after midterm

Cards (92)

  • stem cell niche
    • microenvironment
    • stem cells have to be in niche or they will differentiate
  • totipotent stem cells
    can form all cell types including plancenta and extra embryonic tissues
  • multipotent stem cells

    can form all cell types of the embryo
  • antiphagocystic factors
    factors that prevent phagocytosis
  • antiphagocytic factors and how they work
    • bacterial capsule
    • slippery, made from non-foreign material
    • antiphagocytic chemicals
    • prevent fusion of lysosomes and phagocytic cells
    • destroy white blood cells
  • leukocidins destroy white blood cells
  • listeria avoids the immune system by staying within a cell and moving between cells without leaving once
  • listeria enters new cells via the zipper mechanism
  • time determines if inflammation is chronic or acute
  • chronic inflammation is characterized by proliferative response
  • Chronic hallmarks
    • Infiltration by mononuclear cells (macrophages, lymphocytes, plasma cells)
    • proliferation of fibroblasts and vascular elements
    • increased scarring (fibrosis)
  • chronic inflammation = frustrated repair
    • irritant is persistent so result is not achieved
  • tuberculosis
    1. primary: initial infection
    2. secondary: dormancy period then reestablishment of infection
    3. disseminated: infection spreads throughout the body
  • tuberculosis diagnosed by skin test using ESAT6
  • ESAT6 stands for early secretory antigenic target
  • common antibiotics are ineffective against TB
  • TB vaccine is increasingly effective as we approach the equator
  • mycobacterium has a waxy lipid called mycolic acid
  • mycolic acid characteristics
    • waxy
    • slow growth
    • protection from lysis
    • high intracellular growth
    • resistance to gram staining, detergents, antimicrobial drugs, desiccation
  • M. tuberculosis produces cord factor
    • glycolipid
    • cells remain attached
    • inhibits migration of neutrophils
    • cytotoxic
    • prevents fusion of endosomes and lysosomes
    • stimulates granuloma formation w cytokines
  • granulomatous inflammation is a type of chronic inflammation
  • granulomatous inflammation is the accumulation of modified macrophages
  • TB pathogenesis
    1. inhalation (respiratory)
    2. adhesive pili attach to extracellular protein
    3. macrophages engulf bacteria, present MHC to helper T cell
    4. helper T cell attract more macrophages
  • intracellular receptors like toll-like receptors fight TB
  • development of TB in lung
    • recruitment of macrophages
    • rim of lymphocytes
    • caseous necrosis: cell death and appearance of grey/cream cheese
    • sometimes the tubercle ruptures and spreads
  • dormancy in TB: tubercle is calcified
  • ESAT 6 encourages the production of TNF-alpha and maintains the granuloma
  • M1 is pro-inflammatory, making a granuloma
  • Langan's giant cells have nuclei arranged in a horseshoe formation
  • mycolic acids are hard to process, probably causing the horseshoe shape
  • chronic inflammation leads to lymph nodules in abnormal places
  • viruses
    • have either DNA or RNA
    • neither grow nor respond to environment
    • no cytoplasmic membrane, cytosol, organelles
    • have an extracellular and intracellular state
    • cannot reproduce independently
    • use cell's metabolic pathways to increase numbers
  • virus in extracellular state
    • called virion
    • have a protein coat (capsid)
    • some have phospholipid bilayer
    • outermost layer provides protection and recognition sites
  • virus in intracellular state
    • capsid removed
    • exists as nucleic acid (DNA or RNA)
  • poliovirus is very small
  • viruses shapes
    • helical
    • polyhedral
    • complex
  • virus structure: capsid
    • protein shell surrounding the genome
    • capsomere is a subunit of the capsid
  • envelopes of virus come from the host
  • viral envelope proteins and glycoproteins play a role in host recognition
  • in rod shaped viruses, the
    • length is determined by the nucleic acid
    • width is determined by the protein package units