the skin and mucous membranes are the first line of defense: non- specific mechanical barriers to infection. composition- physical/mechanical defenses of the skin and mucous membranes. Innate immunity, nonspecific
skin= great physical barrier, oils (sacks of keratin on epidermis lubricate, metabolized by microbes as a food source) keratin is a tight water proof barrier that is like armor and is hard to digest , natural flora (staph, strep, candida albicans) occupies niches that make it difficult for pathogens to take hold. , pH (4-6) discourages the growth of many pathogens, sweat contains salt, urea and lysozyme, .
mucous membranes= respiratory system (nasal, throat, trachea, bronchii, alveoli, mucus, hair, sneeze, cilia) GI tract (saliva, protects from tooth decay, mucous membranes, pH extremes, peristalsis) UG tract (urigenital tract, urine system, acidic pH (4.3-4.9) Mucus membranes line the GI, respiratory and genitourinary tracts. The epithelial lay secretes a fluid called mucus, a slightly viscous glycoprotein produced by goblet cells of a mucous membrane. It prevents the tracts from drying out and serves as a mechanical barrier to microbes.