1st Line of Defense
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- Consists of physical and chemical barriers that prevent pathogens from entering the body
- The primary line of defense against infection usually occurs on the body’s surface
- Examples of physical barriers :
~Intact skin: Prevents pathogen entry as its tightly packed with epidermal cells. It is rarely ever penetrated by bacteria but is usually punctured resulting from a cut or a micro-organism, then foreign matter may enter
~Cilia: located in the throat. Small hair-like structures that move back and forth, pushing any foreign matter down towards the stomach where it is exposed to gastric acids that the pathogen usually cannot withstand.
~Ear wax: A natural antibiotic that is a stick substance found in the ear that is protective of outer ear infections and is able to trap pathogens till they are removed.
- Examples of chemical barriers:
~Mucous secretion: Mucous contains various anti-microbial compounds (i.e. lysozyme and secretory antibodies) that assist in trapping foreign matter in respiratory and digestive tracts.
~Normal flora of the skin: non-pathogenic micro-organisms that metabolize substances secreted onto the skin that prevent pathogen growth as will have to compete for space and nutrients
- sweat contains high concentrations of salt and lysozomes causing the skin to be unappealing to most pathogens
~Tears: Contains large amounts of lysozymes that break down the cell walls of foreign matter and flush it out of our eyes
~Gastric acid: Destroys bacteria and most toxins in the stomach due to the pathogens not being able to handle the pH levels