Blood Disorders
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Biology of BloodBlood is a complex mixture of
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Symptoms and Diagnosis of Blood DisordersDisorders that affect the blood are called blood disorders or hematologic disorders. There are many blood disorders, and they can affect the quantity as well as the function of the cells in the blood (blood cells) or proteins in the blood clotting system or immune system.
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AnemiaAnemia is a condition in which the number of red blood cells is low.
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Bleeding Due to Abnormal Blood VesselsBleeding may result from abnormalities in
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Bleeding Due to Clotting DisordersBlood clotting (coagulation) disorders are dysfunctions in the body's ability to control the formation of blood clots. These dysfunctions may result in
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Blood Clotting ProcessHemostasis is the body's way of stopping injured blood vessels from bleeding. Hemostasis includes clotting of the blood.
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Blood TransfusionA blood transfusion is the transfer of blood or a blood component from one healthy person (a donor) to a sick person (a recipient). Transfusions are given to increase the blood's ability to carry oxygen, restore the amount of blood in the body (blood volume), and correct clotting problems.
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Excessive ClottingExcessive clotting (thrombophilia) occurs when the blood clots too easily or excessively.
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Iron OverloadIron is essential for life, so the body usually tightly controls iron absorption from food and recycles the iron from red blood cells. People lose small amounts of iron every day, and even a healthy diet contains only a small amount of iron. Thus, people rarely have too much iron in their body. Causes of excess iron in the body (iron overload) include the following:
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LeukemiasLeukemias are cancers of white blood cells or of cells that develop into white blood cells.
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LymphomasLymphomas are cancers of lymphocytes, which reside in the lymphatic system and in blood-forming organs.
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Myeloproliferative DisordersIn myeloproliferative neoplasms (myelo = bone marrow; proliferative = rapid multiplication; and neoplasm = new abnormal growth, such as a precancer or cancer), the blood-producing cells in the bone marrow (precursor cells, also called stem cells) develop and reproduce excessively or are crowded out by an overgrowth of fibrous tissue. Sometimes, blood-producing cells appear and reproduce in the spleen and liver. Myeloproliferative neoplasms are caused by genetic mutations. Typically the mutations are acquired and not inherited, although rarely there are families in which several members have these disorders.
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Plasma Cell DisordersPlasma cell disorders are uncommon. They begin when a single plasma cell multiplies excessively. The resulting group of genetically identical cells (called a clone) produces a large quantity of a single type of antibody (immunoglobulin). Plasma cells develop from B cells ( B lymphocytes), a type of white blood cell that normally produces antibodies. These proteins help the body fight infection.
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Platelet DisordersPlatelets (sometimes called thrombocytes) are cell fragments produced in the bone marrow that circulate in the bloodstream and help blood to clot. Thrombopoietin, primarily produced in the liver, stimulates the bone marrow to make large cells (megakaryocytes), which in turn make platelets from material inside their cell body (cytoplasm). Platelets that are not used in clots circulate for 7 to 10 days and are then destroyed. About one third are always stored in the spleen.
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Spleen DisordersThe spleen, a spongy, soft organ about as big as a person’s fist, is located in the upper left part of the abdomen, just under the rib cage. The splenic artery brings blood to the spleen from the heart. Blood leaves the spleen through the splenic vein, which drains into a larger vein (the portal vein) that carries the blood to the liver. The spleen has a covering of fibrous tissue (the splenic capsule) that supports its blood vessels and lymphatic vessels.
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White Blood Cell DisordersWhite blood cells (leukocytes) are an important part of the body’s defense against infectious organisms and foreign substances ( the immune system). To defend the body adequately, a sufficient number of white blood cells must receive a message that an infectious organism or foreign substance has invaded the body, get to where they are needed, and then kill and digest the harmful organism or substance (see figure ).
