Hematology

Hematology, also spelled haematology, is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to blood. Hematologists focus largely on lymphatic organs and bone marrow and may diagnose blood count irregularities or platelet irregularities. Hematologists treat organs that are fed by blood cells, including the lymph nodes, spleen, thymus and lymphoid tissue. Blood is made up of several parts, including red blood cells, white blood cells, platelets and plasma. Red blood cells, which make up about 45% of whole blood, carry oxygen from the lungs to the body’s tissue. Platelets are derived from bone marrow cells called megakaryocytes. Megakaryocytes are huge cells that break into fragments to form platelets. These cell fragments have no nucleus but do contain structures called granules. The granules house proteins that are necessary for clotting blood and sealing breaks in blood vessels. Hemoglobin (or haemoglobin) is a protein in red blood cells which contains iron. It is used to transport oxygen around the human body. Hemoglobin is found in the red blood cells of all vertebrates apart from white-blooded fish. It also occurs in some invertebrates. Some other invertebrates use other chemicals such as hemocyanin. This book is comprehensive and practical enough to be a complete resource for the ophthalmologist, ophthalmology resident, optometrist, as well as family physicians, medical students.