Biology 1202B Lecture Notes - Caspase, Rna Interference, Histology
30 Apr 2012
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Diseases have been around much longer than humans. Physical barrier first line of defense: many of the body cavities are lined with mucus membranes, which contain environments that are hostile to pathogens. Example: acidic stomach kills most ingested bacteria and breaks down most viruses and if any survive, they are exposed to digestive enzymes and bile in the small intestine. Example: reproductive tract is acidic to prevent pathogen survival: consists of other physical barriers like skin, ear wax, eye lashes, etc, once something enters the body it is much more difficult to deal with and fight. Inflammation - creates an internal condition that inhibits or kills many pathogens: specialized cells engulf or kill pathogens or infected body cells. A break in the skin introduces bacteria, which reproduce at the wound site. Monocytes (a type of leukocyte) enter the damaged tissue from the bloodstream through the endothelial wall of the capillary.
