immunity system and innate Flashcards
what four components protect us against microorganisms?
Physical barriers
Cellular components
complement system and mediators of inflammation
Cytokines
what are the physical barriers?
epithelial surfaces i.e skin GI tract and respiratory tract.
Secrete anti microbial substances: defensins
what are the cellular components?
Neutrophils (large multi lobed nucleus, many organelles
Macrophages (large rounded nucleus, many organelles)
Dendritic cells (small nucleus to cytoplasm ratio
what is the function of Neutrophils?
Phagocytosis
Reactive oxygen and nitrogen species,
Antimicrobial peptides
Function of Macrophages
phagocytes, inflammatory mediators,
Antigen presentation
Reactive oxygen and nitrogen species
Cytokines
Function of Dendritic cells
antigen presentation
reactive oxygen species,
Cytokines
cellular function
recognise structures on microbes not present on mammalian cells using pattern recognition receptors
what are toll like receptors?
found on most cells of innate immune system,
10 mammalian forms
they respond to variety microbial markers and they result in up regulation of inflammatory gene expression
what is Lipopolysaccharide LPS?
also known as endotoxin
product of gram negative bacterial cell wall
stimulates innate immune system
Pathogenic: induces local and systemic inflammation.
potent activator of macrophages inducing cytokine release and reactive oxygen.
process of phagocytes
Bacterium becomes attached to membrane evaginations called pseudopodia
Bacterium is ingested forming phagosome
Phagosome fuses with lysosome
Lysosomal enzymes digest captured material
Digestion products are released from cells
What is the complement system?
Cascade of plasma proteins
Activated by microbes resulting in their destruction,
Zymogens; gain enzymatic activity by cleavage.
3 pathways; classical, alternative and lectin
