135986
Beschreibung
Mindmap von hannah_brewer, aktualisiert more than 1 year ago
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Erstellt von hannah_brewer
vor fast 11 Jahre
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Roles of skin, mucous membranes and
clotting of blood: preventing invasion of
micro-organisms
- The skin also is a major anatomical barrier to microorganisms. The surface layer of dead,
hardened cells is relatively dry, and skin secretions make the surface somewhat acidic.
When sweat evaporates, salt is left behind on the skin. All of these conditions (low
moisture, low pH, and high salinity) prevent most microorganisms from growing and
multiplying on the skin. The major medical challenge in treating burn patients is
preventing and treating infections that result because of the absence of skin that ordinarily
would prevent invasion of microorganisms.
- • The eye, mouth, and nasal openings are
protected by tears, saliva, or nasal secretions that
contain lysozyme, an enzyme that breaks down
bacterial cell walls. Blood, sweat, and some
tissue fluids contain lysozyme as well.
- • In addition to lysozyme, the blood has many elements that
defend the body from disease-causing organisms. The white blood
cells include several types of phagocytic cells that detect, track,
engulf, and kill invading bacteria and viruses, as well as infected
host cells and other debris. These phagocytic cells are part of the
nonspecific immune system.
- Blood plasma also includes clotting factors that initiate a clot at the
injury site, preventing pathogens from invading the body further.
Finally, the complement proteins in the blood participate in a
cascade of molecular events that result in inflammation, the release
of molecules that stimulate phagocytic cells, and the formation of a
complex of proteins that binds to the surface of bacterial or infected
host cells and lyses those cells.
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