Module 15

• Three lines of defense

  Ways in which the body protects itself from pathogens.
• Nonspecific


  The first two lines of defense.
• Immune response 


  Third line of defense
• Antibodies 


  In the third line of defense, special proteins called?
• Antigens 


  Are produced in response to foreign substances.
• Nonspecific host defense mechanisms

  Are general and serve to protect the body against many harmful substances.
• Skin and mucous membranes

  Physical barries
• Microbial antagonism 


  When indigenous microbiota prevent colonization of “new arrivals” as a result of competition for sites and nutrients and production of lethal substances.
• Transferrin 


  Levels of this glycoprotein increase in response to systemic bacterial infections; it binds to iron depriving pathogens of this vital nutrient.
• Fever 


  Stimulated by pyrogenic (fever-producing) substances
• Interferons 


  These are small antiviral proteins produced by virus-infected cells; they prevent viruses from multiplying.
• Alpha, beta and gamma

  Three different types of interferons
• Complement system 


  It is a group of about 30 different proteins found in normal blood plasma — “complementary” to the immune system.
• Complement Cascade 


  Complement components interact with each other in a stepwise manner known as the?
• Opsonization 


  It is a process by which phagocytosis is facilitated by the deposition of opsonins onto objects.
• Acute-phase proteins


  Plasma proteins that increase rapidly in response to infection, inflammation, or tissue injury.
• Cytokines 


  These are chemical mediators released from many different types of cells in the body; they enable cells to communicate with each other—within the immune system and between the immune system

  and other systems of the body.
• Chemokines


  These are chemoattractants; they recruit phagocytes to sites

  where they are needed.
• Inflammation 


  The body responds to any local injury, irritation, microbial invasion, or bacterial toxin by a complex series of events referred to as?
• Edematous (swollen) 


  Plasma that escapes from the capillaries into the site causes the area to become?
• Inflammatory exudate 


  The accumulation of fluid, cells, and cellular debris at the inflammation site is known as an?
• Purulent exudate or pus 


  If the exudate is thick and greenish-yellow, containing many live and dead leukocytes, it is known as a?
• Pyogenic microbes (pus-producing microbes)


  Staphylococci and streptococci result in additional pus formation.
• Phagocytes 


  Phagocytic white blood cells are called?
• Phagocytosis


  The process by which they surround and engulf (ingest) foreign material is called?
• Monocytes, lymphocytes, and granulocytes 


  Three major categories of leukocytes.
• Macrophages and neutrophils 


  The most important groups of phagocytes in the human body.
• Chemotaxis 


  Phagocytes are attracted to chemotactic agents to the site where they are needed.
• Attachment 


  A phagocyte attaches to an object.
• Ingestion 


  Pseudopodia surround the object, and it is taken into the cell.
• Digestion


  The object is broken down and dissolved by digestive enzymes and other mechanisms.
• Capsules 


  Initially serve to protect the organism from phagocytosis.
• Leukocidin 


  An exoenzyme which kills phagocytes.
• Leukopenia 


  An abnormally low number of circulating leukocytes.
• Actin 


  A structural protein associated with motility.