Histology of blood cells

Cards (47)

  • Anemia: Decrease of concentration of the erythrocytes in the blood
  • Erythrocytosis or polycythemia: Increase number of red blood cells in the blood, generally related to physiological situations
  • Macrocytes: Greater than 9 μm
  • Microcytes: Less than 6 μm
  • Anisocytosis: Cells vary greatly in size
  • Combination of Hemoglobin with respiratory gases:
    • Oxyhemoglobin: Combination with oxygen
    • Carbaminohemoglobin: Combination with carbon dioxide
    • Carboxyhemoglobin: Combination with carbon monoxide, irreversible
  • Erythrocyte cytoplasm lacks all organelles but is densely filled with hemoglobin
  • Shape of erythrocyte maintained by membrane proteins:
    • Integral membrane proteins: glycophorins, band 3
    • Peripheral membrane proteins: cytoskeletal proteins including spectrin, tetramers, actin, band 4.1 protein
  • Life span of erythrocytes is about 120 days
  • Sickle cell disease caused by a single-point mutation in the gene encoding the β-globin chain of hemoglobin A:
    • Sickle erythrocytes are inflexible
    • Shortened life span leading to profound anemia
    • Much more viscous than normal cells
  • Leukocytes (White Blood Cells)
  • Granulocytes:
    • Neutrophils
    • Eosinophils
    • Basophils
  • Agranulocytes:
    • Lymphocytes
    • Monocytes
  • Neutrophils:
    • Constitute 60-70% of circulating leukocytes
    • Nucleus with 2-5 lobes, hypersegmented if more than 5
    • Specific granules (secondary granules) stained salmon pink, azurophilic granules (primary granules) stained deep reddish-purple
    • Short-lived cells with a half-life of 6-7 hours and a life span of 1-4 days in connective tissue
  • Eosinophils:
    • About the same size as neutrophils, typically bilobed nuclei
    • Specific granules stained by eosin, contain histaminase, collagenase, cathepsins
    • Associated with allergic reactions, parasitic infections, and chronic inflammation
  • Basophils:
    • Less than 1% of blood leukocytes
    • Numerous large granules in cytoplasm stain with basic dyes
    • Specific granules contain heparin, histamine, heparan sulfate, leukotrienes, IL-4, IL-13
    • Azurophilic granules are lysosomes containing lysosomal acid hydrolases
  • Lymphocytes:
    • Second most numerous white cells in the blood
    • Nuclei ovoid or kidney-shaped, dense chromatin
    • Three functionally distinct types: T lymphocytes, B lymphocytes, NK cells
  • Monocytes:
    • Precursors of cells of the mononuclear phagocytic system
    • Transform into macrophages, function as antigen-presenting cells
    • Oval, horseshoe-shaped, or kidney-shaped nuclei, basophilic cytoplasm with fine azurophilic granules
    • Half-life in blood is 12-100 hours, no strong evidence of recirculation after entering connective tissues
  • Platelets (Thrombocytes)
  • Non-nucleated, disc-like cell fragments 2-4 μm in diameter
    • Originate from fragmentation of giant polyploid megakaryocytes in bone marrow
    • Promote blood clotting and help repair minor tears or leaks in small blood vessels
    • Life span about 10 days
  • Structurally divided into four zones:
    • Peripheral zone: cell membrane with glycocalyx
    • Structural zone: microtubules, actin filaments, myosin
    • Organelle zone: mitochondria, peroxisomes, glycogen particles, granules
    • Membrane zone: open canalicular system, dense tubular system
  • Platelet Function:
    • Primary aggregation: platelet plug formation
    • Secondary aggregation: release of adhesive glycoprotein and ADP for further aggregation
    • Blood Coagulation: factors promote fibrin formation for clotting
    • Clot reaction: clot contracts in blood vessel lumen
    • Clot Removal: plasmin enzyme removes clot, new tissue formation restores wall
  • Blood cells include erythrocytes (red blood cells), leukocytes (white blood cells), and platelets (thrombocytes)
  • Staining methods for blood cells include Romanovsky mixed dyes, Giemsa’s, Leishman’s, and Wright’s dyes
  • Erythrocytes lack organelles but are filled with hemoglobin, maintaining their shape with membrane proteins
  • Anemia is a decrease in erythrocyte concentration, while erythrocytosis is an increase, often related to physiological conditions
  • Erythrocytes have different sizes: macrocytes (>9 µm), microcytes (<6 µm), and anisocytosis refers to cells varying greatly in size
  • Erythrocytes form reversible combinations with respiratory gases like oxyhemoglobin and carbaminohemoglobin
  • Sickle cell disease results from a mutation in the gene encoding the β-globin chain of hemoglobin A, causing inflexible, viscous erythrocytes
  • Neutrophils are the most common type of white blood cell, produced in the bone marrow and released into the bloodstream to fight infection
  • Neutrophils contain granules with antimicrobial peptides and proteins, enzymes, and chemicals like histamine to kill bacteria
  • Neutrophils have a short lifespan of 6-7 hours in the blood and 1-4 days in connective tissue
  • Eosinophils are white blood cells associated with allergic reactions, parasitic infections, and chronic inflammation
  • Eosinophils contain specific granules with histaminase, collagenase, and azurophilic granules with hydrolytic enzymes
  • Eosinophils play a major role in host defense against helminthic parasites and are found in large numbers in allergic conditions
  • Basophils are white blood cells with large granules that stain with basic dyes, containing substances like histamine and leukotrienes
  • Basophils are less than 1% of blood leukocytes and have granules similar to mast cells
  • Lymphocytes are the second most numerous white cells in the blood, increasing in response to viral infections and playing a crucial role in the immune response
  • Platelets are non-nucleated, disc-like cell fragments 2-4 µm in diameter, originating from giant polyploid megakaryocytes in the bone marrow
  • Platelets promote blood clotting and help repair minor tears or leaks in small blood vessels, preventing blood loss from the microvasculature