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Hematology Hematology Facts: Average body holds 10 – 12 pints of blood. The heart circulates the blood through the circulatory system more than xs per day. About 70,000 miles of vessels. Blood contained in closed systems known as blood vessels. The largest being the Aorta and the smallest veins. Blood contains about 25 trillion cells; and every second the body replaces 8 million old red cells with 8 million new RBCs. 1,000 Hematology Function of the blood Supplies the body cells with nutrients and oxygen. Carries away carbon dioxide and urea (waste product of normal cells) Carbon dioxide is carried in the blood to the lungs, where it is exhaled as part of normal breathing. The blood carries urea to the kidneys, where it is excreted in the urine with other body wastes. Distributes enzymes, hormones and other chemicals needed for control and regulation of body activities. Blood functions to maintain the body at a uniform temperature. Keep other body fluids in a state of pH balance. Hormones are carried from secreting gland to the tissues where they are needed. Hematology Hematology testing Counting of RBCs, WBCs and platelets Differentiating WBCs on stained blood smears Measuring the percentage of RBCs in the blood (hematocrit) and Determining the oxygen-carrying capacity of the blood (hemoglobin) Complete Blood Count (CBC) is the laboratory procedure most frequently ordered for blood specimens. Components of CBC include: RBC; WBC; Hemoglobin (Hgb); Hematocrit (Hct);Differential WBC (on stained smear); Platelet count; RBC indicies. Hematology Whole Blood Composed of formed elements suspended in a clear, yellow, liquid portion know as Plasma. Plasma makes up approximately 55% of blood by volume. Formed elements make up 45 %; RBCs, WBCs, Platelets, . All elements have special function within the circulatory system. Erythrocytes (RBCs): Formed in the red bone marrow of the ribs, sternum, pelvis, and skull and in the ends of long bones in adults. Hematology Erythrocytes (RBCs) Nucleus of the immature form of RBCs disintegrates as the cell matures. Loss of nucleus results in the familiar shape of RBCs (Biconcave disk; thicker on the rim than in the middle.) Immature RBCs with pieces of nucleus present Biconcave shape of RBCs Hematology Erythrocytes: Transport oxygen from the lungs to the body cells and carry carbon dioxide away from cells, back to the lungs to be exhaled. Erythrocytes main constituent is the red pigment hemoglobin. Composed of iron and protein Hemoglobin actually carries the oxygen and some C02 throughout the body. RBC life span is 120 days Becomes fragile, ruptures and breaks releasing Hgb The iron is reused for formation of new RBCs Protein is converted into a bile pigment. Hematology Leukocytes (WBCs) Have a nucleus and are larger than RBCs The prime function of the leukocyte is to protect the body against infection and disease. Five types of leukocytes are classified as granular or agranular. Granulocytes or polymorphonuclear leukocytes include: Neutrophils, Eosinophils, Basophils. Characterized by heavily granular cytoplasms and segmented nuclei. Agranular leukocytes Lymphocytes, Monocytes Have a clear cytoplasm and solid nucleus. Hematology Leukocytes: Granular Phagocytic (engulf invading bacteria and viruses) Function primarily in the tissues. During inflammation, the blood carries the WBCs through dilated vessels to the site of the injury. Granular WBCs squeeze through permeable capillary walls by ameboid motion. Once at the site of infection or injury, the cells engulf the invading microorganism, creating pus, which contains dead leukocytes, bacteria and tissue cells. Hematology Agranular leukocytes Produce antibodies Classified as T cells or B cells on the basis of their functional characteristics. T cells Make up 65-80% of circulating lymphocytes and have a life span of months to years. Long lasting immunity to microbial infections. Immune response to: intracellular parasites, viruses, fungi and bacteria. Delayed hypersensitivity reactions; poison ivy or organ transplant rejection. Subdivided into several types according to their function. Hematology T cell subtypes: Cytotoxic (killer T cells) Kill foreign, virus infected and tumor cells. They produce proteins called perforans that induce cell death by punching holes in the cell membrane. Helper T cells: Most numerous type . Stimulate the activity of other T cells. Suppressor T cells: These cells inhibit the activity of other T cells. Memory T cells: Cells have long lifespan, respond quickly to presentation of the same antigen at a later date. Natural killer cells: These cells kill virus-infected cells and tumor cells without previous sensitization. Hematology Agranular WBCs: B. Cells Formed in bone marrow and then migrate to other lymph organs, where they multiply and reside. When stimulated, B cells differentiated into plasma cells that produce specific antibodies to an antigen. Antibodies circulate in the plasma or are present in secretions. Antibodies can cause cells to clump, precipitate, activate the complement system. Complement system is a seer5ies of reactions between plasma proteins that amplifies the immunologic response to foreign molecules. Activation of complement system leads to lysis of microorganisms or their phagocytosis by neutrophils. Hematology Thrombocytes / platelets Are not true cells but cytoplasmic fragments of a megakaryocyte. Smallest formed elements of the blood. They typically have a discoid shape; however, when activated, they become globular and form fingerlike cytoplasmic extensions called pseudopodia. Plasma: Highly complex liquid that is the carrier for formed elements and other substances, such as proteins, carbohydrates, fats, hormones, enzymes, mineral salts, gases and waste products. Composed of approximately 90 % water, 9% protein and 1% various other chemical substances. Hematology The End
