questions 2

Blood Cell Types

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Topic updated on 06/09/17 8:58pm

Basophil
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 days
      • important because aspirin permanently inactivates platelets and it takes this long to fully replenish functional platelets
Erythrocyte 
  • Structure
    • anucleate
    • biconcave
      • gives large surface area to volume ratio
  • Function
    • gas exchange (O2 and CO2)
      • due to large surface area
    • CO2 transport
      • membrane contains the chloride-bicarbonate antiporter
      • important in the physiologic chloride 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
    • RBCs lack mitochondria so cannot use
      • citric acid cycle
      • β-oxidation of fatty acids
      • ketone body synthesis
    • survival time = 120 days
Mast cell
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
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
 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 enzymes
      • lysozyme
      • myeloperoxidase
      • lactoferrin
Monocyte
 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
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
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
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
 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


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