NURSING 3PA2 Lecture 8: 4-immunity (formatted)
7 Mar 2018
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Document Summary
First line of defense is provided by the intrinsic barriers of the sin and mucus membranes. Can be mechanical, chemical, or microbiological in nature. Mechanical: expulsive forces (coughing, sneezing, defecation and urination), help to rid the body of pathogens before they can attach to and breach the mucus membranes. Ciliary beating helps to sweep pathogens from the upper and lower airways. Tight junctions in epithelium prevent pathogens from slipping between cells to enter underlying host tissue. Chemical: low ph (stomach, vaginal fluids and sebaceous fatty acids) prevent pathogenic bacterial colonization. Proteolytic enzymes (lysozymes, pepsin in gut) breakdown pathogenic components. Microbiological: commensal flora compete with the pathogens for resources (space and nutrients). Second line of defence is innate immune system; infers protection against a broad spectrum of pathogens through use of surface on phagocytic cells that recognize evolutionary conserved patterns unique to pathogens.
