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Types of immunity
- Innate resistance: Natural barriers and the inflammatory response
- Adaptive (acquired) immunity
Lines of defense
- First line: Natural barriers: physical, mechanical and biochemical
- Second line: Inflammation
- Third line: Adaptive (acquired) immunity
First line of defense: Physical and mechanical barriers
- Skin and low temp/pH of skin
- Linings of the gastrointestinal, genitourinary, and respiratory tracts
•Highly interconnected junctions
•Sloughing off of cells
•Coughing and sneezing
•"Washing"
•Vomiting
•Urinating
•Mucus and cilia
First line of defense: Biochemical barriers
,- Synthesize and secrete substances to trap or destroy microorganisms (Antibacterial peptides in mucus,
perspiration (sweat), saliva, tears, and earwax)
- Antimicrobial peptides (Cathelicidins, defensins (α defensins in neutrophil granules and β defensins),
and collectins (lungs))
- Normal microbiome (Inhibits colonization by pathogens; releases chemicals that prevent infection)
•Vaginal: Lactobacillus
•Intestinal: Ammonia, phenols, and indoles
Second line of defense: Inflammation
- Cellular and chemical components
- Nonspecific: Takes place in approximately the same way, regardless of the type of stimulus or whether
exposure to the same stimulus has occurred in the past.
- Rapidly initiated
- No memory cells
Second line of defense: Inflammation - Causes
Infection, mechanical damage, ischemia, nutrient deprivation, temperature extremes, and radiation
Second line of defense: Inflammation - Cardinal signs
Redness, heat, swelling, pain, loss of function
Second line of defense: Inflammation - Vascular response
Blood vessel dilation, increased vascular permeability and leakage, white blood cell (WBC) adherence to
the inner walls of the vessels, and migration through the vessels (diapedesis)
, Second line of defense: Inflammation - Once in the tissues, the cells and chemicals associated with the
inflammatory response, do what?
- prevent and limit infection and further damage.
- limit and control the inflammatory process.
- interact with components of the adaptive immune system.
- prepare the area of injury for healing
Protein systems that provide a biochemical barrier against invading pathogens are the:
- complement system.
- clotting system.
- kinin system.
Plasma protein systems all contain:
- inactive enzymes (proenzymes).
- Sequentially activated-cascade
a. First proenzyme is converted to an active enzyme.
b. The activation of the first component of a system results in sequential activation of other components
Complement system
- Can destroy pathogens directly
- Activates or collaborates with every other component of the inflammatory response
Complement system: Pathways