Microbiology and Immunology 2500A/B Lecture Notes - Lecture 2: Pepsin, Peristalsis, Nod2
12 Sep 2016
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The first line of defense against a pathogen. Effective at stopping majority of pathogens at early stage. Inherited from parents (born with innate immune defenses; well conserved) Responds immediately to a pathogen (pathogen usually eliminated before symptoms arise. No memory (same immune response to identical pathogen with each exposure [i. e. non- adaptive]) If innate immunity is unsuccessful, certain innate cells initiate adaptive immunity to help eliminate the pathogen. Modes of pathogen entry into body: skin (wound, gastrointestinal tract (ingestion, respiratory tract (breathing, reproductive path. 2 and 3 are the entries for most pathogens. Physical barrier that prevents pathogen entry: epithelial cells. Efflux of nutrients, essential ions, etc. out of the microbe. Influx of water from extracellular environment into microbe. Cilia in lungs, coughing, sneezing, vomiting, diarrhea, tears, blinking, earwax, peristalsis, urine, saliva, mucus. Enzymes: lysozyme (saliva, sweat, tears), pepsin (gut) Low ph (stomach) most microbes don"t survive in acidic environment.
