Blood
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Questions and Answers

Albumin serves as a transport vehicle for _____ and ___

Albumin serves as a transport vehicle for fatty acids and steroid hormones

What is the function of fibrinogen in the blood?

  • Maintaining fluid balance
  • Blood clotting (correct)
  • Regulating body temperature
  • Transporting hormones

    • Which of the following is NOT a function of blood?

  • Defense against pathogens
  • Producing insulin (correct)
  • Transporting metabolic wastes
  • Regulating pH

    • Which type of plasma protein is primarily responsible for maintaining fluid balance?

    <p>Albumin</p> Signup and view all the answers

    What does serum consist of?

    <p>Plasma without fibrinogen</p> Signup and view all the answers

    Which of the following is considered an electrolyte found in plasma?

    <p>Sodium</p> Signup and view all the answers

    Match to appropriate function

    <p>Erythrocytes = Aid in oxygen transportation Leukocytes (WBC) = Immune defense Platelets = Hemostasis Free bee = Free bee</p> Signup and view all the answers

    What is the primary growth factor involved in the proliferation and differentiation of erythroid precursors into rubriblasts?

    <p>Erythropoietin (EPO)</p> Signup and view all the answers

    Which nutrient is NOT required for the synthesis of heme in erythrocytes?

    <p>Vitamin K</p> Signup and view all the answers

    What feature of erythrocytes allows them to have a greater tolerance for osmotic swelling?

    <p>Lack of organelles</p> Signup and view all the answers

    What property of erythrocytes contributes to a larger surface area to volume ratio?

    <p>Discoid shape</p> Signup and view all the answers

    What is a common consequence of deficiencies in pyruvate kinase (PK) and phosphofructokinase (PFK) in erythrocytes?

    <p>Decreased glycolytic rates</p> Signup and view all the answers

    What is the main function of erythrocytes in mammals?

    <p>Carry oxygen and carbon dioxide</p> Signup and view all the answers

    What are the determinants of aged erythrocytes that lead to their removal by splenic macrophages?

    <p>Oxidative injury and surface membrane alterations</p> Signup and view all the answers

    What is the clinical significance of elevated direct bilirubin levels?

    <p>Suggests liver dysfunction or hemolysis</p> Signup and view all the answers

    Which of the following is a sign associated with erythrocytosis?

    <p>Increased risk of thrombotic events</p> Signup and view all the answers

    What is the primary difference between hematocrit and packed cell volume (PCV)?

    <p>Hematocrit is calculated; PCV is directly measured after centrifugation</p> Signup and view all the answers

    What change in plasma volume leads to relative polycythemia?

    <p>Decreased plasma volume</p> Signup and view all the answers

    Which of the following describes a common qualitative change in red blood cells?

    <p>Abnormal morphology or inclusions</p> Signup and view all the answers

    What distinguishes granulocytes from agranulocytes?

    <p>Presence of cytoplasmatic granules</p> Signup and view all the answers

    Which type of white blood cell is primarily responsible for initiating the inflammatory response?

    <p>Neutrophils</p> Signup and view all the answers

    How long do neutrophils typically survive in the bloodstream?

    <p>5-10 hours</p> Signup and view all the answers

    What characteristic of neutrophils allows them to migrate rapidly into tissues?

    <p>Shape of the nucleus</p> Signup and view all the answers

    Which type of leukocyte would show granules that do not stain with any dye?

    <p>Neutrophils</p> Signup and view all the answers

    What is the role of neutrophils in an inflammatory response?

    <p>To phagocytose infectious agents</p> Signup and view all the answers

    What is the main role of eosinophils in the immune response?

    <p>Fighting parasitic infections</p> Signup and view all the answers

    Which type of cell is considered part of the adaptive immune response?

    <p>B cells</p> Signup and view all the answers

    What distinguishes monocytes from lymphocytes?

    <p>Shape of the nucleus</p> Signup and view all the answers

    What is an important non-immune function macrophages/monocytes have?

    <p>Recycling dead cells</p> Signup and view all the answers

    Which of the following is true regarding basophils?

    <p>They are chemically similar to mast cells.</p> Signup and view all the answers

    Which statement about lymphocytes is accurate?

    <p>They include NK cells which are part of innate immunity.</p> Signup and view all the answers

    What is a significant characteristic of eosinophils in relation to allergic responses?

    <p>They release toxic substances from their granules.</p> Signup and view all the answers

    Which type of cell primarily carries out phagocytic functions in the immune system?

    <p>Monocytes</p> Signup and view all the answers

    What percentage of T lymphocytes typically survive the selection process?

    <p>1-2%</p> Signup and view all the answers

    What triggers naive T cells to stop migrating and start clonal replication?

    <p>Contact with antigen-presenting cells</p> Signup and view all the answers

    What is indicated by a left shift in neutrophils during a leukocyte evaluation?

    <p>An increase in immature neutrophils</p> Signup and view all the answers

    Which lymphocytes primarily circulate and make contact with multiple antigen-presenting cells in lymph nodes?

    <p>Naive T cells</p> Signup and view all the answers

    What is the primary role of B lymphocytes after their selection process?

    <p>To produce antibodies</p> Signup and view all the answers

    What is the physiological consequence of neutrophilia?

    <p>Increase in the number of neutrophils above normal limits</p> Signup and view all the answers

    What percentage of B lymphocytes typically survives the selection process?

    <p>Less than 20%</p> Signup and view all the answers

    What is the expected outcome of evaluating leukocytes?

    <p>Detecting hematopoietic neoplasia</p> Signup and view all the answers

    What is the primary function of platelets in hemostasis?

    <p>Form a clot by creating a platelet plug</p> Signup and view all the answers

    What regulates thrombopoiesis?

    <p>Thrombopoietin (TPO)</p> Signup and view all the answers

    Which phase in primary hemostasis involves vascular constriction?

    <p>Vascular phase</p> Signup and view all the answers

    What initiates the adhesion of platelets to the subendothelium during primary hemostasis?

    <p>Von Willebrand Factor (vWF)</p> Signup and view all the answers

    What is a direct effect of increased free thrombopoietin (TPO) on megakaryocytes?

    <p>Increased differentiation and production of platelets</p> Signup and view all the answers

    What is the lifespan of a platelet in circulation?

    <p>4-10 days</p> Signup and view all the answers

    What is the primary function of von Willebrand Factor (vWF) during platelet activation?

    <p>It binds to subendothelial collagen and aids platelet adhesion</p> Signup and view all the answers

    In which blood component does platelet activation primarily occur?

    <p>Platelets</p> Signup and view all the answers

    What structural change do platelets undergo during activation?

    <p>Form smooth discs to spheres with filopodia</p> Signup and view all the answers

    What is a characteristic sign of von Willebrand Disease in affected dogs?

    <p>Excessive bleeding from minor wounds</p> Signup and view all the answers

    What is the role of phosphatidylserine during platelet activation?

    <p>To move to the outer membrane surface and stimulate coagulation</p> Signup and view all the answers

    How does vWF affect factor VIII in the bloodstream?

    <p>It binds to and prolongs the half-life of factor VIII</p> Signup and view all the answers

    What is one of the main clinical challenges associated with von Willebrand Disease?

    <p>Affected dogs can have normal lifespans with appropriate management</p> Signup and view all the answers

    Match to their correct function

    <p>Glutathione = Protects RBC from oxidative damage Cytochrome B5 reductase = Reduces the non-functional methemoglobin 2,3 DPG = Promotes the release of oxygen to tissues Free bee = Free bee</p> Signup and view all the answers

    Aggregation to form a platelet plug is a reversible process

    <p>False</p> Signup and view all the answers

    Study Notes

    Functions of Blood

    • Transports dissolved gases (oxygen and carbon dioxide), nutrients, hormones, and metabolic wastes throughout the body.
    • Plays a crucial role in maintaining fluid balance within the circulatory system.
    • Regulates pH levels and ion composition of interstitial fluids, ensuring stability in cellular environments.
    • Engages in hemostasis, which restricts fluid loss at injury sites to prevent excessive bleeding.
    • Provides defense mechanisms against toxins and pathogens, contributing to immune function.
    • Helps stabilize body temperature by redistributing heat throughout the body.

    Plasma Proteins

    • The primary types of plasma proteins are albumin, globulins, and fibrinogen.
    • Albumin maintains osmotic pressure and transports various substances in the blood.
    • Globulins serve critical roles in immune response and transport of ions and hormones.
    • Fibrinogen, produced by the liver, is vital for the blood clotting process.

    Serum and Plasma

    • Serum is defined as plasma that has had fibrinogen removed, resulting in a liquid component without clotting factors.

    Solutes in Plasma

    • Electrolytes such as sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chloride (Cl), bicarbonate (HCO3), phosphate (PO4), and sulfate (SO4) are crucial for numerous physiological functions.
    • Non-protein nitrogen-containing compounds found in plasma include urea and creatinine, which are waste products.
    • Nutrients like glucose, lipids, and amino acids are transported by the plasma to cells for nourishment and metabolism.
    • Gases such as oxygen, carbon dioxide, and nitrogen are dissolved in plasma, facilitating respiration and metabolic processes.
    • Additionally, plasma contains hormones and enzymes that regulate various body functions.

    Hematopoiesis Overview

    • Hematopoiesis involves the proliferation and differentiation of hematopoietic stem cells into mature blood cells.
    • Key processes include erythropoiesis (red blood cells), leukopoiesis (white blood cells), and thrombopoiesis (platelets).

    Erythrocytes (Red Blood Cells)

    • Main functions:
      • Oxygen transport to tissues
      • Carbon dioxide transport from tissues
      • Buffers hydrogen ions (H+)
    • Structural characteristics:
      • Mammalian erythrocytes are anucleate and lack organelles.
      • Shape is circular, flattened, and bi-concave, enhancing surface area and minimizing diffusion distance.
      • Diameter ranges from 4 to 8 µm, allowing for flexibility and plasticity.
      • Possesses a cytoskeleton that supports shape changes and osmotic tolerance.

    Erythropoiesis

    • Stimulated by various growth factors:
      • Local factors in bone marrow: stem-cell factor (SCF), IL-3, GM-CSF, and thrombopoietin (TPO).
      • Peripheral tissue factor: erythropoietin (EPO) and triiodothyronine (T3).
    • EPO is crucial for the proliferation and differentiation of erythroid precursor cells into rubriblasts, the first identifiable erythroid cells.
    • The regulation of red blood cell (RBC) mass is dependent on cellular oxygen levels.

    Nutritional Requirements for Erythropoiesis

    • Essential nutrients include:
      • Iron: necessary for heme synthesis.
      • Vitamins B6, B9, B12: critical for various metabolic processes.
      • Copper and cobalt: play roles in erythropoiesis.
    • Due to the absence of mitochondria, erythrocytes utilize anaerobic metabolism and do not consume the oxygen being transported.

    Hemoglobin Structure and Function

    • Hemoglobin binds oxygen reversibly for efficient transport.
    • Composed of globin and heme; includes four polypeptide chains (two alpha and two beta chains).

    Biochemical Components of Erythrocytes

    • Important enzymes and compounds include:
      • Pyruvate kinase (PK): vital for glycolysis.
      • Phosphofructokinase (PFK): crucial in regulating glycolytic flux.
      • Phosphorus: integral for ATP generation.
    • Deficiencies in these components can result in decreased glycolytic rates, reduced ATP production, and premature death of red blood cells.

    Removal of Aged Erythrocytes

    • Erythrocytes circulate for several months before removal.
    • Aging triggers oxidative injury and ATP depletion, leading to surface membrane changes.
    • Senescent erythrocytes become denser and less deformable.
    • Key modifications include phosphatidylserine exposure and altered Band 3 proteins.
    • Membrane carbohydrate residues also change with age.
    • Splenic macrophages are responsible for the removal of aged erythrocytes.

    Bilirubin Metabolism

    • Indirect bilirubin is produced in the mononuclear phagocyte system (MPS) and binds to albumin in the bloodstream.
    • Direct bilirubin is formed through glucuronidation in the liver.

    Clinical Importance of RBC Evaluation

    • Quantitative changes observed in conditions like anemia, which is characterized by a decrease in RBCs.
    • Causes of anemia include blood loss, decreased production, and increased destruction.
    • Clinical signs of anemia: pale mucous membranes, weakness, lethargy, rapid pulse, and rapid breathing.
    • Erythrocytosis results from an increase in RBCs and can be categorized into absolute and relative forms.
      • Absolute polycythemia can be primary (EPO-independent) or secondary (EPO-dependent).
      • Signs include increased thirst/urination (PU/PD), lethargy, and brick red mucous membranes, with an elevated risk of thrombotic events.
      • Relative polycythemia occurs due to decreased plasma volume.

    Hematocrit vs. PCV

    • Both hematocrit and Packed Cell Volume (PCV) denote the percentage of total blood volume occupied by RBCs.
    • PCV is manually measured via microhematocrit after centrifugation.
    • Hematocrit is calculated based on RBC number and size.

    Qualitative Changes in RBCs

    • Abnormal morphology and the presence of inclusions can indicate qualitative changes in erythrocytes.

    Leukocytes (WBCs)

    • Heterogeneous population involved in the immune response.
    • Classified morphologically based on nucleus shape: mononuclear or polymorphonuclear.
    • Presence of cytoplasmic granules distinguishes granulocytes from agranulocytes.
    • Critical for both innate and adaptive immunity and hold significant diagnostic value.

    Granulocytes

    • Named according to staining properties showing affinity for different dyes.
    • Eosinophils: Stain with acidic dyes, involved in combating parasitic infections and allergies.
    • Neutrophils: Most abundant WBC, critical in the inflammatory response, with a segmented nucleus allowing quick tissue migration.
    • Basophils: Rare, involved in allergic responses and reacting to parasites; functionally similar to mast cells.

    Neutrophils

    • Primary responders in inflammation, capable of phagocytosing pathogens and enhancing inflammation through pro-inflammatory substances.
    • Short lifespan in bloodstream (5-10 hours) and limited survival in tissues (few days).
    • Serve as a primary indicator for inflammatory processes.

    Eosinophils

    • Predominantly located in the gastrointestinal mucosa.
    • Play a significant role in responses to parasitic infections and Type I hypersensitivity reactions.
    • Release toxic granules to destroy pathogens and assist in inflammation.

    Basophils

    • Present in very low numbers and associated with allergic reactions.
    • Less effective than eosinophils in response to parasites.

    Mononuclear/Agranulocytes

    • Characterized by a single large nucleus with fewer visible granules compared to granulocytes.
    • Monocytes: Larger than lymphocytes with variable nuclei shapes; differentiate into macrophages.
    • Lymphocytes: Generally possess round nuclei; key players in adaptive immunity.

    Monocytes/Macrophages

    • Monocytes differentiate into macrophages, which are vital for phagocytosis and immune coordination.
    • Activated macrophages inform other immune cells of infections and present antigens to lymphocytes.
    • Undertake non-immune tasks, such as recycling dead cells, without triggering immune responses.

    Lymphocytes

    • Diverse group essential for adaptive immunity.
    • B cells: Contribute to antibody production (10-40% of lymphocytes).
    • T cells: Attack foreign or cancerous cells (50-75% of lymphocytes).
    • NK cells: Kill tumor and infected cells, representing the innate immune response (5-10%).
    • Majority inhabit lymphoid organs rather than circulating in the blood (only 2-10%).

    Lymphocyte Formation

    • Precursors of T cells migrate to the thymus, while B cell precursors either move to the Bursa of Fabricius or remain in the bone marrow in mammals.
    • Only 1-2% of T lymphocytes survive the selection process, indicating a strong selection mechanism.
    • Less than 20% of B lymphocytes manage to survive; only a few selected lymphocytes enter circulation and reach peripheral lymphoid organs.

    Lymphocyte Circulation

    • Naive T cells circulate and are attracted to lymph nodes by chemotactic factors, making contact with numerous antigen-presenting cells daily.
    • Likelihood of a naive T cell being specific for a particular antigen ranges from 1 in 10,000 to 1 in 1,000,000.
    • If a naive T cell is not primed by an antigen, it recirculates to attempt activation in another lymph node.
    • Primed T cells, upon recognition of specific antigens, stop migrating, initiate cytokine release, and begin clonal replication for a few days.
    • Armed effector T cell clones exit the lymphoid organ and are directed to infection sites.

    Leukocyte Evaluation

    • Assessment of white blood cells (WBCs) focuses on count and morphology.
    • Key objectives include detection of inflammation, identifying infections, determining prognosis, and recognizing hematopoietic neoplasia.
    • Diagnosis of leukemia can also be made through leukocyte evaluation.

    Neutrophils and Shift Analysis

    • Neutrophilia refers to an increased number of neutrophils in the bloodstream, ranging from mild to severe conditions.
    • Neutropenia indicates a reduced number of neutrophils in the blood.
    • A "left shift" signifies an increase in immature neutrophils, regardless of total neutrophil count, often serving as an indicator of severe inflammatory responses.
    • Normally, only a small number of band forms are expected; a significant left shift with more immature neutrophils indicates a more intense inflammatory stimulus.

    Platelets

    • Small, anucleated, round to oval thin discs.
    • Lifespan of 4-10 days, crucial for primary hemostasis.

    Thrombopoiesis

    • Platelet precursor is the megakaryocyte, found in bone marrow and sometimes lungs.
    • Long proplatelet processes fragment into individual platelets.
    • Megakaryocytes are absent in nonmammalian species; these species use normal mitosis for precursors.
    • Regulated by thrombopoietin (TPO), produced by the liver, kidneys, and muscle.
    • Free TPO levels increase megakaryocyte production and differentiation; low platelet counts lead to increased free TPO.

    Hemostasis

    • Physiological process halting bleeding at injury sites while maintaining blood flow.
    • Involves primary hemostasis (platelet plug formation), secondary hemostasis (clot formation), and tertiary hemostasis (fibrinolysis and clot dissolution).

    Primary Hemostasis

    • Vascular phase involves vascular constriction.
    • Platelet phase includes:
      • Platelet adhesion to subendothelium, reliant on von Willebrand Factor (vWF).
      • Activation leading to shape changes, membrane alterations, and granule secretion.
      • Aggregation into an irreversible platelet plug, aided by ADP and Thromboxane A2.

    Von Willebrand Factor (vWF)

    • Synthesized by endothelial cells and platelets, circulates as multimeric strings.
    • Composed of over 100 subunits, molecular weights ranging from 500 to 20,000 kDa.
    • Functions as "platelet glue" by binding to subendothelial collagen, facilitating platelet interactions.
    • Binds and prolongs the half-life of factor VIII in blood.

    Platelet Activation

    • Triggered by adhesion (to collagen) and ligation (to thrombin and TXA2).
    • Shape change transforms smooth discs into spheres with extensive filopodia, increasing surface area.
    • Membrane flip moves negatively charged phosphatidylserine to the outer surface, enhancing procoagulant activity.
    • Granule secretion includes ADP, calcium, and factors V and VIII to facilitate further platelet activation.

    Secondary Hemostasis

    • Provides surfaces for fibrin formation and deposition necessary for clot stability.
    • Facilitates clot retraction through actomyosin contractions, aiding in wound closure and vessel patency.

    Role in the Immune System

    • Platelets contribute to immune responses apart from hemostatic functions.

    Clinical Correlation - Von Willebrand Disease

    • Most common inherited bleeding disorder in dogs, characterized by reduced, non-functional, or absent vWF.
    • Certain breeds, such as Doberman Pinschers and Poodles, are more susceptible.
    • Symptoms include skin bruising, prolonged bleeding from minor wounds, and excessive bleeding during surgery.
    • Diagnosis through vWF antigen assay and genetic testing.
    • No cure; management includes avoiding risky activities and pre-surgery plasma transfusion to prevent hemorrhage.

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