Key Terms
ABO blood group
blood-type classification based on the presence or absence of A and B glycoproteins on the erythrocyte membrane surface
agglutination
clustering of cells into masses linked by antibodies
agranular leukocytes
leukocytes with few granules in their cytoplasm; specifically, monocytes, lymphocytes, and NK cells
albumin
most abundant plasma protein, accounting for most of the osmotic pressure of plasma
anemia
deficiency of red blood cells or hemoglobin
antibodies
(also, immunoglobulins or gamma globulins) antigen-specific proteins produced by specialized B lymphocytes that protect the body by binding to foreign objects such as bacteria and viruses
anticoagulant
substance such as heparin that opposes coagulation
antithrombin
anticoagulant that inactivates factor X and opposes the conversion of prothrombin (factor II) into thrombin in the common pathway
B lymphocytes
(also, B cells) lymphocytes that defend the body against specific pathogens and thereby provide specific immunity
basophils
granulocytes that stain with a basic (alkaline) stain and store histamine and heparin
bilirubin
yellowish bile pigment produced when iron is removed from heme and is further broken down into waste products
biliverdin
green bile pigment produced when the non-iron portion of heme is degraded into a waste product; converted to bilirubin in the liver
blood
liquid connective tissue composed of formed elements—erythrocytes, leukocytes, and platelets—and a fluid extracellular matrix called plasma; component of the cardiovascular system
bone marrow biopsy
diagnostic test of a sample of red bone marrow
bone marrow transplant
treatment in which a donor’s healthy bone marrow with its stem cells replaces diseased or damaged bone marrow of a patient
bruise
localized bleeding under the skin due to damaged blood vessels
buffy coat
thin, pale layer of leukocytes and platelets that separates the erythrocytes from the plasma in a sample of centrifuged blood
carbaminohemoglobin
compound of carbon dioxide and hemoglobin, and one of the ways in which carbon dioxide is carried in the blood
clotting factors
group of 12 identified substances active in coagulation
coagulation
formation of a blood clot; part of the process of hemostasis
colony-stimulating factors (CSFs)
glycoproteins that trigger the proliferation and differentiation of myeloblasts into granular leukocytes (basophils, neutrophils, and eosinophils)
common pathway
final coagulation pathway activated either by the intrinsic or the extrinsic pathway, and ending in the formation of a blood clot
cross matching
blood test for identification of blood type using antibodies and small samples of blood
cytokines
class of proteins that act as autocrine or paracrine signaling molecules; in the cardiovascular system, they stimulate the proliferation of progenitor cells and help to stimulate both nonspecific and specific resistance to disease
defensins
antimicrobial proteins released from neutrophils and macrophages that create openings in the plasma membranes to kill cells
deoxyhemoglobin
molecule of hemoglobin without an oxygen molecule bound to it
diapedesis
(also, emigration) process by which leukocytes squeeze through adjacent cells in a blood vessel wall to enter tissues
embolus
thrombus that has broken free from the blood vessel wall and entered the circulation
emigration
(also, diapedesis) process by which leukocytes squeeze through adjacent cells in a blood vessel wall to enter tissues
eosinophils
granulocytes that stain with eosin; they release antihistamines and are especially active against parasitic worms
erythrocyte
(also, red blood cell) mature myeloid blood cell that is composed mostly of hemoglobin and functions primarily in the transportation of oxygen and carbon dioxide
erythropoietin (EPO)
glycoprotein that triggers the bone marrow to produce RBCs; secreted by the kidney in response to low oxygen levels
extrinsic pathway
initial coagulation pathway that begins with tissue damage and results in the activation of the common pathway
ferritin
protein-containing storage form of iron found in the bone marrow, liver, and spleen
fibrin
insoluble, filamentous protein that forms the structure of a blood clot
fibrinogen
plasma protein produced in the liver and involved in blood clotting
fibrinolysis
gradual degradation of a blood clot
formed elements
cellular components of blood; that is, erythrocytes, leukocytes, and platelets
globin
heme-containing globular protein that is a constituent of hemoglobin
globulins
heterogeneous group of plasma proteins that includes transport proteins, clotting factors, immune proteins, and others
granular leukocytes
leukocytes with abundant granules in their cytoplasm; specifically, neutrophils, eosinophils, and basophils
hematocrit
(also, packed cell volume) volume percentage of erythrocytes in a sample of centrifuged blood
hematopoietic stem cell
type of pluripotent stem cell that gives rise to the formed elements of blood (hemocytoblast)
heme
red, iron-containing pigment to which oxygen binds in hemoglobin
hemocytoblast
hematopoietic stem cell that gives rise to the formed elements of blood
hemoglobin
oxygen-carrying compound in erythrocytes
hemolysis
destruction (lysis) of erythrocytes and the release of their hemoglobin into circulation
hemolytic disease of the newborn (HDN)
(also, erythroblastosis fetalis) disorder causing agglutination and hemolysis in an Rh+ fetus or newborn of an Rh− person
hemophilia
genetic disorder characterized by inadequate synthesis of clotting factors
hemopoiesis
production of the formed elements of blood
hemopoietic growth factors
chemical signals including erythropoietin, thrombopoietin, colony-stimulating factors, and interleukins that regulate the differentiation and proliferation of particular blood progenitor cells
hemorrhage
excessive bleeding
hemosiderin
protein-containing storage form of iron found in the bone marrow, liver, and spleen
hemostasis
physiological process by which bleeding ceases
heparin
short-acting anticoagulant stored in mast cells and released when tissues are injured, opposes prothrombin
hypoxemia
below-normal level of oxygen saturation of blood (typically <95 percent)
immunoglobulins
(also, antibodies or gamma globulins) antigen-specific proteins produced by specialized B lymphocytes that protect the body by binding to foreign objects such as bacteria and viruses
interleukins
signaling molecules that may function in hemopoiesis, inflammation, and specific immune responses
intrinsic pathway
initial coagulation pathway that begins with vascular damage or contact with foreign substances, and results in the activation of the common pathway
jaundice
yellowing of the skin or whites of the eyes due to excess bilirubin in the blood
leukemia
cancer involving leukocytes
leukocyte
(also, white blood cell) colorless, nucleated blood cell, the chief function of which is to protect the body from disease
leukocytosis
excessive leukocyte proliferation
leukopenia
below-normal production of leukocytes
lymphocytes
agranular leukocytes of the lymphoid stem cell line, many of which function in specific immunity
lymphoid stem cells
type of hematopoietic stem cells that gives rise to lymphocytes, including various T cells, B cells, and NK cells, all of which function in immunity
lymphoma
form of cancer in which masses of malignant T and/or B lymphocytes collect in lymph nodes, the spleen, the liver, and other tissues
lysozyme
digestive enzyme with bactericidal properties
macrophage
phagocytic cell of the myeloid lineage; a matured monocyte
megakaryocyte
bone marrow cell that produces platelets
memory cell
type of B or T lymphocyte that forms after exposure to a pathogen
monocytes
agranular leukocytes of the myeloid stem cell line that circulate in the bloodstream; tissue monocytes are macrophages
myeloid stem cells
type of hematopoietic stem cell that gives rise to some formed elements, including erythrocytes, megakaryocytes that produce platelets, and a myeloblast lineage that gives rise to monocytes and three forms of granular leukocytes (neutrophils, eosinophils, and basophils)
natural killer (NK) cells
cytotoxic lymphocytes capable of recognizing cells that do not express “self” proteins on their plasma membrane or that contain foreign or abnormal markers; provide generalized, nonspecific immunity
neutrophils
granulocytes that stain with a neutral dye and are the most numerous of the leukocytes; especially active against bacteria
oxyhemoglobin
molecule of hemoglobin to which oxygen is bound
packed cell volume (PCV)
(also, hematocrit) volume percentage of erythrocytes present in a sample of centrifuged blood
plasma
in blood, the liquid extracellular matrix composed mostly of water that circulates the formed elements and dissolved materials throughout the cardiovascular system
plasmin
blood protein active in fibrinolysis
platelet plug
accumulation and adhesion of platelets at the site of blood vessel injury
platelets
(also, thrombocytes) one of the formed elements of blood that consists of cell fragments broken off from megakaryocytes
pluripotent stem cell
stem cell that derives from totipotent stem cells and is capable of differentiating into many, but not all, cell types
polycythemia
elevated level of hemoglobin, whether adaptive or pathological
polymorphonuclear
having a lobed nucleus, as seen in some leukocytes
positive chemotaxis
process in which a cell is attracted to move in the direction of chemical stimuli
red blood cells (RBCs)
(also, erythrocytes) one of the formed elements of blood that transports oxygen
reticulocyte
immature erythrocyte that may still contain fragments of organelles
Rh blood group
blood-type classification based on the presence or absence of the antigen Rh on the erythrocyte membrane surface
serum
blood plasma that does not contain clotting factors
sickle cell disease
(also, sickle cell anemia) inherited blood disorder in which hemoglobin molecules are malformed, leading to the breakdown of RBCs that take on a characteristic sickle shape
T lymphocytes
(also, T cells) lymphocytes that provide cellular-level immunity by physically attacking foreign or diseased cells
thalassemia
inherited blood disorder in which maturation of RBCs does not proceed normally, leading to abnormal formation of hemoglobin and the destruction of RBCs
thrombin
enzyme essential for the final steps in formation of a fibrin clot
thrombocytes
platelets, one of the formed elements of blood that consists of cell fragments broken off from megakaryocytes
thrombocytopenia
condition in which there are too few platelets, resulting in abnormal bleeding (hemophilia)
thrombocytosis
condition in which there are too many platelets, resulting in abnormal clotting (thrombosis)
thrombopoietin
hormone secreted by the liver and kidneys that prompts the development of megakaryocytes into thrombocytes (platelets)
thrombosis
excessive clot formation
thrombus
aggregation of fibrin, platelets, and erythrocytes in an intact artery or vein
tissue factor
protein thromboplastin, which initiates the extrinsic pathway when released in response to tissue damage
totipotent stem cell
embryonic stem cell that is capable of differentiating into any and all cells of the body; enabling the full development of an organism
transferrin
plasma protein that binds reversibly to iron and distributes it throughout the body
universal donor
individual with type O− blood
universal recipient
individual with type AB+ blood
vascular spasm
initial step in hemostasis, in which the smooth muscle in the walls of the ruptured or damaged blood vessel contracts
white blood cells (WBCs)
(also, leukocytes) one of the formed elements of blood that provides defense against disease agents and foreign materials