Basophil Structure bilobate nucleus covered by densely staining basophilic granules Function mediates allergic reaction Derived from granulocyte precursors Pathologies basophilia seen with CML Other important features basophilic granules contain heparin (anticoagulant) histamine (vasodilator) vasoactive amines can synthesize leukotrienes Platelet (thrombocyte) Structure smallest formed element in the blood anucleate Function primary hemostasis and blood clotting prevents leakage of damaged vessels When activated by endothelial injury aggregates with other platelets interacts with fibrinogen to form hemostatic plug Derived from small fragments of membrane/cytoplasm from megakaryocytes Pathologies thrombocytopenia or platelet dysfunction results in petechiae, increased bleeding time Other important features contains dense granules (ADP, calcium) α-granules (vWF, fibrinogen) approximately 1/3 of platelet pool is stored in spleen asplenia results in thrombocytosis Lifespan = 8-10 daysimportant because aspirin permanently inactivates platelets and it takes this long to fully replenish functional platelets Erythrocyte Structure anucleatebiconcavegives large surface area to volume ratio Function gas exchange (O2 and CO2) due to large surface areaCO2 transportmembrane contains the chloride-bicarbonate antiporterimportant in the physiologicchloride shiftallows the RBC to transport CO2 from the periphery to the lungs for elimination CO2 transport membrane contains the chloride-bicarbonate antiporter important in the physiologicchloride shift allows the RBC to transport CO2 from the periphery to the lungs for elimination Derived from reticulocyte immature erythrocyte Pathologies anisocytosis = varying sizes poikilocytosis = varying shapes Other important features glucose functions as only source of energy RBCsvlack mitochondria so cannot use citric acid cycle β-oxidation of fatty acids ketone body synthesis survival time = 120 days Mast cell Structure cells in tissue with surface bound IgE Function mediates allergic reaction via degranulation when IgE on surface is crosslinked secretory granules contain histamine heparin eosinophil chemotactic factors also contains tryptase Derived from mast cells resemble basophils structurally and functionally and are derived from the same precursor Pathologies type I hypersensitivity reactions Other important features cromolyn sodium prevents mast cell degranulation Eosinophil Structure bilobate nucleus with large eosinophilic granules that do not cover the nucleus Function defends against invasive helminthic infections uses major basic protein phagocytoses antigen-antibody complexes contains reaction following mast cell degranulation produces anti-inflammatory histaminase and arylsulfatase Derived from granulocyte precursors Pathologies eosinophilia neoplasms (e.g., Hodgkins lymphoma) allergic processes asthma collagen vascular diseases invasive helminths Neutrophil Structure multilobed nucleus (3-5 lobes) with large spherical, azurophilic granules Function acute inflammatory response cell phagocytic Derived from granulocyte precursor Pathologies hypersegmented nuclei in B12 and/or folate deficiencies (> 5 lobes) Other important features granules contain hydrolytic enzymeslysozymemyeloperoxidaselactoferrin Monocyte Structure cells in peripheral blood larger than RBCs with kidney-shaped nucleus "frosted-glass" cytoplasm Function phagocytosis antigen presentation differentiate into macrophages when it reaches tissue Derived from monocytic precursor Pathologies monocytic leukemia Macrophage Function phagocytosis antigen presentation tissue healing Derived from circulating monocytes Pathologies chronic inflammation inflammatory may have dysregulated macrophages M. tuberculosis can live inside macrophages Other important features long life in tissues activated by γ-interferon Dendritic cells Function professional antigen-presenting cells (APCs) main inducers of primary antibody response Other important features called Langerhans cells in skin B lymphocyte Structure circular nucleus with small amount of surrounding pale cytoplasm Function antibody production B cells differentiate into plasma cells antigen presentation Derived from lymphocytic precursor in bone marrow matures in bone marrow also Pathologies B-cell lymphoma T lymphocyte Structure circular nucleus with small amount of surrounding pale cytoplasm Function mediates cellular immune responses T cells differentiate into cytotoxic T cells (MHC I, CD8) helper T cells (MHC II, CD4) also helps with antibody production suppressor T cells Derived from lymphocytic precursor in bone marrow matures in the thymus Pathologies helper T cells destroyed in HIV infection T-cell lymphoma Plasma cell Structure abundant RER off center nucleus with clock-face chromatin Function produce large amounts of antibody specific to a particular antigen Derived from B cells Pathologies multiple myeloma