immunity—non-specific/innate overview of immune response first line of defense—barriers second...
Post on 19-Jan-2018
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Immunity—non-specific/innate
• Overview of immune response• First line of defense—barriers• Second line of defense
– Phagocytosis– Inflammation– Complement– Fever
• Relationship to specific immune response or Third line of defense
First Line of Defense
• Physical barrier on all surfaces of body exposed to external world
• What are they?– Skin– Mucous membranes—nasal, respiratory– Lining of mouth– Lining of gut– Lining of vagina/urethra– Surface of eye
How do barrier membranes keep bacteria out?
• Chemical barrier—antibacterial secretions• Cellular barrier—cells tightly packed and
sloughed off (10B skin cells/day=250 g./year)• Physical barrier—thick, mucousy and sticky
secretions trap bacteria• Resident microbes—have commensal or
mutualistic bacteria and fungi that are normally present and out-compete potential pathogens
• First line of Defense—physical barrier
• Second Line of Defense– Phagocytosis– Inflammation– Complement– Fever– All work tightly with specific immunity
• Phagocytes move through blood and lymph and into connective tissues (part of inflammation response as cells and fluid move out of capillaries into surround aleolar tissues--diapedesis)
Phagocytosis
Complement
• Group of free proteins in blood that respond to antigen/antibody complex (huh?—coming soon)
• Cascade of reactions eventually makes MAC’s—membrane attack complex—that bores hole in bacterial membrane
• Gram-negative bacteria more susceptible
Inflammation• Response to tissue damage from any
source (burn, cut, pathogen, other??)• Blood vessels dilate allowing for better
delivery of nutrients, O2, antibodies, complement, immune cells
• Phagocytes (monocytes and neutrophils) migrate out of capillaries--diapedesis
Fever
Pluses• Inhibit microbial growth• Enhance immune cell
performance• Speed tissue repair
Minuses• Malaise• Body aches• chills
Trigger not completely understoodMuscular contraction and constriction of skin blood vessels cause core temperature to rise
“Breaking” fever or “crisis of fever”: • body begins to cool by sweating,• “color returns” as blood vessels in skin open• Indicates infection is overcome
Links from innate (2nd line) to specific/adaptive (3rd line) Immunity
• Phagocytosis continues to be common way to kill pathogenic cells in both specific and non-specific response
• Inflammation works to allow both specific and non-specific immune response to accelerate
• Fever also allows for better performance in both specific and non-specific function
• Specific immune response and “antigen presentation” further stimulates non-specific actions like phagocytosis, complement.
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