Topic 1- Blood

Cardiovascular System

Composed of the blood, heart, and blood vessels that transport materials between the heart and body tissues.

Blood

A connective tissue that transports gases, nutrients, hormones, and waste products throughout the body.

Heart

A muscular pump that propels blood through the circulatory system.

Blood Vessels

Pathways that circulate blood between the heart and tissues; include arteries, arterioles, capillaries, venules, and veins.

Functions of Blood

Distribution (O₂, CO₂, nutrients, hormones), regulation (pH, temperature, volume), and protection (against infection and blood loss).

Plasma

The fluid portion of blood; 90% water and 10% solutes including proteins, nutrients, electrolytes, and gases.

Formed Elements

The cellular components of blood—erythrocytes, leukocytes, and platelets.

Hematocrit

The percentage of total blood volume composed of red blood cells; averages 47% ± 5% in males and 42% ± 5% in females.

Physical Characteristics of Blood

Sticky, opaque, slightly salty, scarlet to dark red in color, pH 7.35–7.45, and 3–5× more viscous than water.

Albumin

The most abundant plasma protein; maintains osmotic pressure, transports hormones and fatty acids, binds calcium, and acts as a buffer.

Globulins

Plasma proteins that include transport proteins (alpha and beta) and antibodies (gamma).

Clotting Proteins

Plasma proteins made by the liver (including fibrinogen and prothrombin) that function in coagulation.

Non-Protein Nitrogen Substances (NPNs)

Waste products such as urea, uric acid, creatinine, and ammonium salts from protein metabolism.

Erythrocyte (RBC)

A biconcave, anucleate cell that carries O₂ and CO₂; uses anaerobic metabolism.

Hemoglobin

The iron-containing protein in RBCs that binds O₂ and CO₂; gives blood its color.

Hematopoiesis

Formation of blood cells in red bone marrow.

Erythropoiesis

Production of red blood cells from hemocytoblasts under the influence of erythropoietin.

Erythropoietin (EPO)

A glycoprotein hormone produced by the kidneys and liver that stimulates RBC production in response to hypoxia.

Reticulocyte

An immature RBC containing remnants of ribosomal RNA; matures into an erythrocyte within ~48 hours.

Hemochromatosis

A disorder caused by excessive iron absorption and storage in the liver, skin, heart, and endocrine organs.

Polycythemia

An excess number of RBCs (>7×10⁶/mm³).

Anemia

A condition in which blood has abnormally low O₂-carrying capacity due to reduced RBCs or hemoglobin.

Iron-Deficiency Anemia

Caused by inadequate iron for hemoglobin synthesis; results in microcytic, hypochromic RBCs.

Pernicious Anemia

Caused by lack of vitamin B₁₂ or intrinsic factor needed for absorption.

Sickle Cell Anemia

Genetic disorder causing abnormal hemoglobin that distorts RBC shape and reduces O₂ transport.

Thalassemia

Genetic disorder resulting in abnormal globin chain synthesis.

Leukocyte (WBC)

Nucleated blood cell that provides defense against pathogens and foreign substances.

Leukopoiesis

Production of WBCs stimulated by interleukins and colony-stimulating factors.

Neutrophil

Most abundant WBC (50–70%); multi-lobed nucleus; pale granules; phagocytic and quick-acting.

Eosinophil

Granulocyte with red-staining granules; antiparasitic and anti-allergy functions.

Basophil

Least abundant WBC; blue-staining granules containing histamine and heparin.

Lymphocyte

Agranulocyte with large nucleus; includes T cells (attack antigens) and B cells (produce antibodies).

Monocyte

Largest WBC; kidney-shaped nucleus; differentiates into macrophages in tissues.

Leukopenia

WBC count below 4,000/mm³; increases infection risk.

Leukocytosis

WBC count above 11,000/mm³; occurs with infection, inflammation, or malignancy.

Leukemia

Cancer of WBCs characterized by excessive, abnormal leukocyte production.

Infectious Mononucleosis

Viral infection (Epstein-Barr Virus) causing proliferation of B lymphocytes; symptoms include fever, sore throat, and enlarged lymph nodes.

Platelets (Thrombocytes)

Cell fragments (2–4 µm) from megakaryocytes involved in hemostasis.

Thrombopoietin

Hormone that regulates platelet production.

Hemostasis

The stoppage of bleeding through vascular spasm, platelet plug formation, and coagulation.

Von Willebrand Factor

Protein produced by platelets and endothelial cells that helps platelets adhere to damaged vessel walls.

Coagulation

Transformation of blood into a semisolid clot through intrinsic and extrinsic pathways.

Calcium (Ca²⁺)

Ion required for both intrinsic and extrinsic clotting pathways.

Clot Retraction

Process where platelets contract using actin and myosin to tighten and stabilize the clot.

Fibrinolysis

Enzymatic breakdown of fibrin by plasmin after vessel healing.

Prostacyclin & Nitric Oxide (NO)

Chemicals produced by endothelium that prevent unwanted clotting.

Antithrombin III

Liver product that inhibits activated clotting factors and limits coagulation.

Heparin

Natural anticoagulant that enhances antithrombin activity; also used clinically to prevent clotting.

Warfarin / Coumadin

Vitamin K inhibitors used to prevent clot formation.

QuickClot®

Hemostatic agent that absorbs water from blood, concentrating clotting factors and platelets to promote rapid clotting.

Hirudin

Anticoagulant produced by the medicinal leech (Hirudo medicinalis) that inactivates thrombin.

Thrombus

A clot that develops and persists in an unbroken vessel or heart chamber.

Embolus

A free-floating intravascular clot.

Disseminated Intravascular Coagulation (DIC)

Systemic thrombohemorrhagic disorder with unregulated fibrin formation and accelerated fibrinolysis.

Thrombocytopenia

Platelet count below 50,000/mm³, which can cause spontaneous bleeding.

Petechiae

Pinpoint hemorrhages in capillaries of the skin or mucous membranes.

Hemophilia

Inherited bleeding disorder caused by deficient clotting factors VIII (A), IX (B), or XI.

Prothrombin Time (PT)

Measures efficiency of the extrinsic and common clotting pathways.

Partial Thromboplastin Time (PTT)

Measures efficiency of the intrinsic and common pathways.

Agglutinogen

Glycoprotein on RBC surface that can trigger antibody formation in non-compatible hosts.

Agglutinin

Antibody found in plasma that reacts with foreign agglutinogens, causing clumping.

Rh Factor

Group of antigens (C, D, E, c, e) on RBCs; D is the most immunogenic and determines Rh⁺ or Rh⁻ status.

Rh⁻ Individual

Lacks C, D, and E antigens and develops anti-D agglutinins after exposure to Rh⁺ blood.

Hemolytic Disease of the Newborn (Erythroblastosis Fetalis)

Disorder caused by Rh incompatibility where maternal anti-D antibodies attack fetal RBCs.

Rhogam

Preventive treatment for Rh⁻ mothers that prevents production of anti-D agglutinins.

Hemolytic Transfusion Reaction

Reaction caused by mismatched blood transfusion leading to RBC destruction; often due to human error or weak agglutinogens.

Erythrocyte Degradation (RBC Breakdown)

Aged or damaged RBCs are engulfed by macrophages in the liver, spleen, and bone marrow.

Coagulation Pathways (Intrinsic vs. Extrinsic)

Intrinsic Pathway: All factors in blood; slower (3–6 min). Extrinsic Pathway: Triggered by tissue factor (TF) from damaged cells; faster (~15 sec). Both activate Factor X, forming prothrombin activator → converts prothrombin → thrombin, which converts fibrinogen → fibrin.