true artificial substitute for blood. Some experimental solutions can transport oxygen to the tissues temporarily, and synthetic plasma substitutes are used to raise blood fluid levels.
Thursday, May 15, 2008
Blood Diseases
Anemia
Anemia is a deficiency of hemoglobin in the blood, generally caused by blood loss; abnormal destruction of the red cells, as in Sickle-cell disease; or inadequate red cells formation by the bone marrow, as in a plasmatic anemia and pernicious anemia. Anemia also occurs as a result of methermoglobinemia, a disorder in which methemoglobin, a nonfunctional form of hemoglobin, is present in the red cells.
In some persons, the concentration of red cells and of hemoglobin in the blood may be abnormally increased, rather than decreased, resulting in polycythemia. This is usually caused by an increased production of red cells, but in some persons it may be caused by a decreased volume of plasma.
Neutropenia
Deficiency of circulating granulocytes with poor resistance to infection, may occur in many diseases. One common cause is the use of X rays and toxic drugs to treat many malignant diseases.
Leukemia
A great increase in abnormal leukecytes may occur for unknown reasons, resulting in the diseases known as the leukemias. These range from the chronic lymphocytic leukemia, in which a person may live form many years, to devastating acute leukemia, often causing death within month.
Thrombocytopenia
The number of platelets can severely decrease, with danger of bleeding. Perhaps the most common cause of platelet deficiency, or thrombocytopenia, is an autoimmune disease related to autoimmune hemolytic anemia. The difference is that, in these cases, the body produces antibodies that attack only the platelets.
Hemophilia
Deficiencies of one or more of the plasma coagulation factors may also cause abnormal bleeding. The existence of many of the clothing factors was recognized only when persons were found who lacked such a factor. The best known such bleeding disorder is Hemophilia.
Thromboembolic Diseases
Abnormal clotting in the blood vessels, known as thromboembolic disease, may be caused by an excess of one or more of the plasma clothing factors, or at times to a deficiency of one of the fibrinolytic factors. This group of disorders is one of the most common causes of death in middle aged and elderly persons.
Anemia is a deficiency of hemoglobin in the blood, generally caused by blood loss; abnormal destruction of the red cells, as in Sickle-cell disease; or inadequate red cells formation by the bone marrow, as in a plasmatic anemia and pernicious anemia. Anemia also occurs as a result of methermoglobinemia, a disorder in which methemoglobin, a nonfunctional form of hemoglobin, is present in the red cells.
In some persons, the concentration of red cells and of hemoglobin in the blood may be abnormally increased, rather than decreased, resulting in polycythemia. This is usually caused by an increased production of red cells, but in some persons it may be caused by a decreased volume of plasma.
Neutropenia
Deficiency of circulating granulocytes with poor resistance to infection, may occur in many diseases. One common cause is the use of X rays and toxic drugs to treat many malignant diseases.
Leukemia
A great increase in abnormal leukecytes may occur for unknown reasons, resulting in the diseases known as the leukemias. These range from the chronic lymphocytic leukemia, in which a person may live form many years, to devastating acute leukemia, often causing death within month.
Thrombocytopenia
The number of platelets can severely decrease, with danger of bleeding. Perhaps the most common cause of platelet deficiency, or thrombocytopenia, is an autoimmune disease related to autoimmune hemolytic anemia. The difference is that, in these cases, the body produces antibodies that attack only the platelets.
Hemophilia
Deficiencies of one or more of the plasma coagulation factors may also cause abnormal bleeding. The existence of many of the clothing factors was recognized only when persons were found who lacked such a factor. The best known such bleeding disorder is Hemophilia.
Thromboembolic Diseases
Abnormal clotting in the blood vessels, known as thromboembolic disease, may be caused by an excess of one or more of the plasma clothing factors, or at times to a deficiency of one of the fibrinolytic factors. This group of disorders is one of the most common causes of death in middle aged and elderly persons.
Tuesday, May 13, 2008
White Blood Cells
White blood cells, or leukocytes, detent the body against foreign organisms. They are almost colorless, are considerably larger than red cells, have a nucleus, and are much less numerous; only one or two exist for every 1,000 red cells. The number increases in the presence of infection.
There are three types; granulocytes, lymphocytes, and monocytes. Granulocytes, accounting for about 70 percent of all white cells, include neutrophilis, ensinophils, and basophils. They are formed in the bone marrow. Lymphocytes form primarily in the Speen and lymphnodes. Monocytes are believed to originate from lymphocytes.
Platelets
Platelets, or thrombocytes, are tiny bits of cytoplasm, much smaller than the red blood cells but lacking a nucleus. They are round or biconcave disks and are normally about 30 to 40 times more numerous than the white blood cells. They are produced as broken fragments of the megakaryocytes. The plateletss' primary function is in the clotting process described below.
Plasma
Plasma is a complex, colorless solution, about 90 percent water, that carries different ions and molecules, including protein, enzymes, hormones, nutrients, waste materials such as urea, and fibrinogen, the protein that aids in clotting. The most abundant plasma protein is albumin, which normally keeps a large portion of the body water in the blood. When the plasma albumin concentration becomes dangerously low, because of disease, free water collects in the tissues outside the blood vessels, producing swelling called edema.
Globulin are large protein molecules of many chemical structures and functions. The antibodies, produced by lymphocytes, are globulin and are carried throughout the body, where many of them fight bacterial or viral invasion. Other antibodies are related to the blood groups.
An important function of plasma is to transport nutrients to the tissue. Glucose, absorb from the bowels, constitutes a major source of body energy. Some plasma proteins and fats are also used by the tissue for cell growth and energy. Minerals essential to body function, although present only in trace amounts, are important elements of the plasma.
There are three types; granulocytes, lymphocytes, and monocytes. Granulocytes, accounting for about 70 percent of all white cells, include neutrophilis, ensinophils, and basophils. They are formed in the bone marrow. Lymphocytes form primarily in the Speen and lymphnodes. Monocytes are believed to originate from lymphocytes.
Platelets
Platelets, or thrombocytes, are tiny bits of cytoplasm, much smaller than the red blood cells but lacking a nucleus. They are round or biconcave disks and are normally about 30 to 40 times more numerous than the white blood cells. They are produced as broken fragments of the megakaryocytes. The plateletss' primary function is in the clotting process described below.
Plasma
Plasma is a complex, colorless solution, about 90 percent water, that carries different ions and molecules, including protein, enzymes, hormones, nutrients, waste materials such as urea, and fibrinogen, the protein that aids in clotting. The most abundant plasma protein is albumin, which normally keeps a large portion of the body water in the blood. When the plasma albumin concentration becomes dangerously low, because of disease, free water collects in the tissues outside the blood vessels, producing swelling called edema.
Globulin are large protein molecules of many chemical structures and functions. The antibodies, produced by lymphocytes, are globulin and are carried throughout the body, where many of them fight bacterial or viral invasion. Other antibodies are related to the blood groups.
An important function of plasma is to transport nutrients to the tissue. Glucose, absorb from the bowels, constitutes a major source of body energy. Some plasma proteins and fats are also used by the tissue for cell growth and energy. Minerals essential to body function, although present only in trace amounts, are important elements of the plasma.
Sunday, May 11, 2008
Blood and the Type
Blood is the essential red fluid that is pumped by the heart trough the circulatory system of humans and all higher animals. It is complex in its composition and its functions. Blood has two main constituents. The cells, or corpuscles, comprise about 45 percent, and the liquid portion, or plasma, in which the cells are suspended comprises 55 percent. The blood cells comprise three main types, each with specific functions; red blood cells, white blood cells and platelets.
Red Blood Cells
Red blood cells, or erythrocytes, are tiny, round, biconcave disks averaging7.5 microns (0.003 in) in diameter. A normal 76.5 kg (170-lb) main has about 5 l (5.3 qt) of blood, containing more than 25 trillion red cells. Because the normal life span of red cells is only about 120 days, more than 200 billion cells are normally destroyed each day by the spleen and must be replaced. Red cells are made in the bone marrow.
The main function of the red blood cells is to transport oxygen from the lungs to the tissue. Oxidations of various food substances to supply most of the energy requirements of the body results in carbon dioxide, one of the chief waste products, and red blood cells carry it to the lungs for release and to pick up more oxygen.
The substance in the red blood cells that is largely responsible for their ability to carry oxygen and carbon dioxide is hemoglobin, the material that gives the cells their red color. Produced in the bone marrow and broken down in the spleen, it is a protein complex comprising many linked amino acids, and occupies almost the entire volume of a red blood cell. Essential to its structure and function is iron.
Blood Typing
The cell wall contains many antigenic proteins, which determine the blood type. Among these proteins are the antigens. A and B, the major blood group factors. Blood with antigen B is group B. Blood with both antigens is called AB, and blood with neither is called group O. Normally, the plasma of every person contains an antibody against the A or B antigens in the red cells are determined by mixing the cells with known typing serums. The antibodies in the serum or plasma are determined by mixing it with cells of known A or B type. Such typing is necessary in preparation for blood transfusion. Antigens of the various Rh and Hr types, M and N, S and Kell, Duffy, and many others also exist in the red blood cell. All like the A and B antigens, are inherited. When the red cell antigens are determined, they show so many different combinations as to make a persons blood type almost as individual as a fingerprint.
Antibodies against antigens other than A and B do not normally occurs in the plasma. They may appear after transfusion, however, and may cause transfusion reactions and destruction of red blood cells or hemolytic disease of the newborn.
Red Blood Cells
Red blood cells, or erythrocytes, are tiny, round, biconcave disks averaging7.5 microns (0.003 in) in diameter. A normal 76.5 kg (170-lb) main has about 5 l (5.3 qt) of blood, containing more than 25 trillion red cells. Because the normal life span of red cells is only about 120 days, more than 200 billion cells are normally destroyed each day by the spleen and must be replaced. Red cells are made in the bone marrow.
The main function of the red blood cells is to transport oxygen from the lungs to the tissue. Oxidations of various food substances to supply most of the energy requirements of the body results in carbon dioxide, one of the chief waste products, and red blood cells carry it to the lungs for release and to pick up more oxygen.
The substance in the red blood cells that is largely responsible for their ability to carry oxygen and carbon dioxide is hemoglobin, the material that gives the cells their red color. Produced in the bone marrow and broken down in the spleen, it is a protein complex comprising many linked amino acids, and occupies almost the entire volume of a red blood cell. Essential to its structure and function is iron.
Blood Typing
The cell wall contains many antigenic proteins, which determine the blood type. Among these proteins are the antigens. A and B, the major blood group factors. Blood with antigen B is group B. Blood with both antigens is called AB, and blood with neither is called group O. Normally, the plasma of every person contains an antibody against the A or B antigens in the red cells are determined by mixing the cells with known typing serums. The antibodies in the serum or plasma are determined by mixing it with cells of known A or B type. Such typing is necessary in preparation for blood transfusion. Antigens of the various Rh and Hr types, M and N, S and Kell, Duffy, and many others also exist in the red blood cell. All like the A and B antigens, are inherited. When the red cell antigens are determined, they show so many different combinations as to make a persons blood type almost as individual as a fingerprint.
Antibodies against antigens other than A and B do not normally occurs in the plasma. They may appear after transfusion, however, and may cause transfusion reactions and destruction of red blood cells or hemolytic disease of the newborn.
Thursday, May 1, 2008
Skin Diseases
The skin is subject to many disorders. They occur through the direct action of external agents or as symptoms of disease in other parts of the body. Susceptibility to skin disorders is modified and sometimes determinate by generic factors.
Lesions
The appearance of abnormal changes, or lesions, in the skin is an important element in diagnosis and treatment. Various lesions can occur, not all of them diseases related. A flat lesion of a color differing from surrounding skin is called a Freckle. A papule is a solid, elevated by superficial mass, such as a raised Mole or a Wart. A wheal is a transitory lesion resulting from an allergic response, such as to an insect bite. A nodule is a solid mass that extends deeper, such as in certain tumors and cysts. A vesicle is a tiny blister filled with clear fluid, such as in early chicken pox. A bulla is a large blister, most often seen as the result of a coloration caused by deposits of blood or blood pigments within the skin.
The appearance of such lesions may be modified by secondary changes. These include scales or flakes of dead skin, as seen in Psoriasis and Dandruff; crusts, typically dried masses of material that have oozed out as in impetigo; fissures, or sharp breaks, as seen in athlete's foot; Ulcers, or destruction of one or more skin layers, exposing underlying tissue replacing lost tissue; and lichenification, a thickened scaly area in which normal skin creases and lines are exaggerated. Lesions may be seen in several different lesions.
Malignant Tumors
Any metastasizing tumor from else where in the body may appear in the skin. Many malignant tumors also originate in the skin. Four should be mentioned. Basal cell carcinoma may originate from basal cells of the epidermis. It almost never metastasizes, and it is easily cured. Squamous cell carcinoma does metastasize. Both tumors are common, especially in the elderly and in those overexposed to the Sun. Malignant melanoma derives from the same embryonic nervous tissue that produces moles. Finally, the once rare tumor called Kaposi's sarcoma has become more frequent because of AIDS.
Lesions
The appearance of abnormal changes, or lesions, in the skin is an important element in diagnosis and treatment. Various lesions can occur, not all of them diseases related. A flat lesion of a color differing from surrounding skin is called a Freckle. A papule is a solid, elevated by superficial mass, such as a raised Mole or a Wart. A wheal is a transitory lesion resulting from an allergic response, such as to an insect bite. A nodule is a solid mass that extends deeper, such as in certain tumors and cysts. A vesicle is a tiny blister filled with clear fluid, such as in early chicken pox. A bulla is a large blister, most often seen as the result of a coloration caused by deposits of blood or blood pigments within the skin.
The appearance of such lesions may be modified by secondary changes. These include scales or flakes of dead skin, as seen in Psoriasis and Dandruff; crusts, typically dried masses of material that have oozed out as in impetigo; fissures, or sharp breaks, as seen in athlete's foot; Ulcers, or destruction of one or more skin layers, exposing underlying tissue replacing lost tissue; and lichenification, a thickened scaly area in which normal skin creases and lines are exaggerated. Lesions may be seen in several different lesions.
Malignant Tumors
Any metastasizing tumor from else where in the body may appear in the skin. Many malignant tumors also originate in the skin. Four should be mentioned. Basal cell carcinoma may originate from basal cells of the epidermis. It almost never metastasizes, and it is easily cured. Squamous cell carcinoma does metastasize. Both tumors are common, especially in the elderly and in those overexposed to the Sun. Malignant melanoma derives from the same embryonic nervous tissue that produces moles. Finally, the once rare tumor called Kaposi's sarcoma has become more frequent because of AIDS.
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