Week 1: The Formed Elements of Blood

Vocabulary flashcards covering key terms, cells, proteins, disorders, and processes related to the formed elements of blood, their functions, homeostasis, and clinical significance.

Erythrocyte (Red Blood Cell)

Most numerous formed element; biconcave, anucleate cell that transports O₂ and CO₂ and is packed with hemoglobin.

Leukocyte (White Blood Cell)

Immune‐function cell that retains organelles and combats pathogens, toxins, and tissue damage.

Platelet (Thrombocyte)

Megakaryocyte fragment that helps achieve hemostasis by forming plugs, releasing clotting chemicals, and promoting repair.

Hemostasis

The cessation of bleeding via vascular spasm, platelet plug formation, and coagulation.

Hemoglobin (Hb)

Gas-transport protein of four globins and four heme groups; each Hb binds up to four O₂ molecules.

Hematocrit

Percentage of whole blood volume occupied by erythrocytes; higher in males than females.

Hematopoiesis (Hemopoiesis)

General process of formed-element production from hematopoietic stem cells in red bone marrow.

Erythropoiesis

Specific production of erythrocytes, stimulated by the hormone erythropoietin.

Erythropoietin (EPO)

Kidney-secreted hormone that increases RBC production in response to hypoxemia.

Hypoxemia

Deficiency of oxygen in the blood that triggers increased EPO release.

Hemolysis

Rupture and destruction of erythrocytes, releasing hemoglobin.

Transferrin

Plasma protein that transports recycled iron released from degraded heme.

Biliverdin

Green pigment produced from heme breakdown before conversion to bilirubin.

Bilirubin

Yellow-green pigment derived from biliverdin; transported by albumin and excreted in bile.

Urobilinogen

Intestinal conversion product of bilirubin that imparts brown color to feces.

Polycythemia

Excessive RBC count leading to increased blood viscosity, volume, and pressure.

Primary Polycythemia

RBC excess caused by bone-marrow cancer; hematocrit may reach 80%.

Secondary Polycythemia

RBC excess resulting from hypoxia-inducing conditions such as high altitude, smoking, or dehydration.

Anemia

Deficiency of RBCs or Hb causing reduced oxygen-carrying capacity.

Pernicious Anemia

Anemia due to lack of intrinsic factor and thus vitamin B₁₂ absorption.

Iron-Deficiency Anemia

Anemia caused by inadequate iron for hemoglobin synthesis.

Thalassemia

Inherited anemia characterized by impaired globin chain production.

Aplastic Anemia

Anemia stemming from reduced erythrocyte mitosis in red bone marrow.

Sickle-Cell Anemia

Hereditary disorder producing HbS that sickles in low O₂, blocking vessels but conferring malaria resistance.

Hemorrhagic Anemia

Anemia attributable to blood loss.

Hemolytic Anemia

Anemia caused by premature RBC destruction (e.g., transfusion reaction, parasites).

Antigen

Genetically unique surface molecule that enables immune system to distinguish self from non-self.

Antibody

Plasma protein that binds specific antigens, causing agglutination or destruction of foreign cells.

Agglutination

Clumping of cells by antibodies binding multiple antigens simultaneously.

Type A Blood

RBCs possess A antigens and plasma contains anti-B antibodies.

Type B Blood

RBCs possess B antigens and plasma contains anti-A antibodies.

Type AB Blood

RBCs possess both A and B antigens; plasma lacks anti-A and anti-B—universal recipient.

Type O Blood

RBCs lack A and B antigens; plasma has both anti-A and anti-B—universal donor.

Rh Factor (Antigen D)

Surface protein determining + or – blood type; presence = Rh⁺, absence = Rh⁻.

Erythroblastosis Fetalis (HDN)

Hemolytic disease of newborn caused by maternal anti-D antibodies attacking Rh⁺ fetal RBCs.

RhoGAM

Rh immune globulin given to Rh⁻ mothers to prevent anti-D antibody formation.

Granulocyte

Leukocyte category with visible cytoplasmic granules: neutrophils, eosinophils, basophils.

Agranulocyte

Leukocyte category lacking visible granules: lymphocytes and monocytes.

Neutrophil

Most abundant WBC (60-70%); multi-lobed nucleus; phagocytizes bacteria and releases antimicrobials.

Eosinophil

2-4% of WBCs; red-orange granules; combats parasitic worms and modulates allergens/inflammation.

Basophil

Rarest WBC (<0.5%); dark granules; releases histamine, heparin, and serotonin to promote inflammation.

Monocyte

Largest WBC (3-8%); transforms into macrophage for phagocytosis and antigen presentation.

Lymphocyte

Second-most abundant WBC (25-35%); central to adaptive immunity; includes B and T cells.

B Lymphocyte

Lymphocyte that matures in bone marrow and differentiates into antibody-producing plasma cells.

T Lymphocyte

Lymphocyte that matures in thymus and directly attacks infected or abnormal cells.

Leukopenia

WBC count below 5,000/µL, often due to poisoning, radiation, or viral infections.

Leukocytosis

Elevated WBC count above 10,000–11,000/µL, usually indicating infection or inflammation.

Leukemia

Cancer of hematopoietic tissues producing excessive, nonfunctional leukocytes.

Myeloid Leukemia

Leukemia involving uncontrolled granulocyte production.

Lymphoid Leukemia

Leukemia involving uncontrolled lymphocyte production.

Acute Leukemia

Rapid-onset leukemia that can be fatal within months if untreated.

Chronic Leukemia

Slow-developing leukemia that may remain undetected for months.

Leukopoiesis

Formation of leukocytes from hematopoietic stem cells in bone marrow.

Thrombopoiesis

Formation of platelets regulated by thrombopoietin.

Thrombopoietin

Hormone from liver and kidneys that stimulates megakaryocytes to produce platelets.

Megakaryocyte

Large bone-marrow cell whose cytoplasmic fragments become platelets.

Vascular Spasm

Immediate vasoconstriction of damaged vessel to reduce blood loss.

Platelet Plug

Aggregate of platelets adhering to exposed collagen to temporarily seal vessel breaks.

Coagulation

Cascade converting fibrinogen to fibrin to form a stable blood clot.

Extrinsic Pathway

Coagulation route initiated by tissue factors released outside blood.

Intrinsic Pathway

Coagulation route initiated by factors present within blood.

Factor X

Clotting factor where intrinsic and extrinsic pathways converge; forms prothrombin activator.

Prothrombin Activator

Enzyme complex (Factor X + Factor III + Ca²⁺) that converts prothrombin to thrombin.

Prothrombin

Plasma protein precursor that thrombin is formed from during coagulation.

Thrombin

Enzyme that converts soluble fibrinogen into insoluble fibrin strands.

Fibrinogen

Soluble plasma protein converted to fibrin during clotting.

Fibrin

Sticky, insoluble protein mesh that stabilizes blood clots.

Fibrinolysis

Dissolution of a blood clot by plasmin after tissue repair.

Kallikrein

Enzyme that converts plasminogen to plasmin in fibrinolysis.

Plasmin

Active enzyme that digests fibrin and dissolves clots.

Antithrombin

Liver-produced anticoagulant that deactivates thrombin.

Heparin

Basophil-secreted anticoagulant that blocks thrombin activity.

Platelet Repulsion

Non-stick quality of healthy endothelium due to prostacyclin coating that prevents unwarranted clotting.

Thrombus

Clot formed in an unbroken vessel, potentially obstructing blood flow.

Embolus

A dislodged thrombus traveling through the bloodstream; can block distant vessels.

Hemophilia

Sex-linked recessive disorder lacking specific clotting factors, leading to prolonged bleeding.

Hemophilia A

Most common hemophilia caused by deficiency of Factor VIII.

Hemophilia B

Hemophilia caused by deficiency of Factor IX.

Hemophilia C

Rare hemophilia caused by deficiency of Factor XI.

Hematoma

Localized mass of clotted blood outside vessels, commonly called a bruise.

Histamine

Basophil chemical that induces vasodilation during inflammation.

Serotonin (in clotting)

Basophil and platelet chemical that attracts neutrophils and prolongs vascular spasm.

Globulins

Plasma proteins that include antibodies and transport proteins.

Albumin

Most abundant plasma protein; transports substances and maintains osmotic pressure.