plate 49 establishment of disease. skin epithelium – outer part of skin epi: “on” theli:...
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Skin
• Epithelium – outer part of skin
• Epi: “on”• Theli: “tissue”• Densely packed
cells protect body from invading pathogens
Skin
• Connective tissue – provides cohesion and support to internal structure of the body
• Fibers provide flexibility and form
Phagocytes
• After a foreign substance has ruptured the skin, phagocyte cells migrate to the site
• Phagein: “to eat”• Cyte: “cell”• Phagocytes – group of immune
cells specialized in “eating” potential pathogens
• Pus from an infection is primarily dead phagocytes
Phagocytosis
• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__phagocytosis.html
Bacterial Enzymes
• Bacteria use enzymes to help establish themselves in the body:– Coagulase– Hyaluronidase– Streptokinase– Hemolysis
Coagulase
• Coagulase is secreted by some bacteria (ex: Staphylococcus)
• Causes proteins in blood to clot
• Commonly found in Gram positive bacteria
• Blood clot surrounds bacteria and protects against phagocytes
Hyaluronidase
• Hyaluronic acid (hyaluronan) is found in epithelial and connective tissues and acts as a “goo” in tissue repair
• Bacteria (ex: Clostridium) secrete hyaluronidase enzyme to breakdown hyaluronic acid
• It allows bacteria to infiltrate skin barrier• Fun fact: sperm secrete hyaluronidase when they come into
contact with an egg
Streptokinase
• Some bacteria (ex: Streptococcus) secrete streptokinase enzyme to dissolve blood clots
• Allows bacteria to spread past the location of initial infection
• Also used in heart attack victims to dissolve arterial blood clots in the heart