Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

BloodBlood is the fluid which circulates through the heart, arteries, veins, and capillaries carrying food andoxygen to all the cells in the body and returning waste products to points of separation from theblood, i.e., the kidneys, lungs, and sweat glands. The composition of the blood is as follows:BloodIIitFormed Elements (40-45%) Plasma (55-60%)I I i I IErythrocytes ] Leukocytes Water, Proteins (6-8%)RBC) ] (WBC) inorganic salts,[ and gases (91-92%)Thrombocytes(Platelets)The blood cells, or formed elements of the blood, are suspended in the fluid medium called plasmawhich normally represents fifty-five to sixty percent of blood volume. The blood test which measuresthe percent of cells compared to the total volume is called the hematocrit.The clear liquid that separates from the blood when it is allowed to clot completely is called"serum." Serum is essentially blood plasma from which fibrinogen has been removed in the processof clotting.Erythrocytes or red blood cells transport oxygen picked up in the lungs to tissues throughout thebody and return carbon dioxide to the lungs. The formation of red blood cells (erythropoiesis) takesplace in the bone marrow. After an average life of about four months, the red blood cells(erythrocytes) are destroyed in the liver and spleen. The blood count (RBC) is normally 4.5-6.0million cells per cu. ram. of blood for men and 4.5-5.5 million for women.The hemoglobin or oxygen-carrying component of blood is measured in terms of grams percent(gm. %) or grams per 100 milliliters (gm./100 ml.) of blood. The hemoglobin content of the blooddetermines the amount of oxygen that it carries and is responsible for the red color of the erythrocyteand of the blood.The red blood cell count may be lowered due to anemia or hemorrhage. It may be increased asa result of dehydration or of polycythemia 1 vera.]polycythemia--Excess in the number of erythrocytes in the blood.115