Hematology, also spelled haematology (from the Greek haima "blood" and -?o?), is the study of blood, the blood-forming organs, and blood diseases. Hematology includes the study of etiology, diagnosis, treatment, prognosis, and prevention of blood diseases that affect the production of blood and its components, such as blood cells, hemoglobin, blood proteins, and the mechanism of coagulation. The laboratory work that goes into the study of blood is frequently performed by a medical technologist. Hematologists also conduct studies in oncologythe medical treatment of cancer. Physicians specialized in hematology are known as hematologists or haematologists. Their routine work mainly includes the care and treatment of patients with hematological diseases, although some may also work at the hematology laboratory viewing blood films and bone marrow slides under the microscope, interpreting various hematological test results. In some institutions, hematologists also manage the hematology laboratory. Physicians who work in hematology laboratories, and most commonly manage them, are pathologists specialized in the diagnosis of hematological diseases, referred to as hematopathologists. Hematologists and hematopathologists generally work in conjunction to formulate a diagnosis and deliver the most appropriate therapy if needed. Hematology is a distinct subspecialty of internal medicine, separate from but overlapping with the subspecialty of medical oncology. Hematologists may specialize

further or have special interests, for example, in: treating bleeding disorders such as hemophilia and idiopathic thrombocytopenic purpura treating hematological malignacies such as lymphoma and leukemia treating hemoglobinopathies in the science of blood transfusion and the work of a blood bank in bone marrow and stem cell transplantation. Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. In vertebrates, it is composed of blood cells suspended in a liquid called blood plasma. Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume),[1] and contains dissipated proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and blood cells themselves. Albumin is the main protein in plasma, and it functions to regulate the colloidal osmotic pressure of blood. The blood cells are mainly red blood cells (also called RBCs or erythrocytes) and white blood cells, including leukocytes and platelets. The most abundant cells in vertebrate blood are red blood cells. These contain hemoglobin, an iron-containing protein, which facilitates transportation of oxygen by reversibly binding to this respiratory gas and greatly increasing its solubility in blood. In contrast, carbon dioxide is almost entirely transported extracellularly dissolved in plasma as bicarbonate ion.