BLOOD Disorders

Hematopoiesis (Blood Cell Formation) All blood cells differentiate from a common source, hemocytoblast stem cells in red bone marrow.

Anemia A decrease in the oxygen-carrying ability of the blood. Caused by: Excessive RBC destruction (hemolysis) Blood loss (acute or chronic) Inadequate RBC production

Hemorrhagic Anemia Decrease in RBC number Sudden hemorrhage

Hemolytic Anemia Decrease in RBC number Lysis of RBCs as a result of bacterial infections

Pernicious Anemia Decrease in RBC number Lack of Vitamin B12

Aplastic Anemia Decrease in RBC number Depression or destruction of bone marrow by cancer, radiation, or certain medications

Iron Deficiency Anemia Inadequate hemoglobin content in RBCs Lack of iron in diet or slow/prolonged bleeding which depletes iron reserves needed to make hemoglobin Iron deficiency anemia is the most common anemia. It occurs when the diet is low in iron or the absorption of iron is not sufficient. Sometimes the body cannot form hemoglobin. These cells were taken from a patient with iron deficiency. The cells arrived in the circulation without enough hemoglobin to carry an adequate amount of oxygen to all parts of the body.

Sickle Cell Anemia Abnormal hemoglobin in RBCs Genetic defect leads to abnormal hemoglobin, which becomes sharp and sickle shaped.

Polycythemia Excessive or abnormal increase in the number of RBCs May result from bone marrow cancer or from living at high altitudes.

Leukemia Excessive production of abnormal WBCs Bone marrow is cancerous and huge numbers of WBCs are turned out rapidly. Although this might not appear to present a problem, the “newborn” WBCs are immature and incapable of carrying out their normal protective functions.

Infectious Mononucleosis Excessive production of abnormal WBCs The virus replicates first within epithelial cells in the pharynx (which causes pharyngitis, or sore throat), and later primarily within B cells (which are invaded via their CD21). The host immune response involves cytotoxic (CD8- positive) T cells against infected B lymphocytes, resulting in enlarged atypical lymphocytes (Downey cells).

Undesirable Clotting Thrombus – a clot that develops and persists in an unbroken blood vessel Embolus – if a thrombus breaks away from the vessel wall and floats freely in the blood stream

Bleeding Disorders Thrombocytopenia results from an insufficient number of circulating platelets. Even normal movement cause spontaneous bleeding from small blood vessels. Hemophilia applies to several different hereditary bleeding disorders that result from a lack of any of the factors needed for clotting.

Developmental Aspects Before birth there are many sites of blood cell formation including the liver and spleen among others. At seven months red marrow takes over and remains so throughout life. Fetal hand grasp

Developmental Aspects Fetal hemoglobin has a greater ability to pick up oxygen since fetal blood is less oxygen rich than that of the mother. After birth these are replaced with RBCs with more typical hemoglobin. newborn

Developmental Aspects If the fetal RBCs are destroyed at such a rapid rate that the immature liver cannot rid the body of hemoglobin breakdown products in the bile fast enough, the infant becomes jaundiced. Jaundiced baby