Describe how the mammalian body protects itself against infections

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Pathogenic  microbes  are  found  on  the  skin,  respiratory  tract,  mouth,  vagina  and  the  intestinal tract;  the  skin;  has  a  keratinised  and  waterproof  cornified  outer  layer;  that  provides  a  mechanical barrier  to  microbes/prevents  entry  of  microbes;  sebaceous  gland;  produces  sebum;  which  has antiseptic  properties;  the  respiratory  tract;  produce  mucus  secretions  that  trap  dust;  cilia sweep/waft/propel  the  microbes  to  the  pharynx  for  swallowing  or  to  be  coughed  out;  reflex actions  of  coughing/sneezing/vomiting  help  remove  foreign  materials  from  the  respiratory tract/digestive  tract;  lysozymes/enzymes  in  saliva/nasal  secretions/tears;  digest  walls  of  bacteria destroying  them;  gastric  secretions  such  as  hydrochloric  acid  lowers  the  pH  in  the  stomach killing  micro-organisms;  clotting  of  blood;  prevents  entry  of  microbes  after  damage  of  blood vessels;  phagocytosis;  by  phagocytes  engulf  and  destroy  microbes  and  other  foreign  bodies; lymphocytes  are  stimulated  to  produce  antibodies;  by  proteins  present  in  microbes  protecting  the body;  antibodies  destroy/kill  micro-organisms  through  various  ways:  agglutinins;  bind  to pathogens  making  them  clump  together;  killing  them;  Lysins;  bind  to  pathogens  and  make  them burst  or  disintegrate;  opsonins;  bind  to  pathogens  making  them  easily  recognized  hence  be engulfed/destroyed  by  other  lymphocytes;  anti-toxins;  bind  and  neutralize  toxins  produced  by micro-organisms;  vagina  is  acidic;  hence  making  it  not  conducive  for  growth  and  reproduction  of micro-organisms;  Max:  20  mks 

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