Cardiovascular System: Blood Vocabulary//STUDIED

Cardiovascular System: An Introduction

• Circulating transport system.

• Transports oxygen, carbon dioxide, nutrients, waste, hormones, and immune components.

• Composition:

  • Heart: pump.

  • Blood vessels: conducting system.

  • Blood: fluid medium.

The Nature of Blood

• Specialized fluid connective tissue.

• Contains cells in a fluid matrix.

• Functions:

  • Transport of gases, nutrients, hormones, wastes.

  • Regulation of pH and ions.

  • Restriction of fluid loss (clotting).

  • Defense: antibodies and immune cells.

  • Stabilization of body temperature.

• Components:

  • Plasma (50-60% of blood volume):

    • Water (90% of plasma).

    • Plasma proteins:

      • Albumins (60%): transport substances.

      • Globulins (35%): immunoglobulins and transport.

      • Fibrinogen (4%): clotting.

  • Formed elements:

    • Red blood cells (RBCs, erythrocytes): oxygen transport (99.9% of formed elements).

    • White blood cells (WBCs, leukocytes): immune system.

    • Platelets (thrombocytes): clotting.

• Physical characteristics:

  • Temperature: 38°C (100.4°F).

  • High viscosity

  • pH: slightly alkaline (7.35 – 7.45).

Red Blood Cells

• Measurement:

  • RBC count: 4.5 – 6.3 million /cubic millimeter

  • Hematocrit: 40-52%.

• Structure:

  • Biconcave disc: high surface-to-volume ratio, rouleaux formation, flexibility.

  • No nuclei, mitochondria, or ribosomes; lifespan ~120 days.

• Hemoglobin (Hgb):

  • Structure: four globulin molecules + heme (iron unit).

  • Function:

    • Oxyhemoglobin: hemoglobin + oxygen (bright red).

    • Deoxyhemoglobin: hemoglobin without oxygen (darker red).

    • Fetal hemoglobin: stronger bond with oxygen.

    • Anemia: decreased oxygen carrying capacity.

• RBC Turnover:

  • 1% replaced daily (~3 million/second).

  • Monitored by macrophages, liver, and spleen.

  • Phagocytes break down hemoglobin into:

    • Amino acids.

    • Biliverdin -> bilirubin (jaundice).

    • Iron (stored as ferritin).

  • Hemoglobinuria: Hgb in urine.

  • Hematuria: RBCs in urine.

• RBC Production (erythropoeisis):

  • In red bone marrow.

  • Myeloid stem cells -> RBCs.

  • Lymphoid stem cells -> lymphocytes.

  • Reticulocytes mature in bloodstream.

  • Stimulated by erythropoietin (kidneys) in response to hypoxia.

• Blood Types:

  • Surface antigens: A, B, Rh.

  • Types: A, B, AB, O.

    • Rh positive: Rh antigen present.

    • Rh negative: Rh antigen absent.

  • Transfusion reactions:

    • Type A: anti-B antibodies.

    • Type B: anti-A antibodies.

    • Type AB: no anti-A or anti-B antibodies.

    • Type O: both anti-A and anti-B antibodies.

  • Rh reactions require prior exposure.

  • Cross-match for compatibility.

  • Type O: universal donor (RBCs only).

White Blood Cells

• Functions:

  • Defend against pathogens.

  • Remove toxins and wastes.

  • Dismantle damaged cells.

• Locations:

  • Connective tissue and lymphatic organs.

  • Diapedesis: movement into tissues.

• Characteristics:

  • Migrate out of bloodstream.

  • Amoeboid movement.

  • Chemotaxis.

  • Phagocytosis (neutrophils, eosinophils, monocytes).

• Types:

  • Neutrophils (50-70%): phagocytosis, first at injury, form pus.

  • Eosinophils (2-4%): excrete toxins against parasites, allergic reactions.

  • Basophils (<1%): histamine, heparin.

  • Monocytes (2-8%): become macrophages.

  • Lymphocytes (20-30%):

    • T cells: cell-mediated immunity.

    • B cells: humoral immunity (antibodies).

    • Natural killer cells: destroy abnormal cells.

• Differential Count:

  • Determines ratios of WBC types.

  • Leukocytosis: increased WBC count.

  • Leukopenia: decreased WBC count.

• WBC Production:

  • Lymphocytes: lymphoid stem cells.

  • Other WBCs: myeloid stem cells.

  • Monocytes mature in tissues.

Platelets

• Cell fragments from megakaryocytes.

• Important in clotting; stored in spleen.

• Circulate for 9-12 days.

• Abnormalities:

  • Thrombocytopenia: low platelet count.

  • Thrombocytosis: high platelet count.

• Functions:

  • Release clotting chemicals.

  • Temporary patch in vessel walls.

  • Tissue contraction after clotting.

Hemostasis

• Cessation of bleeding.

• Vascular Phase: vascular spasm.

• Platelet Phase: platelet adhesion and aggregation -> platelet plug.

• Coagulation Phase:

  • Cascade to form clot.

  • Common Pathway:

    • Factor X activation -> prothrombinase.

    • Prothrombin -> thrombin.

    • Fibrinogen -> fibrin.

    • Fibrin mesh traps RBCs.

• Clot retraction: platelets contract.

• Fibrinolysis: clot dissolves via enzymes.