immune system innate Flashcards
innate defense
in place before exposure to a pathogen
includes physical barriers, cellular defense, chemical defense, inflammation
physical barriers
skin + mucous membranes
= form physical barriers and produce secretions
acid
skin, vaginal, stomach secretions are decreased pH (inhibits bacterial growth)
enzyme
lysozome in tears / saliva lyses bacteria; proteases digest microorganisms
mucus
sticky secretion in respiratory / digestive passages; traps microorganisms
defensins
atimicrobial peptides secreted by mucous membranes; inhibit bacterial and fungal growth
dermicidin
secretion in sweat that is toxic to bacteria
cellular defense
macrophages
neutrophils
natural killer cells
normal flora
macrophages
derived from monocytes that leave circulation; may be free (wander c.t.) or fixed (reside in organs)
neutrophils
most abundant phagocyte in blood and c.t
- intracellular killing = engulfs pathogen by phagocytosis; lysosomal enzymes digest pathogen
- extracellular killing = they degranulate
extracellular killing
neutrophils degranulate (releases granules contain toxins)
proteases (protein digesting enzymes)
defensins (pierce holes in cells)
free radicals (oxidizing chemicals)
NET
neutrophil extracellular trap
= neutrophil dies as a last resort when they release their genetic material and “NET” bacteria
natural killer cells
special granular lymphocytes that recognize and attack abnormal cells (immune surveillance)
release cytolytic chemicals that destroy cells that are virus infected or cancerous
normal flora
normally inhibit epithelial surfaces (normal flora) also provide some protection against pathogens
increase competition and stimulate defense mechanism
