28 29 glossary

absolute neutrophil count (ANC)

a calculation of the number of circulating neutrophils, derived from the total number of white blood cells (WBCs) and the percentage of neutrophils counted in a microscope’s visual field

anemia

decreased red blood cell (RBC) count

aplasia

lack of cellular development (e.g., of cells within the bone marrow)

band cell

slightly immature neutrophil

blast cell

primitive white blood cell (WBC)

cytokines

proteins produced by leukocytes that are critical for regulation of hematopoiesis, apoptosis, and immune responses

differentiation

development of functions and characteristics that are different from those of the parent stem cell

erythrocyte

a cellular component of blood involved in the transport of oxygen and carbon dioxide (synonym: red blood cell [RBC])

erythroid cells

any cell that is or will become a mature RBC

erythropoiesis

process of the formation of RBCs

erythropoietin

hormone produced primarily by the kidneys in response to cellular hypoxia that is necessary for erythropoiesis

fibrin

filamentous protein; basis of thrombus and blood clot

fibrinogen

protein converted into fibrin to form thrombus and clot

fibrinolysis

process of breakdown of fibrin clot

granulocyte

granulated WBC (i.e., neutrophil, eosinophil, basophil)

haptoglobin

blood protein synthesized by the liver; binds free hemoglobin released from erythrocytes which is then removed by the reticuloendothelial system

hematocrit

percentage of total blood volume consisting of RBCs

hematopoiesis

complex process of the formation and maturation of blood cells

hemoglobin

iron-containing protein of RBCs; delivers oxygen to tissues

hemolysis

destruction of RBCs with release of cellular components into the circulation; may occur within or outside the vasculature

hemosiderin

iron-containing pigment derived from the breakdown of hemoglobin

hemostasis

intricate balance between clot formation and clot dissolution

hypochromia

pallor within the RBCs caused by decreased hemoglobin content

leukemia

uncontrolled proliferation of WBCs

leukocyte

one of several cellular components of blood involved in defense of the body; subtypes include neutrophils, eosinophils, basophils, monocytes, and lymphocytes (synonym: white blood cell [WBC])

leukopenia

less-than-normal amount of WBCs in circulation

lymphocyte

form of WBC involved in immune functions

lymphoid

pertaining to lymphocytes

lymphopenia

a lymphocyte count less than 1500/mm³

macrophage

reticuloendothelial cells capable of phagocytosis

megaloblastic anemia

a type of anemia characterized by abnormally large, nucleated RBCs

microcytosis

smaller-than-normal RBCs

monocyte

large WBC that becomes a macrophage when it leaves the circulation and moves into body tissues

myeloid

pertaining to nonlymphoid blood cells that differentiate into RBCs, platelets, macrophages, mast cells, and various WBCs

myelopoiesis

formation and maturation of cells derived from myeloid stem cell

natural killer (NK) cells

lymphocytes that defend against microorganisms and malignant cells

neutropenia

lower-than-normal number of neutrophils

neutrophil

fully mature WBC capable of phagocytosis; primary defense against bacterial infection

normochromic

normal RBC color, indicating normal amount of hemoglobin

normocytic

normal size of RBC

oxyhemoglobin

combined form of oxygen and hemoglobin; primarily found in arterial blood

pancytopenia

abnormal decrease in WBCs, RBCs, and platelets

petechiae

tiny capillary hemorrhages

phagocytosis

process of cellular ingestion and digestion of foreign bodies

plasma

liquid portion of blood

plasminogen

protein converted to plasmin to dissolve thrombi and clots

platelet (thrombocyte)

a cellular component of blood involved in blood coagulation

poikilocytosis

variation in shape of RBCs

polycythemia

excess RBCs

red blood cell (RBC)

a cellular component of blood involved in the transport of oxygen and carbon dioxide (synonym: erythrocyte)

reticulocytes

slightly immature RBCs, usually 1% of total number of circulating RBCs

reticuloendothelial system

complex system of cells throughout the body capable of phagocytosis

serum

portion of blood remaining after coagulation occurs

spherocytes

small, spherically shaped RBCs

stem cell

primitive cell, capable of self-replication and differentiation into myeloid or lymphoid stem cell

stroma

component of the bone marrow not directly related to hematopoiesis but serves important supportive roles in this process

thrombocyte

a cellular component of blood involved in blood coagulation (synonym: platelet)

thrombocytopenia

lower-than-normal platelet count

thrombocytosis

higher-than-normal platelet count

white blood cell (WBC)

one of several cellular components of blood involved in defense of the body; subtypes include neutrophils, eosinophils, basophils, monocytes, and lymphocytes (synonym: leukocyte)