Barrier functions of the body

Barrier functions of the body play an important role in the body's defence against exogenous agents, ie in particular viruses, parasites and bacteria. The basic preconditions for the body's defence include the following:


 * intact skin,
 * mucosa (respiratory, GIT, urinary); phlegm; cough reflexes, sneezing, vomiting, diarrhoea,
 * acidic pH in the stomach,
 * a series of bactericidal substances,
 * partial pressure oxygen in tissues,
 * body temperature,
 * age ("maturation" immune system),
 * intact physiological urine outflow,
 * lysozyme,
 * the action of other systems:  endocrine,  hemocoagulation.

Natural non-immune mechanisms are divided into:
 * 1) mechanical: cilia movement, longitudinal airflow in the airways or fluid in the urinary tract;
 * 2) chemical: fatty acids on the skin, enzymes (lysozyme, pepsin, antibacterial peptides = defensins ), acidic pH in stomach and urine;
 * 3) microbial: normal non-pathogenic microflora competing with pathogens for nutrients and receptor sites producing antibacterial agents.

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