Mammals - non-Specific Defences

Mammals have 2 lines of defence against pathogens.primary non-specific rapid, always presentspecific - slower, specific to each pathogenThe skin is the largest organ in the body. It provides a physical barrier against the entry of pathogens. The skin is covered in non-pathogenic microorganisms that compete for space on the surface of the body.The healthy skin flora inhibit the growth of pathogen microorganisms.The mucosa is the moist, innermost lining of internal organs and body cavities that connect to the outside, such as the digestive, respiratory, and urogenital tracts.These mucous membranes act as a physical barrier by secreting mucus to trap pathogens and dirt.Mucus is a sticky gel that is 95% water and contains glycoproteins called mucins, and salts, lysozymes and phagocytes.Other mechanisms of defence are lysozymes in tears and hydrochloric acid in the stomach which kills ingested pathogens.Expulsive reflexes such as coughs and sneezes expel pathogens from the respiratory system. . Diarrhoea and vomiting expel the contents of the gut.