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23 Cards in this Set
- Front
- Back
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What is innate immunity? |
the first two lines of defense -present at birth prior to contact with infectious agents or their products
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What is adaptive immunity? |
-third line of defense -responds against unique species or strains of pathogens and alters the body's defenses such that they act more effectively upon subsequent infection with the specific strain |
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Describe the body's first line of defense (kind of how it works) |
-structures, chemicals, and processes that work to prevent pathogens entering the body
-skin and mucous membranes of the respiratory, digestive urinary and reproductive systems
-normal microbiota has two roles in innate immunity = 1. microbial antagonism 2. activities of normal microbiota make it hard for pathogens to compete |
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Define microbial antagonism? |
-where normal microbiota play a role in protecting the body by competing w/ potential pathogens in a variety of ways |
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Briefly describe the body's second line of defense? |
-no barriers -composed of cells (phagocytic) -antimicrobial chemicals (peptides, complement, interferons) -processes (inflammation, fever)
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Describe the components of blood that are part of the second line of defense? |
-plasma -three types of formed elements - erythrocytes, platelets, leukocytes |
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Describe erythrocytes |
-most numerous -carry oxygen and carbon dioxide in the blood |
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Describe platelets |
-pieces of large cells that have split into small portions of cytoplasm surrounded by cytoplasmic membranes -involved in blood clotting |
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Describe leukocytes |
-the formed elements that are directly involved in defending the body against invaders -commonly called white blood cells |
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What is phagocytosis? |
-killing of pathogen once ingested 1. chemotaxis (mvmnt of cell toward or away from chemical stimulus) of phagocyte to microbes 2. adherance 3. ingestion of microbes by phagocytes 4. fusion of a series of vesicles including lysosomes 5. killing of microbes by enzymes and other chemicals 6. elimination (exocytosis) {reverse of ingestion} |
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What is nonphagocytic killing? |
-can accomplish killing pathogen without phagocytosis
-uses eosinophils; natural killer lymphocytes, neutrophils |
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Describe eosinophils? |
-can phagocytize but don't usually -kill by secreting antimicrobial chemicals |
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Describe natural killer lymphocytes? |
-(NK cells) -work by secreting toxins onto the surfaces of virally infected cells and neoplasms (tumors) |
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Describe neutrophils? |
-dont always devour pathogens -can destroy pathogen in two ways: 1. enzymes in a neutrophil's cytoplasmic membrane add electrons to oxygen 2. synthesize Neutrophil extracellular traps (NETs) via cellular suicide involving disintegration of their nuclei. ----- as nuclear envelope breaks down, DNA and histones are released into the cytosol --- the NETS released from the dying cell traps and kills gram neg and pos bacteria |
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What are the 3 nonspecific chemical defenses against pathogens? |
-toll like receptors (TLRs) -Interferons -Complement |
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Describe toll-like receptors? |
-integral membrane proteins produced by phagocytic cells -bind pathogen-associated molecular patterns (PAMPS) -initiate defensive responses |
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Describe interferons |
-protein molecules released by host cells to nonspecifically inhibit the spread of viral infections -cause many symptoms associated with viral infections |
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Describe compliment system? |
-set of serum proteins designated numerically according to their order of discovery -complement activation results in lysis of the foreign cells -membrane attack complex -classical pathways, alternative pathways, lectin pathways |
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Describe the different pathways in the complement system? (3) |
-classical - antibodies activate compliment
-alternative pathway - pathogens activate compliment
-lectin pathway - microbial polysaccharides bind to activating molecules |
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Describe Inflammation |
-nonspecific response to tissue damage from various causes -causes redness, heat, swelling, and pain -dilation and increased permeability of blood vessels |
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Describe the dilation and increased permeability of blood vessels? |
-initial response to injury or invasion of pathogens -release of inflammatory mediators |
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Describe Fever |
-body temp over 37C -various types of pyrogens -outcome of fever is to enhance immunity
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Define what a pyrogen is? |
-trigger the body to react and reset at a higher temp -include bacterial toxins, cytoplasmic contents of bacteria that are released upon lysis, antibody-antigen complexes formed in adaptive immune responses |
